Need rec, for a 1966 Shelby GT350 clone

[VVTinme]

A good friend of mine will be getting a 1966 Shelby GT350 clone tomorrow that he has waited over a year for. The person who built the car recommended he use 20W50 oil. That seems awful thick to me, so I am wondering if that is correct, or if he should use something different altogether. Also, recommendations on OCI, filters, brands, etc. are also welcome. Here is information of the engine:

Rebuilt 1967 289 smallblock
Hydraulic lifters
Mild cam upgrade

If there is anything else you need to know, just ask, and I'll forward your question on to my friend. Thanks!

 

[Dyoel182]

That is awfully thick and I bet the person who built the car has a house that still looks like 1966 if he's stuck that far back in the past.

 

[Johnny]

Well, back in 1966 I ran 20W40 in my 65 Shelby, but no one makes 20W40 anymore. Being in NC I would not have a problem with using a good 20W50. But, if it were mine now, I would break it in on a good mineral 20W50 (either Castrol or Valvoline) since those are the two you will find on the shelf, the I would run Mobil 1 15W50 in it. Or I would contact one of the site sponsors and run Amsoil 20W50 in it. Those old 289's liked thick oil and I know it won't be babied. When your friend gets this nice reproduction we expect to see pictures of it.

 

[Gary Allan]

Quote:
but no one makes 20W40 anymore.


At least not with a "S" rating. All that I've seen are for locomotive diesel apps and only carry the CF/CF2 ratings.

I do recall Arco 20-40 fleet oil in the 70's. I guess this was the predecessor to our contemporary 15w-40 lubes. Back then I was scraping up change to keep oil in the worn 61 SBC back then.

 

[Rock_Hudstone]

Originally Posted By: sonyman
The person who built the car recommended he use 20W50 oil. That seems awful thick to me, so I am wondering if that is correct.If there is anything else you need to know, just ask, and I'll forward your question on to my friend. Thanks!

I'd pass on the 20w-50 as well.

If this is a flat tappet engine the typical passenger car oil on the shelves these days will not have enough ZDDP anti-wear additive for the cam and lifters to survive, (including most 20w-50 weights). He should use a heavy-duty diesel 15w-40 motor oil: Shell Rotella, Chevron Delo, Castrol GTX Diesel, or even the Walmart SuperTech universal.

If he wants to go with a full synthetic the Mobil 1 15w-50 or Shell Rotella-T 5w-40 are very good as well and widely available at Walmart or the major auto parts stores.

 

[Rock_Hudstone]

Forgot to mention, I like the AC-Delco filters, very good quality and reasonably priced. By the way, Autozone has great special going on now; 5 qt. Castol GTX and a oil filter for $10.99, (GTX 15w-40 Diesel included).

 

[VVTinme]

I don't believe he really cares about synthetic vs non-synthetic. His original plan was to run Valvoline dino, before he even heard from the car builder, since he tells me that was [the good stuff] back then. Also, as far as reaching a consensus, it seems that for the most part, you are all telling me that a 40 weight would be best. Narrowing that further, Rock_Hudstone, you mention using both 5W40 and 15W40 depending on my friend's preference. Is there a reason why you rank 15W40 above 5W40? Also, how can one tell if it's a flat tappet engine or not? I may not be able to get ahold of him until Sunday due to our conflicting work schedules.

 

[Merkava_4]

Quote:
The person who built the car recommended he use 20W50 oil.


Is that the same guy that built the engine? What about the machinist, what does he recommend for oil? Typically on a vintage American V8 you'd run SAE 30 for the first 20 minutes; drain that out, run another fill of SAE 30 for 300-500 miles; drain that out and then go strait to 15W-40 or 20W-50 depending on what the machinist recommends.

 

[Rock_Hudstone]

Originally Posted By: sonyman
I don't believe he really cares about synthetic vs non-synthetic. it seems that for the most part, you are all telling me that a 40 weight would be best. Narrowing that further, Rock_Hudstone, you mention using both 5W40 and 15W40 depending on my friend's preference. Is there a reason why you rank 15W40 above 5W40? Also, how can one tell if it's a flat tappet engine or not?

