Synthetic for flat tappet SBC

[Dallas69]

For the engine in question here a 1965 283 Chevy I would not use a Ow oil.
I said nothing about a 5-40 either.
He asked for opinions so this is mine.
He can run what he wants and report back
May e he will run 0-20 and let us know how that works.
I'm sure his engine will let him know.

 

[kschachn]

Originally Posted By: Dallas69
For the engine in question here a 1965 283 Chevy I would not use a Ow oil.
I said nothing about a 5-40 either.
He asked for opinions so this is mine.
He can run what he wants and report back
May e he will run 0-20 and let us know how that works.
I'm sure his engine will let him know.


It wasn't about 5W-40 or 0W-40 just about the "W" part. It doesn't matter which overall grade, the concept is the same is it not? I'm not suggesting he uses 0W-20 for that matter, and as far as I can see in this thread no one else has either. Most of the posts are about a 40-weight so a question about 0W-40 vs. 5W-40 seems appropriate.

You stated that he shouldn't use a "0W" because it might be too thin when cold. I still haven't seen how that can be true.

 

[BrocLuno]

Well stretching credulity some, let's say the engine wants a thick film when cold and before pumped oil is really circulating. The cam in this motor will have to live on residual cold oil film for a couple of minutes on start-up until the crank can sling enough new oil to replace. In that case 0W might be a bit thin, but so might 5W ...

283 Chevies from this era started and ran in Wisconsin all through teh 60's and 70's on 10W-30 w/o incident. Lots of them lived on SAE 30 HD as that's is what their buyers had grown up on. Long before synthetics were common, and with ridiculous amounts of VII's in cheap oil. They died not die. This one is still running, apparently well

Wisconsin and Sweden should have about the same starting conditions. Some folks from there should go ask Dad what he put in their old Chevy back then? 10W-30 up to about 100,000 miles and then 10W-40 till it dies was not uncommon. And we are discussing the finer points of 0W vs 5W ...

 

[Dallas69]

I said 10-30 or 10-40 but the thread kind of got hijacked.

 

[kschachn]

I'll agree with that part. Quite a stretch to claim that somehow a 0W-30 would be too thin on cold startup but a 10W-30 would be fine.


Originally Posted By: BrocLuno
Well stretching credulity some, let's say the engine wants a thick film when cold and before pumped oil is really circulating. The cam in this motor will have to live on residual cold oil film for a couple of minutes on start-up until the crank can sling enough new oil to replace. In that case 0W might be a bit thin, but so might 5W ...

283 Chevies from this era started and ran in Wisconsin all through teh 60's and 70's on 10W-30 w/o incident. Lots of them lived on SAE 30 HD as that's is what their buyers had grown up on. Long before synthetics were common, and with ridiculous amounts of VII's in cheap oil. They died not die. This one is still running, apparently well

Wisconsin and Sweden should have about the same starting conditions. Some folks from there should go ask Dad what he put in their old Chevy back then? 10W-30 up to about 100,000 miles and then 10W-40 till it dies was not uncommon. And we are discussing the finer points of 0W vs 5W ...

 

[Trav]

Originally Posted By: BrocLuno
Well stretching credulity some, let's say the engine wants a thick film when cold and before pumped oil is really circulating. The cam in this motor will have to live on residual cold oil film for a couple of minutes on start-up until the crank can sling enough new oil to replace. In that case 0W might be a bit thin, but so might 5W ...


Isn't this where the sacrificial zinc layer comes into play with flat tappets?

 

[BrocLuno]

That layer should never be relied on. It's your last line of defense before failure. You do not want to live there.

Viscosity and cold film strength are what's needed for these old flat tappet motors to run long happy lives. They get enough oil when running and warmed up. It's start-up that is tough ...

 

[Trav]

I understand that and agree to a point but There is just too much evidence that higher zinc levels are necessary not just as a last line of defense.

https://www.hemmings.com/blog/2012/10/18/tech-101-zinc-in-oil-and-its-effects-on-older-engines/

 

[jongies3]

I'd look into Edge 5W-50, it's specifically designed for older flat tappet engines and classic cars. Rotella T6 5W-40 is another viable option as well because it has high zinc too.

 

[aquariuscsm]

Mobil 1 15W50.

 

[Carlostrece]

Originally Posted By: Nickdfresh
Can you get (Euro) Valvoline MaxLife High Mileage 5W-40? It would be perfect for this application IMHO...


Agreed. Based on what I've read about Valvoline 5W40 it should be good for his older car.

