M1 0w40 or M1 HM 10w40? '86 T-Bird V8

[Inline200]

Hey guys, just looking for some opinions here for my '86 Thunderbird with a standard output 302. I bought it a few months ago with about 40,500 original miles on it. All tune-up items and filters have been changed and it runs great. It has no leaks that I can see, other than built up crud where the engine meets the transmission and the back bottom of the oil pan. The car is almost 30 years old so who knows what that's from or when.

I've only put on about 500 miles in almost 3 months with Penn. HM 5w30. I figured I'd use this as a precautionary clean up and have some extra seal conditioners in there while I get a feel for the engine's condition. I want to switch over to synthetic with a Mobil 1 filter and only do 1 change per year. I will maybe put on a few thousand enthusiastic miles within the year and make a few trips to run the car at the drag strip over that time. I really want to run the 0w40 but would like the extra peace of mind that the HM gives with the extra seal conditioners. Is the extra insurance of the HM oil worth it over using the 0w40?

Thanks!

 

[901Memphis]

The biggest advantage of the 0w40 is the extended change intervals. If you don't plan on running long drains the 0w40 isn't necessary.

I would use Mobil 1 High Mileage 5w30, which is thicker than a normal 5w30 and that is what your engine is spec'd for. The HM 5w30 has a HTHS Viscosity @ 3.3 and Viscosity at 100C @ 11.7 cSt, plenty for your 302 and then some.

 

[novadude]

Maybe M1 0W-40 isn't necessary, but for the same price as M1 5W-30, I can't see where it would hurt a thing. I agree that the M1HM in a 5W-30/10W-30 would be a great choice as well, but I think the 0W-40 is a higher quality oil, and I cannot see any downsides to running it. More HTHS, higher TBN, likely better basestock blend, etc.

 

[CATERHAM]

I'm with 901Memphis on this.
Stick with the 5W-30 grade, M1 0W-40 is a much heavier oil which you likely don't need if the engine is in good shape.

And if you're only going to be putting on maybe 1,000-1,500 miles per season then you could easily extend your oil change interval to at least 2 years.

 

[aquariuscsm]

I'd just keep on using Pennzoil 5W30HM.

 

[Inline200]

Originally Posted By: CATERHAM
I'm with 901Memphis on this.
Stick with the 5W-30 grade, M1 0W-40 is a much heavier oil which you likely don't need if the engine is in good shape.

And if you're only going to be putting on maybe 1,000-1,500 miles per season then you could easily extend your oil change interval to at least 2 years.


This sounds like a good idea. Maybe I'll go for the M1 5w30 HM with a M1 or Fram XG filter and go for more than a year. The car is driven at least once a week (probably will be a little less in the winter) so the oil flows regularly.

 

[CATERHAM]

There is no need to start the car up that frequently and it's better not to if you're not going to take the car for a run and get the oil fully hot. If the car is garaged over the winter, a few months in storage is no problem if the oil got good and hot when the engine was last run.

 

[OVERKILL]

I've had excellent results in the Ford Windsor with M1 0w-40. That, with an FL-1A Motorcraft filter is what I would run in your shoes.

 

[A_Harman]

M1 HM 5w30. Even though the car has low miles, the extra zddp couldn't hurt. I believe the '85 5-liter Ford still had flat tappets.

 

[OVERKILL]

Originally Posted By: A_Harman
M1 HM 5w30. Even though the car has low miles, the extra zddp couldn't hurt. I believe the '85 5-liter Ford still had flat tappets.


IIRC the engine went roller in '85 but didn't go SEFI until '86. Regardless, the OP's car is an '86, so it is roller.

 

[Boss302fan]

I would stay with Pennzoil 5W30 HM and see how that goes for the next 12 months. If you only drive it 2K miles in 12 months, I would do a once a year OCI...

 

[strat81]

Aside from the seal conditioners, I don't see much advantage to M1 HM 10W-40 over M1 0W-40. If you don't have any leaks, I wouldn't sweat not having those seal conditioners in there.

M1 0W-40 is excellent oil, but if you don't "need" it for its performance/protection benefits such as extended drains, oxidation resistance, add pack, etc., any name brand oil, conventional or synthetic, would work fine.

 

[novadude]

Originally Posted By: CATERHAM
I'm with 901Memphis on this.
Stick with the 5W-30 grade, M1 0W-40 is a much heavier oil which you likely don't need if the engine is in good shape.

And if you're only going to be putting on maybe 1,000-1,500 miles per season then you could easily extend your oil change interval to at least 2 years.


"Much heavier"? Can't say I agree with that, and I also don't think moving from a heavy HM 30wt to a light 40wt 0W-40 will hurt anything at all. Reegardless, I'm sure it doesn't NEED 0W-40, but I can't see any real downside to running it.

Car was likely spec'd for a 10W-30 when new. ZDDP could still be a good thing, roller cam or not. This engine still has the old style rocker arm pivots that are not roller.

 

[Shannow]

Originally Posted By: novadude
Originally Posted By: CATERHAM
I'm with 901Memphis on this.
Stick with the 5W-30 grade, M1 0W-40 is a much heavier oil which you likely don't need if the engine is in good shape.