I wasn't ranking 5w-40 above 15w-40, I just happened to type it in that order and divided the synthetics from non-syn oil. Don't get too hung up on the viscosites, the more important thing is ZDDP levels and those particular weights have higher amounts than others.

Flat tappets or valve lifters have a flat face that slides on the cam lobe as opposed to roller lifters. ZDDP anti-wear additives are crucial to the former because of the extreme pressures at the cam lobe/lifter.

 

[Pablo]

I'd run a fully additized synthetic SAE 30 or 15W-40. A synthetic 20W-50 will probably be fine, but a petroleum 20W-50 is sluggish when cold, even on marginally cool days.

 

[VVTinme]

I believe the person who built the car built the engine as well, but I don't personally know the specifics. It was built at the Mustang Ranch, in Fresno, California, if that helps at all. The car has already been driven a few miles (less than 50 by my estimates) wth 20W50 in it, but I don't know if something else was used when it was first assembled. If he follows a break-in procedure with SAE30, what is a good oil to use? Or is it too late? Later, when he puts in the post-break in oil (or just changes it if it's too late), what is a good 15W40 oil that offeres the necessary protection. Furthermore, would SAE30 be better than 15W40, or vice-versa?

 

[Merkava_4]

The thin 30 weight oil during the break in process is primarily used to seat the piston rings to the cylinder walls and to break in the camshaft. But depending on how tight the clearances were set up during the machining process, a 30 weight could be used longer. I don't know why they chose to go to a 20W-50 so early on, but they might have some kind of reasoning behind it.

As far as brands go, there's really not much difference; it's mainly a personal preference based on trust between the consumer and the oil company. My own personal preference for an engine like this would be either Valvoline, Castrol or Chevron for both SAE 30 and 15W-40.

 

[VVTinme]

I just spoke with him over the phone. It turns out that the engine does indeed have a break-in oil in it now, which I assume to be SAE30. It also does indeed have flat tappets. Finally, he mentioned that the car builder said specifically not to use synthetic oil as it would eat away at the seals. IMO, that's probably based more on myth than fact, but I have a feeling he'd rather use a dino oil anyway. Having established all this, I also have a feeling that a 40-weight would be best, since that falls in the middle of SAE30 vs 20W50, the builder's recommendation. This brings me to one last question (for now), what oils provide adequate protection since we now know it has flat tappets?

 

[kapps]

GTX 20w-50 still has the zddp needed for flat tappets. Valvoline VR1 has even more.

 

[Johnny]

Well, since he wants to stick to mineral oils and a 15W-40 I would recommend three that are easy to come by.

Shell Rotella T
Chevron Delo 400
Mobil Delvac 1300

And my personal preference would be in that order. Do you know or can you find out what oil the builder recommends? That would be interesting.

 

[Johnny]

Originally Posted By: kapps
GTX 20w-50 still has the zddp needed for flat tappets. Valvoline VR1 has even more.


If you go this route, I could highly recommend Pennzoil GT Performance 25W-50. An excellent oil for those flat tappets.

 

[Pablo]

Quote:
Finally, he mentioned that the car builder said specifically not to use synthetic oil as it would eat away at the seals. IMO, that's probably based more on myth than fact...


This is sort of a common myth....and you seem to know it's complete garbage, plus I don't want to bog down this thread with a seal vs. oil debate - however all that said - I always wonder what other myths, misconceptions, mistakes the car builder incorporates into his product......

 

[VVTinme]

I'm fairly sure the person who assembled the car and the builder are one and the same, but I'll try to get confirmation on that. Now I'm curious though, which would actually be better, the 20/25W50 oils or one of the 15W40 oils listed above?

 

[Merkava_4]

One of those oils that Johnny listed would be excellent, but I'd still leave the break-in oil in there for 500 miles.

 

[VVTinme]

I know for a fact that my friend does plan on leaving the oil in for the break in. Just to clarify, all the oils Johnny listed have high ZDDP for the flat tappets?