Almost any American or European brand of 5W40 would be good, IMO. Especially ones rated for both diesel and gas engines, or for Euro gas engines. Shell Rotella T6 and Penzoil Euro 5w40 come to mind as two of my favorites, along with Valvoline 5w40.

I'm currently using Penzoil Euro 5W40 in my older USA vehicle. I don't claim to be an expert, but I know a few things. It's working well for me. I'm also considering Shell Rotella T6 5w40 and Valvoline 5W40 for my two older cars.

===

I avoid 0W40 because I tried Mobil One 0W40 for 10,000 miles. It wasn't good in my older engines because it didn't hold it's viscosity. After about 2500 to 3000 miles the oil pressure dropped slightly, but noticeably. The oil seemed thinner. I change oil every 5000 miles, which is appropriate for my driving style of half city, half highway.

I would avoid any oils starting with 10W, 15W, or 20W oils because in your cold Swedish climate they'd be to thick at cold start, when you have to move the car in Winter, IMO.

===

Just my personal opinion, but I would avoid Castrol and Royal Purple products. In the past, I've read poor reports from independent lab tests done by Consumer Reports and others.

===

Others may have other opinions.

===

P.S. - I talked with an oil expert in my hometown who has experience working for Mobil and Chevron truck stops. He told me for my older car to avoid any OW oils (0W30 or 0W40) because they might not hold their viscosity well enough. He recommended 5w40 in any brand. I didn't listen and tried 0W40 anyway. Sure enough, 0W40 didn't hold it's viscosity well enough past 3000 miles. So I should have learned that by advice, but since I didn't listen I had to learned by experience.

 

[Carlostrece]

In prior post, when I recommended Valvoline 5W40, I meant SynPower or Maxlife. Whichever is available.

After more thought, a 5W50 would also be good, especially if it's rated for gas and diesel, or Euro rated, or high mileage rated. I don't know any brands of 5W50 to recommend, but I assume it exists.

IMO

 

[Berget]

I think I will ditch the M1 0W-40 for something else…

Right now I'm thinking about one of the following:
Option A: Synthetic high milage oil such as Valvoline MaxLife High Mileage 5W-40
Option B: HDEO 10W/15W-40, such as Shell Rotella (or equivalent)

Right now, I leaning towards getting the Valvoline MaxLife 5W-40 for the Impala.

Is there a difference in the oils' capabilities to adhere to the cam lobes during the winter when it's not driven that often? Say one start-up every month, or every other month? I know some of you touched the subject, but are there any solid proofs that one oil sticks to the cam better than another oil?

Originally Posted By: BrocLuno

1.) pull a valve cover and look. Easy enough to do, and they are prolly weeping anyway.
We don't know which heads you have on that engine? Generator or alternator? Power steering?

I did pull a valve cover last year, and the rockers etc actually looked decent. Some minor 'sludge', but no solid deposits or other issues.
I don't know the casting number on the heads. Did GM use several casting numbers for the '65 283? It has an alternator and power steering, and I've converted it to a dual-circuit brake system with discs up front and a dual diaphragm booster. Oh, and AWG 1 ground cable from the battery to the block

Originally Posted By: BrocLuno

The reason I suggest looking for a nice used 327 is it's prolly one of Chevies best engines and they are getting hard to find. You can't just walk into a wrecking yard and grab a handful of 327's any more. There may be more surviving 283's ... The 327 got bought as a preferred replacement engine for cars/trucks getting long in the tooth, or as kids first hot-rod project many moons ago.
Your cylinder heads may be 1.72" intake valves with 1.50" exhaust. The better flowing 1.94" intake 327 heads were and easy swap on and they look almost identical on the outside. So if you could find a nice used/worn 327 you may get the better heads too

Then during rebuild, you could have hardened valve seats installed and not ever have to worry about valve regression from un-leaded gas.
I have an original carter 4-bbl cast iron intake manifold. I don't need to sell it. But if after playing with old girl some, you want up the anti and HP and find a donor 327, let me know and I'll ship it to you ...

I can't find a 283, or any other American V8 for that matter, on a wrecking yard here so that's not an issue.

If I find myself in need of say a yard-pulled small block or a crate big block, it's going to be shipped in a crate from the states anyway. Hardened valve seats, proper valve guides, roller hydraulic cam, chain oiling mods, roller chain etc, that's all on my 'must-have' list if I rebuild or get a new motor. A 327 would be nice, and I've been looking around for one. If I find someone, I might take you up on that manifold.
Originally Posted By: Nickdfresh
Originally Posted By: Berget
...
I thought that API SN puts a limit the zinc contents to 800ppm?

