Recommended oil for 1975 Cadillac Eldorado 500 CID

[Garak]

Originally Posted By: Merkava_4
20W-50 would lubricate those flat bottom lifters and protect the cam lobes. It would also keep those same hydraulic lifters pumped up. Y'all try running 5W-30 in that vintage iron and you're gonna get clickity clack from the lifters bleeding out.

I've run nothing but ILSAC type 30 grades in small block and big block engines of that vintage. I'd run some Defy 5w-30, or, at the outside, a 10w-30 VR1. There would also be nothing wrong with a reasonable HDEO in this application.

Did you know that Mobil yanked anything heavier than a 10w-30 (aside from Euro and motorcycle oils) in Canada many years ago? They don't even offer a 10w-40 up here, let alone a 20w-50.

 

[aquariuscsm]

Maybe try something like this:

http://www.jegs.com/i/Lucas+Oil/639/1068...CFU4R7AodjnoAMA

http://www.classiccarmotoroil.com/

 

[Garak]

I bet the VR1 is cheaper. Walmart up here, for some reason, prices it about the same as other conventionals. But, they only stock 20w-50, so you can imagine how well that moved over the winter.

 

[Merkava_4]

Originally Posted By: Garak
I've run nothing but ILSAC type 30 grades in small block and big block engines of that vintage. I'd run some Defy 5w-30, or, at the outside, a 10w-30 VR1. There would also be nothing wrong with a reasonable HDEO in this application.

Did you know that Mobil yanked anything heavier than a 10w-30 (aside from Euro and motorcycle oils) in Canada many years ago? They don't even offer a 10w-40 up here, let alone a 20w-50.

I'm the only one in this thread that has real world experience with a Cadillac 425 CID V8 and 20W-50.

If 20W-50 is not the perfect oil for the OP's Cadillac, may lighting strike me dead right now!!

 

[turtlevette]

Widely varying recommendations. Clashing philosophies.

And everyone is absolutely sure they're right.


Car forums are full of greatness.

 

[Garak]

Originally Posted By: Merkava_4
If 20W-50 is not the perfect oil for the OP's Cadillac, may lighting strike me dead right now!!

And if it is, may lightning strike me dead right now. See, we're even.

 

[Merkava_4]

Originally Posted By: Garak
And if it is, may lightning strike me dead right now. See, we're even.


In that case, I'd advise you to stay away from tall metal structures for the next few days.

 

[Garak]

I'll hide in the basement in the interim.

 

[Vspec]

Id run a 0w20, or when Honda releases the 0w16, that would be a good choice.

 

[dave1251]

Originally Posted By: Fraser434
Still needs plenty of ZDDP. VR1 or Rotella be good.


Sorry PCMO's of this vintage had anywhere from 500 to 1200 parts per million of ZDDP. So plenty of ZDDP was not used. I would believe after 45 years anti-wear, friction modification, dispersant, detergent, and balanced formulation has at the very least improved somewhat.

 

[bigt61]

ZDDP is only a big deal when you run high spring pressure on a flat tappet cam, like Nascar engines or '60s muscle cars. That Caddy engine has a low lift cam and is very under stressed, I doubt you could go wrong with any modern oil. I'd run cheap SuperTech 10W-30 and change it every few years. If it leaks a little, just use MaxLife red bottle or any HM 10W-30.

 

[fdcg27]

Originally Posted By: turtlevette
Widely varying recommendations. Clashing philosophies.

And everyone is absolutely sure they're right.


Car forums are full of greatness.



Everyone probably is right in that this big, lazy engine would be just fine on any of the oils recommended in this thread.
This engine has a specific output similar to that of the normally aspirated W115 diesels that were contemporary to it.
That's pretty low.
Back in the day, many people who thought that they knew better used 10W-40 in every application.
I did.
Some even favored 20W-50 and ran it for many miles in a variety of engines with no ill effects, at least not in warm weather.
In really cold weather, a really thick oil could cause the oil pump drive to shear at cold starts.
Anyway, if I were the OP, I'd run any 10W-30, as I originally posted in this thread.
If the OP wants to take the advice of some others and use something much thicker in the warm conditions in which this car will likely be driven, since I can't imagine that the car is stored outside and used a a winter beater, then while it may not be an improvement, it won't do any harm.
Most engines will do just fine on a variety of grades.