And if you're only going to be putting on maybe 1,000-1,500 miles per season then you could easily extend your oil change interval to at least 2 years.


"Much heavier"?


Yeah, that's what I thought.

with 1,000 miles per season, then the improved cold cranking, and hot viscosity margin the 0W-40 provides would make any possible fuel savings from the 5W-30 HTHS massively meaningless.

 

[901Memphis]

Originally Posted By: Shannow
Originally Posted By: novadude
Originally Posted By: CATERHAM
I'm with 901Memphis on this.
Stick with the 5W-30 grade, M1 0W-40 is a much heavier oil which you likely don't need if the engine is in good shape.

And if you're only going to be putting on maybe 1,000-1,500 miles per season then you could easily extend your oil change interval to at least 2 years.


"Much heavier"?


Yeah, that's what I thought.

with 1,000 miles per season, then the improved cold cranking, and hot viscosity margin the 0W-40 provides would make any possible fuel savings from the 5W-30 HTHS massively meaningless.



The 5w30 is superior at cold cranking until the temperatures go negative.

 

[CATERHAM]

The other reason why running a 40 grade, even M1 0W-40 would undoubtedly prove too heavy is Ford's relatively low oil pump relief setting (IIRC 65 psi), consequently you'll likely never get the oil temp's hot enough to be out of by-pass mode at elevated rev's with a 40 grade oil. The specified 30 grade for the V8 of the day wasn't that heavy with a HTHSV in the 3.0-3.3cP range and that's before any shearing, so it would likely prove counterproductive to run an oil much heavier than that. In fact I wouldn't be surprised if a shear stable 5W-20 like QS Defy 5W-20 wouldn't maintain sufficient oil pressure at the normal oil temp's encountered in a street driven car.

 

[Inline200]

Originally Posted By: CATERHAM
The other reason why running a 40 grade, even M1 0W-40 would undoubtedly prove too heavy is Ford's relatively low oil pump relief setting (IIRC 65 psi), consequently you'll likely never get the oil temp's hot enough to be out of by-pass mode at elevated rev's with a 40 grade oil. The specified 30 grade for the V8 of the day wasn't that heavy with a HTHSV in the 3.0-3.3cP range and that's before any shearing, so it would likely prove counterproductive to run an oil much heavier than that. In fact I wouldn't be surprised if a shear stable 5W-20 like QS Defy 5W-20 wouldn't maintain sufficient oil pressure at the normal oil temp's encountered in a street driven car.


That's interesting. It seems like everyone with a 5.0 is running thicker than 10w30. On my past 302's I've never gone beyond 10w30, but I've always heard that going above the factory spec. 5w30 was the norm on these engines.

 

[Jaymus]

I run T6 5W-40 or M1 0W-40 in the cold winter in my old 86 flat tappet 5.0. I just feel safer with the extra zinc and phosphorous. I'm not declaring anything other than it has done fine with it for the last seven years lol.

 

[CATERHAM]

Originally Posted By: Inline200
Originally Posted By: CATERHAM

That's interesting. It seems like everyone with a 5.0 is running thicker than 10w30. On my past 302's I've never gone beyond 10w30, but I've always heard that going above the factory spec. 5w30 was the norm on these engines.

And some may have a legitimate reason if the bearings are well worn in an original 25-30 year old engine but most don't even know what's the oil pressure of their engines. They've heard older engines need heavier oil so that's how these myths get started.

 

[Clevy]

Originally Posted By: OVERKILL
Originally Posted By: A_Harman
M1 HM 5w30. Even though the car has low miles, the extra zddp couldn't hurt. I believe the '85 5-liter Ford still had flat tappets.


IIRC the engine went roller in '85 but didn't go SEFI until '86. Regardless, the OP's car is an '86, so it is roller.



I think overkill is right here.
Not that it really matter. Elevated zinc only really matter when breaking in new parts. Once the metal is wear/work hardened more zddp isn't needed.
And let's get serious here. It's a stock 302,from the mid 80s.
It's not like the spring rates are very high. I bet you could squeeze the valve springs between your fingers.
And from experience,last year driving that 88 for a few months(before stripping it for parts for the Capri) I can say without a shadow of a doubt the oil gets blistering hot.
For example in all my vehicles I can shut them off at the gas pumps and check the oil level,once I turn on the pump,and in that 88 the oil was so hot at shut down it seriously burned my fingers,and the dipstick was also blistering hot.
No other vehicle I've owned in recent years gets the oil that hot and even my charger isn't that hot,and the oil temp gauge is reading over 200f,and still didn't burn like the 5.0 in that 88.
So let's consider that the t-bird is a bit heavier,even though it's built on a fox platform,which is more likely to be working the engine harder and therefore elevating the oil temps even higher than what I was experiencing.
Knowing all of this I'd run a 40 grade. If you want to extend the interval then use a euro grade oil.
I tried out using a 5w-20 in that engine before we stripped the car. I've got the engine in my garage waiting for a transplant and I will say this,that the engine was more responsive at light throttle inputs using a 5w-20. Had more pep.
But with the pedal on the floor I couldn't tell the difference between 5w-20 or 20w-50,if it matters to anyone.