Not for 40W's, they can zinc it up all they want!!
Quote:
Originally Posted By: Nickdfresh
Can you get (Euro) Valvoline MaxLife High Mileage 5W-40? It would be perfect for this application IMHO...

Yes, it’s available for about 13$ / quart. What kind of synthetic is that, group III?

I'm not sure but my best guess is that its a blend of Group III/IV with more of the former than latter. So if $13 USD is really steep in Sweden, it might be more expensive than you need. As for being "duel rated", it's rated for gasoline engines, which is all that matters!

$13/quart is a normal price for a blend or cheap synthetic here. I just inserted the price to give you an estimate on the cost. Right now, I'm thinking about going for the MaxLife 5W-40…
Originally Posted By: Trav
Dropping a big block in this body is trade school kids stuff, almost zero fabrication work, that's the way I would go before messing around with small blocks in this size car, its needs a lot of torque to get the old lump shifting.

Big block, 383 small block, 327, 409, blown 350 etc. There are tons of options, but I'm not going down that road just yet. The 283 runs fine, and even though it might lack torque, it keeps the barge at pace with the rest of the traffic 
Originally Posted By: BrocLuno
Well stretching credulity some, let's say the engine wants a thick film when cold and before pumped oil is really circulating. The cam in this motor will have to live on residual cold oil film for a couple of minutes on start-up until the crank can sling enough new oil to replace. In that case 0W might be a bit thin, but so might 5W ...
283 Chevies from this era started and ran in Wisconsin all through teh 60's and 70's on 10W-30 w/o incident. Lots of them lived on SAE 30 HD as that's is what their buyers had grown up on. Long before synthetics were common, and with ridiculous amounts of VII's in cheap oil. They died not die. This one is still running, apparently well

Wisconsin and Sweden should have about the same starting conditions. Some folks from there should go ask Dad what he put in their old Chevy back then? 10W-30 up to about 100,000 miles and then 10W-40 till it dies was not uncommon. And we are discussing the finer points of 0W vs 5W ...

The recent years' climate change have treated us nice, especially when living close to the coast. Wisconsin actually has a colder climate than where I live. The monthly average temperature during the winter months puts my location in the same region as… Kansas. Not that I'm complaining

But you have a point on that 10W-30 was the go-to oil back in the days.
Originally Posted By: Carlostrece

Agreed. Based on what I've read about Valvoline 5W40 it should be good for his older car.
I'm currently using Penzoil Euro 5W40 in my older USA vehicle. I don't claim to be an expert, but I know a few things. It's working well for me. I'm also considering Shell Rotella T6 5w40 and Valvoline 5W40 for my two older cars.
I avoid 0W40 because I tried Mobil One 0W40 for 10,000 miles. It wasn't good in my older engines because it didn't hold it's viscosity. After about 2500 to 3000 miles the oil pressure dropped slightly, but noticeably. The oil seemed thinner. I change oil every 5000 miles, which is appropriate for my driving style of half city, half highway.
I would avoid any oils starting with 10W, 15W, or 20W oils because in your cold Swedish climate they'd be to thick at cold start, when you have to move the car in Winter, IMO.

Did you do an oil analysis afterwards? Did it shear down to a 0W-30, or even thinner?

 

[Dallas69]

Run 10-30 or 10-40 and forget about it

 

[FCD]

Valvoline Maxlife 5W or 10W-40 and forget about it.

 

[BrocLuno]

Is there any proof of film strength/thickness - not that I'm aware of. There are lower temp viscosity ratings that should be a good indicator

But, I'd just run an experiment in the back yard. Get a bit of flat metal and put some of your favorite synthetic on it and some HDEO like a 15W-40 ... Put it of the way for a week or so and go back and see what it looks like. Look at the underside. With the HDEO you will prolly see a thickish drop like film. Rub your finger across it, see how much comes off. Do the same with the synthetic ... If no different, you have your answer.

The cam will accumulate a thickish drop on the bottom of each lobe. When it rotates that will squeeze between the lobe and lifter face.

But the in-engine test is to install your oil of choice. Let it sit for a week or two and fire it up. If it clacks and clatters, it's not the right oil. If only a slight tick from the lifters until pumped oil reaches them, you are good to go. Testing is that simple. Formulas and such are great to discuss and really do mean something from an ultimate longevity stand point. But cold start compatibility is easy to test with your car as it is.