 

[Boss302fan]

If it was my car, I would start with 10W30 Rotella and then possibly go with QS Defy in a 5W30 weight...

 

[NEPA_Z]

The big Cads really had very light spring pressures; something like 70lb on the seat and < 200 open iirc. Peak power was made well under 4000 RPM so they didn't have to spin much. When I took my first one apart I remember being amazed that I could open the valve with my thumbs on the retainer. Still, I believe the BOC base circle is quite small relative to other engines so that may be an aggravating factor.

Here's my '72 472 that I pulled for a cosmetic resto some years ago. It had about 67k miles and was very clean inside, with a stack of the original owner's oil change receipts in the glovebox: Sears Spectrum 10W30 and 10W40. Even the nylon cam gear was completely intact.

It went back in with some head work and a Comp cam with stouter springs, about 100 / 280. I run PYB 10W40 and add some ZDDP.

 

[Zaedock]

Originally Posted By: Merkava_4
Originally Posted By: Garak
I've run nothing but ILSAC type 30 grades in small block and big block engines of that vintage. I'd run some Defy 5w-30, or, at the outside, a 10w-30 VR1. There would also be nothing wrong with a reasonable HDEO in this application.

Did you know that Mobil yanked anything heavier than a 10w-30 (aside from Euro and motorcycle oils) in Canada many years ago? They don't even offer a 10w-40 up here, let alone a 20w-50.

I'm the only one in this thread that has real world experience with a Cadillac 425 CID V8 and 20W-50.

If 20W-50 is not the perfect oil for the OP's Cadillac, may lighting strike me dead right now!!


LOL

I have experience with 425's, 472's, and 500's. Won't even mention the Pontiac or Olds motors I've done.

A 30 grade lubricant in this engine is perfectly fine.

 

[A_Harman]

Originally Posted By: NEPA_Z
The big Cads really had very light spring pressures; something like 70lb on the seat and < 200 open iirc. Peak power was made well under 4000 RPM so they didn't have to spin much. When I took my first one apart I remember being amazed that I could open the valve with my thumbs on the retainer. Still, I believe the BOC base circle is quite small relative to other engines so that may be an aggravating factor.



Yes, Wikipedia has a chart of performance specs for the Cad 500. It started in 1970 with 400 HP @ 4400 rpm, and 550 ft*lbs @ 3000. In 1971 the compression ratio was reduced from 10 to 8.5, and power dropped to 365. It was all downhill from there, with power dropping to 235 in 1972. I'm skeptical of the Wikipedia table in that it shows peak power speed of 4400 up to 1974, when it dropped to 3600. It seems like the rpm should have dropped in 1972, when the engine lost 130 HP. By 1976 the engine was down to 190 HP, after which, it was mercifully put out of its misery.

 

[NEPA_Z]

Yes, I should have pointed out the earlier engines had higher-rpm power peaks. I have '69 and '72 472s, and the '69 feels much stronger than did the '72 when it was stock. I've never put a tach on the '69 to see where it shifts; I'll add that to my list of stuff I need to get to.

 

[aquariuscsm]

Originally Posted By: Garak
I bet the VR1 is cheaper. Walmart up here, for some reason, prices it about the same as other conventionals. But, they only stock 20w-50, so you can imagine how well that moved over the winter.


^^I forgot about that one. VR1 20W50 would be my recommendation. Plus it`s CHEAP! Isn`t it about $4 a quart at all the chains?

 

[fdcg27]

Right, and VR1 10W-30 would be the same price.
A little more zinc and phosphorous than an API SN oil, for those who think it's needed.
Is the conventional VR1 dyed the same pretty shade of blue as the synthetic?

 

[aquariuscsm]

Originally Posted By: fdcg27
Is the conventional VR1 dyed the same pretty shade of blue as the synthetic?


Nope. The conventional VR1 is amber like all other oils.