1968 Cadillac

[Mike68]

Hi guys
I recently purchased a 1968 Cadillac Fleetwood with about 80,000 miles on it and was wondering what was the best weight oil to use.Is 10w30 ok or should I be looking at something heavier.Car is going to be a weekend cruiser so not much long distance driving.Thanks for any help you can give me.

 

[G-MAN]

Assuming the engine is all original, I'd use Maxlife 20w50 year round and change it every 6 months regardless of mileage.

 

[eljefino]

I'd go with HDEO 15w40 changed once a year.

A xw30 weight is "okay", but you might get fuel dilution screwing around with the car.

Pics?

 

[Michael_P]

I would use Rotella T5 10W30. Those 68's had hardened valve seats and other modern things like that which made 10W30 acceptable. Before I go recommendation crazy, what engine is in there. I had an old 8.2L in an Eldorado.

 

[sasilverbullet]

I use Chevron Delo 20-40 in my 70 Lincoln. It has all the right ingredients for our older, big iron v-8's.

 

[Bluestream]

I would use GC 0W30. It won't let you down.

 

[Mike68]

Thanks for all the replies.It has the 472ci and as far as I know it is all original.I don't have any pics yet as it has been raining here all week but this weekend I will be outside with my camera.

 

[G-MAN]

Originally Posted By: Michael_P
I would use Rotella T5 10W30. Those 68's had hardened valve seats and other modern things like that which made 10W30 acceptable. Before I go recommendation crazy, what engine is in there. I had an old 8.2L in an Eldorado.


Hardened valve seats don't have anything to do with the weight of oil to be used.

I think 68 was the first year for the new 7.7 liter (472 CID) engine, which was stroked to 8.2 liters (500 CID) for the 1970 Eldorado.

 

[Mike68]

Thats right G-Man.1968 was the first year for the 472.Before that they had a 429.Living in New York would I have a problem with the 20w-50 being too heavy in the winter months?

 

[Rob_Roy]

You plan to drive a 68 Caddy in NY winters?? Not in the salt I hope!

15w40 will serve you very well.

 

[river_rat]

I think it called for 10w30 when new. If so, possibly Brad Penn 0w30 Penngrade 1.

 

[dlafoy]

Partially hydrogenated cottonseed oil

 

[Brons2]

I vote for 15w40 also, and don't drive it in the wintertime.

 

[Merkava_4]

20W-50 Exxon Superflo!! I'm serious. I had a 1978 with the 425 and it LOVED 20W-50. Quiet engines = well lubricated engines and that engine was the quietest with 20W-50 Superflo. All you could hear were the belts rolling over the pulleys.

 

[Jim Allen]

Big engine, thick oil, huh? Don't see the logic in that.

My advice is to look to the original recommended base viscosities as a strong guide. They knew what they were doing. Look next to match the ZDDP content of the original oil as closely as you can. That's most easily and cheaply done with an SM/CJ4 dual rated HDEO oil. More than likely, 10W30 was the "all-climate" viscosity choice back then, so you could go that way and a high zinc 10W30 HDEO like the T5 Rotella syn blend or the plain 10W30 Rotella Triple Protection would be great. Either of these two oils would be better than what was offered in 1968. If the Chevron, Mobil or any other 10W30 HDEO is available in your area, they would be good too. I mentione the Rotella brand because it seem to be most readily available (such as at Wal Mart). I also like the HDEOs for their robust antioxidant additive packages, which make them a good choice for a car that will not be driven daily. Makes one, two or three year OCIs possible if the annual mileages are low.

Going back to the ZDDP content, I think you can "get by" with SM, especially for a non daily driver, but why not go with the sure thing. If you could find an API SL in 5W30, that big Caddy would love you for it... though it's likely the engineers designed around a 10W30.

Good luck with your cool ride!

 

[addyguy]

Rotella 10w30 all the way on that beauty.

 

[Mike68]

Thanks guys for all the help.

 

[G-MAN]

Originally Posted By: Jim Allen
Big engine, thick oil, huh? Don't see the logic in that.


My recommendation of of 20w50 Maxlife was not based on the size of the engine. You've got 43 year old engine, with 43 year old seals, a 43 year old oil pump, and 43 year old rings. With 80,000 miles on it, that engine has averaged less than 2000 miles a year so I'm sure it's not pristine on the inside. 20w50 will ensure adequate oil pressure and ring seal, and the conditioners and detergents in Maxlife will be good for this ancient big block.

 

[crazyoildude]

I have a 70 de ville convertible with the 472 and it has under 40,000 original miles in near showroom condition and i use 10w30 high mileage pennzoil mainly because of the seals so far so good there are no leaks and engine runs great! The transmission had bad seals from sitting in a garage and would not shift well and also leaked i poured 1/4 quart of brake fluid into the trans and in two weeks and about 100 miles i changed the fluid and filter and used high mileage fluid and the seals sweeled up and everything is perfect one year later

 

[Merkava_4]

Originally Posted By: Jim Allen
Big engine, thick oil, huh? Don't see the logic in that.


The logic is that works and works very well in a Cadillac OHV V8 engine.