Since you pulled the valve covers and found not much, you have a clean engine. That is a great plus. It means that you are not fighting tons of varnish. In a 283, that is a god send

Just run a HM oil in the 10W-30/40 range that passes the cold start test. Any brand from any of the big refiners will be fine. The motor is simple and straight forward. No cam phasers, no cylinder de-activation, nada. High detergency would be nice to keep it clean. Seal conditioners would be nice. Nothing exotic. The HP density is not high enough to warrant the exotic stuff

As far as cylinder heads, sure Chevy had some different ones. The hot set-up for the 283 were the Power Pak heads. It's s fun subject to do some searches on. There is a message board for old car guys HAMB ( http://www.jalopyjournal.com/forum/forums/the-hokey-[censored]-message-board.5/ ) Lots of discussion of early cars. The cut-off is 1969 I think. Have not been there in a while. Plenty 283 guys and threads there

 

[Carlostrece]

If you can get Valvoline Maxlife 5W40 that would be an excellent oil, IMO. So would any 5W40 or 5W50 full synthetic, IMO.

Does Valvoline make a Maxlife 5W40? I've never seen any. I never heard of any either except in this thread.

Except that I would personally avoid Castrol and Royal Purple. I've read too many posts on muscle car forums of people who had their cams get ruined while using Castrol. I personally had that happen to me when I was using Castrol in a Honda motorcycle.

10W40 would be OK.

I would avoid 15W50 and 20W50 oils because IMO they're too thick at cold start, especially in your climate.

 

[Carlostrece]

Originally Posted By: Berget
I think I will ditch the M1 0W-40 for something else…

Right now I'm thinking about one of the following:
Option A: Synthetic high milage oil such as Valvoline MaxLife High Mileage 5W-40
Option B: HDEO 10W/15W-40, such as Shell Rotella (or equivalent)

Right now, I leaning towards getting the Valvoline MaxLife 5W-40 for the Impala.

Is there a difference in the oils' capabilities to adhere to the cam lobes during the winter when it's not driven that often? Say one start-up every month, or every other month? I know some of you touched the subject, but are there any solid proofs that one oil sticks to the cam better than another oil?

Originally Posted By: BrocLuno

1.) pull a valve cover and look. Easy enough to do, and they are prolly weeping anyway.
We don't know which heads you have on that engine? Generator or alternator? Power steering?

I did pull a valve cover last year, and the rockers etc actually looked decent. Some minor 'sludge', but no solid deposits or other issues.
I don't know the casting number on the heads. Did GM use several casting numbers for the '65 283? It has an alternator and power steering, and I've converted it to a dual-circuit brake system with discs up front and a dual diaphragm booster. Oh, and AWG 1 ground cable from the battery to the block

Originally Posted By: BrocLuno

The reason I suggest looking for a nice used 327 is it's prolly one of Chevies best engines and they are getting hard to find. You can't just walk into a wrecking yard and grab a handful of 327's any more. There may be more surviving 283's ... The 327 got bought as a preferred replacement engine for cars/trucks getting long in the tooth, or as kids first hot-rod project many moons ago.
Your cylinder heads may be 1.72" intake valves with 1.50" exhaust. The better flowing 1.94" intake 327 heads were and easy swap on and they look almost identical on the outside. So if you could find a nice used/worn 327 you may get the better heads too

Then during rebuild, you could have hardened valve seats installed and not ever have to worry about valve regression from un-leaded gas.
I have an original carter 4-bbl cast iron intake manifold. I don't need to sell it. But if after playing with old girl some, you want up the anti and HP and find a donor 327, let me know and I'll ship it to you ...

I can't find a 283, or any other American V8 for that matter, on a wrecking yard here so that's not an issue.

If I find myself in need of say a yard-pulled small block or a crate big block, it's going to be shipped in a crate from the states anyway. Hardened valve seats, proper valve guides, roller hydraulic cam, chain oiling mods, roller chain etc, that's all on my 'must-have' list if I rebuild or get a new motor. A 327 would be nice, and I've been looking around for one. If I find someone, I might take you up on that manifold.
Originally Posted By: Nickdfresh
Originally Posted By: Berget
...
I thought that API SN puts a limit the zinc contents to 800ppm?

Not for 40W's, they can zinc it up all they want!!
Quote:
Originally Posted By: Nickdfresh
Can you get (Euro) Valvoline MaxLife High Mileage 5W-40? It would be perfect for this application IMHO...

Yes, it’s available for about 13$ / quart. What kind of synthetic is that, group III?

