Oil for my classic Cadillac?

[mojogator]

Thanks for all the replies guys - the car has Castrol 5W30 in it now - I had that here already and figured it was better than the old black oil that was in the car when I got it. I'm probably going to change to a 10W40, still researching as to which brand...

Originally Posted By: mechtech2

The cooling system is not made for that engine or AC, so make sure you have a large radiator, and good fan and shrouding.


Thanks - but you're preaching to the choir on that one - efficient cooling systems are a top priority in all my projects. When I got the car it had a 15" flex fan and no shroud. Replaced that with a 19" 7 blade fan and built a shroud. I hung the flex fan on the wall with about 3 others I've taken off cars. It has the '70 Cadillac radiator in it so it should be plenty big.

 

[ARCOgraphite]

Originally Posted By: D189379
Originally Posted By: NateDN10
Originally Posted By: D189379
Mobil 5W20 just to be different.

And for no other reason.


And because nobody will come up with a "proven" reason not to.
That'S because the proof caN BE COSTLY.

 

[Trvlr500]

Originally Posted By: D189379
Mobil 5W20 just to be different.


You're kidding right?! That'll get him into a rebuild in no time at all.

 

[Trvlr500]

I have a '73 Caddy with a 472. I'm using Rotella T 5-40 in it only because where I live it gets pretty cold in the winter. I ran Mobil 1 15w50 for 10 years in it. Considering where you live an HDEO 15-40 would work fine. I know a Caddy owner/Mechanic up in Canada that uses 15-40 in all his Cads. The 15-40 will give you the ZDDP you need as well.

I'd stay away from ANY of the oils with that ridiculous starburst or "energy saving" on the bottle for THAT engine. That's not a sewing machine engine you have. Most all the Caddy buffs I talk to are running a 15-40 HDEO like Rotella, Delvac or Delo. The T-6 5-40 has worked quite well for me whether it's 100 degrees outside or 0 degrees.

Those 472's have notoriously low spring pressures on the valves but you still need ZDDP in that engine for other reasons. They also run pretty hot. At least mine does. The 70's may run cooler I don't know but the later 472's were designed to run hotter just like newer cars do.

 

[A_Harman]

50/50 blend of Valvoline VR1 10w30 and 20w50.

Also, you could consider taking the engine-driven fan off and installing an electric fan on the radiator. Spal makes such setups. This would be a good way to save fuel at highway speeds by not having to drive the fan.

 

[mechtech2]

Originally Posted By: fdcg27
IIRC, GM was no longer specing 10W-40s in 1970, and was specifically warning against their use.
The original requirement for that engine was probably 10w30.
This is a pretty mild engine by any standard.
The Caddy engines made their power at low revs, since they were certainly of the big displacement school, and had modest specific output.
I think a conventional 10w30 would be okay in this engine, although a modern 10W-40 or 15w40 might be better.
Any oil you'll put in it now is far better than the best oil that could have been found in 1970, though.
Having said all of the above, if it were mine, I'd give it either Mobil 1 High Mileage 10w40 or Mobil 1 15W-50, or at least Maxlife SB 10W-40.



GM certainly DID approve of 10-40s in 1970 and beyond. It was what they had to work with.

 

[SS1970chrysler]

Originally Posted By: mechtech2
Originally Posted By: fdcg27
IIRC, GM was no longer specing 10W-40s in 1970, and was specifically warning against their use.
The original requirement for that engine was probably 10w30.
This is a pretty mild engine by any standard.
The Caddy engines made their power at low revs, since they were certainly of the big displacement school, and had modest specific output.
I think a conventional 10w30 would be okay in this engine, although a modern 10W-40 or 15w40 might be better.
Any oil you'll put in it now is far better than the best oil that could have been found in 1970, though.
Having said all of the above, if it were mine, I'd give it either Mobil 1 High Mileage 10w40 or Mobil 1 15W-50, or at least Maxlife SB 10W-40.



GM certainly DID approve of 10-40s in 1970 and beyond. It was what they had to work with.


I want to say it was around '84-'85 that they started advising away from 10w-40. My owners manual for an '85 Delta 88 says something about avoiding 10w-40 due to results of a study GM did on '84 models. They recommended either 10w30 or 15w40 in its' place.

 

[mojogator]

Thanks for the replies everyone. After reading them all and doing a bit more research here I decided on the Rotella 15W40 HDEO. It's plenty cheap and gallon jug is just the amount I need for an oil change including the filter.

 

[D189379]

Originally Posted By: Trvlr500
Originally Posted By: D189379
Mobil 5W20 just to be different.


You're kidding right?! That'll get him into a rebuild in no time at all.


Kidding about using 5W20 oil? Why would I?

Have you ever seen 5w20 oil used in a Cadillac causing an engine rebuild? I'm guessing not.

 

[A_Harman]

That may be true, but the thing is, I've never heard of anybody running 5w20 in a vintage Cadillac engine, period.

 

[crazyoildude]

Rotella
and do not use 5w20 in that engine...Those engines last a long time on heavier oil...Be careful those engines Will have balance problems when rebuilt unless the shop you use balances that engine very carefully those 368 425 472 and 500 can have those problems

 

[Trvlr500]

Originally Posted By: D189379
Originally Posted By: Trvlr500
Originally Posted By: D189379
Mobil 5W20 just to be different.


You're kidding right?! That'll get him into a rebuild in no time at all.


Kidding about using 5W20 oil? Why would I?

Have you ever seen 5w20 oil used in a Cadillac causing an engine rebuild? I'm guessing not.


I'm VERY late with a response but no and the reason is that no one with a 472/500 would be foolish enough to do it. The 472/500 WAS built with extremely tight tolerances for it's day but Cadillac recommended 30 weights back then. A 5-20 on a hot day across the desert at high speeds would most probably fry the engine especially if you were towing with it.

There is a reason most that still own these vintage Caddy's use a 15-40. Granted, most have been rebuilt due to neglect as mine was and the tolerances are "looser" but even a stock engine needs a 30 weight. I only use the 5-40 because it gets very cold where I live.

As for hearing about it if it did happen you probably wouldn't since the following for early 70's Cads is small and as I said before. No one would do it if they had half a brain.

 

[Merkava_4]

Based on my experience with the Cadillac 425, and for the smoothest
operation and best fuel mileage, 20W-50 Valvoline is what I'd use.