I'm not sure but my best guess is that its a blend of Group III/IV with more of the former than latter. So if $13 USD is really steep in Sweden, it might be more expensive than you need. As for being "duel rated", it's rated for gasoline engines, which is all that matters!

$13/quart is a normal price for a blend or cheap synthetic here. I just inserted the price to give you an estimate on the cost. Right now, I'm thinking about going for the MaxLife 5W-40…
Originally Posted By: Trav
Dropping a big block in this body is trade school kids stuff, almost zero fabrication work, that's the way I would go before messing around with small blocks in this size car, its needs a lot of torque to get the old lump shifting.

Big block, 383 small block, 327, 409, blown 350 etc. There are tons of options, but I'm not going down that road just yet. The 283 runs fine, and even though it might lack torque, it keeps the barge at pace with the rest of the traffic 
Originally Posted By: BrocLuno
Well stretching credulity some, let's say the engine wants a thick film when cold and before pumped oil is really circulating. The cam in this motor will have to live on residual cold oil film for a couple of minutes on start-up until the crank can sling enough new oil to replace. In that case 0W might be a bit thin, but so might 5W ...
283 Chevies from this era started and ran in Wisconsin all through teh 60's and 70's on 10W-30 w/o incident. Lots of them lived on SAE 30 HD as that's is what their buyers had grown up on. Long before synthetics were common, and with ridiculous amounts of VII's in cheap oil. They died not die. This one is still running, apparently well

Wisconsin and Sweden should have about the same starting conditions. Some folks from there should go ask Dad what he put in their old Chevy back then? 10W-30 up to about 100,000 miles and then 10W-40 till it dies was not uncommon. And we are discussing the finer points of 0W vs 5W ...

The recent years' climate change have treated us nice, especially when living close to the coast. Wisconsin actually has a colder climate than where I live. The monthly average temperature during the winter months puts my location in the same region as… Kansas. Not that I'm complaining

But you have a point on that 10W-30 was the go-to oil back in the days.
Originally Posted By: Carlostrece

Agreed. Based on what I've read about Valvoline 5W40 it should be good for his older car.
I'm currently using Penzoil Euro 5W40 in my older USA vehicle. I don't claim to be an expert, but I know a few things. It's working well for me. I'm also considering Shell Rotella T6 5w40 and Valvoline 5W40 for my two older cars.
I avoid 0W40 because I tried Mobil One 0W40 for 10,000 miles. It wasn't good in my older engines because it didn't hold it's viscosity. After about 2500 to 3000 miles the oil pressure dropped slightly, but noticeably. The oil seemed thinner. I change oil every 5000 miles, which is appropriate for my driving style of half city, half highway.
I would avoid any oils starting with 10W, 15W, or 20W oils because in your cold Swedish climate they'd be to thick at cold start, when you have to move the car in Winter, IMO.

Did you do an oil analysis afterwards? Did it shear down to a 0W-30, or even thinner?


I did not do any lab tests on the Mobil One 0W40. My oil pressure became lower after 3000 miles with that oil. I did a Google search and found several people complaining about M1 0W40 having viscosity loss. I assume that's what was going on. I have never had that problem with any brand of 5W40. I run my oil to 5000 miles.

My 99 Jeep and 97 Buick both didn't like M1 0W40 past 3000 miles. It was fine from 0 to 2500 miles, or so. Then around 3000 to 3500 miles I noticed their oil pressures were lower than they used to be.

Both vehicles loved M1 Turbo Diesel 5W40 and now Penzoil Euro 5W40. They have noticeably better oil pressure at full operating temperature to 5000 miles. Then I change oil.

 

[Berget]

Originally Posted By: BrocLuno
But, I'd just run an experiment in the back yard. Get a bit of flat metal and put some of your favorite synthetic on it and some HDEO like a 15W-40 ... Put it of the way for a week or so and go back and see what it looks like. Look at the underside. With the HDEO you will prolly see a thickish drop like film. Rub your finger across it, see how much comes off. Do the same with the synthetic ... If no different, you have your answer.
The cam will accumulate a thickish drop on the bottom of each lobe. When it rotates that will squeeze between the lobe and lifter face.

I actually thought about doing that, mostly for fun. But would the amount of residue oil on the piece of metal tell the whole story? I'm speculating here, but if the 0W-40 reaches the cam (splash from the crank or draining from the lifter valley) is say 5 seconds, and it takes 30 seconds for a 15W-40 to reach the cam, could it be more beneficial to accept a thinner residue film on the lobe at startup?

Originally Posted By: BrocLuno
Since you pulled the valve covers and found not much, you have a clean engine. That is a great plus. It means that you are not fighting tons of varnish. In a 283, that is a god send

I wouldn't go so far as to call it a 'clean engine'

. There was some sludge present, and the so called valve seals (o-rings) are completely shot. I'm guessing they're mostly missing by now. It does smoke a bit when started after long periods of storage, and when going downhill at closed throttle, the vacuum sucks in some oil as well. I don't really care about the smoke (yet), because it will pass emissions anyway. I'm planning on changing the valve seals this spring. I'll go with the in situ technique which involves keeping the valves closed with compressed air while the springs and retainers are removed. I've done it before (on other engines) and it works fine, unless some [censored] disconnects the air hose because they need to dust of an air filter…

Originally Posted By: BrocLuno
But the in-engine test is to install your oil of choice. Let it sit for a week or two and fire it up. If it clacks and clatters, it's not the right oil. If only a slight tick from the lifters until pumped oil reaches them, you are good to go. Testing is that simple. Formulas and such are great to discuss and really do mean something from an ultimate longevity stand point. But cold start compatibility is easy to test with your car as it is.
Just run a HM oil in the 10W-30/40 range that passes the cold start test. Any brand from any of the big refiners will be fine. The motor is simple and straight forward. No cam phasers, no cylinder de-activation, nada. High detergency would be nice to keep it clean. Seal conditioners would be nice. Nothing exotic. The HP density is not high enough to warrant the exotic stuff

I'll try the cold start test before and after I change the valve seals. Right now, the plan is to run MaxLife 5W-40, and follow up with an oil analysis after the summer. If I'm not pleased with the results, I'll probably go for a 10/15W-40 HDEO, or some other similar solution (maybe with added ZDDP).

Originally Posted By: Carlostrece
Does Valvoline make a Maxlife 5W40? I've never seen any. I never heard of any either except in this thread.
Except that I would personally avoid Castrol and Royal Purple. I've read too many posts on muscle car forums of people who had their cams get ruined while using Castrol. I personally had that happen to me when I was using Castrol in a Honda motorcycle.

Me neither. But it's available at Valvoline's webpage: Valvoline MaxLife 5W-40
And an online store that sells them: http://www.mytyres.co.uk/cgi-bin/oshop.pl?item_id=443
I've never used Royal Purple, nor do I know of anyone who has. It's an American brand that appears to be mostly sold in the US, I guess. I'm no fan of Castrol, but I know it's widely used in Germany.

 

[BrocLuno]

Originally Posted By: Berget
Originally Posted By: BrocLuno
But, I'd just run an experiment in the back yard. Get a bit of flat metal and put some of your favorite synthetic on it and some HDEO like a 15W-40 ... Put it of the way for a week or so and go back and see what it looks like. Look at the underside. With the HDEO you will prolly see a thickish drop like film. Rub your finger across it, see how much comes off. Do the same with the synthetic ... If no different, you have your answer.

The cam will accumulate a thickish drop on the bottom of each lobe. When it rotates that will squeeze between the lobe and lifter face.


I actually thought about doing that, mostly for fun. But would the amount of residue oil on the piece of metal tell the whole story? I'm speculating here, but if the 0W-40 reaches the cam (splash from the crank or draining from the lifter valley) is say 5 seconds, and it takes 30 seconds for a 15W-40 to reach the cam, could it be more beneficial to accept a thinner residue film on the lobe at startup?


Ah, you are of the belief that pumped oil is good, pumping time is critical, and shorter is better... Well it is, but it ain't happening with this cam, except at the cam bearings. The lobes only gets sling oil off the spinning crank. And the crank only slings enough above about 1,500 RPM when it's warm and thin. Until then it's running mostly on residual film. It will sling some cold oil, but not as much by a long ways.

Valley drain oil does not land on most lobes ever. Notice that the engine is tilted back about 8* or so, so that the tranny will sit lower and the drive shaft does not need as big a hump inside the car. That rear tilt bias means that most valley oil runs down the back anyway, which helps lube the oil pump drive and distributor gears.

Valley oil comes back down the push rods, off the top of the lifters, and down from the head drain holes at either end. None of this is aimed at the cam in any way.

Older lifters will leak some down the outside and some will get on the cam, but not much, and that is dependent on varnish build-up too. Your lifters are not varnished-in (based on head condition), so that is helping

It's crude lubrication system. Effective enough most of the time, but it has issues ...