What wate of oil do you use in your big block? My self im using W 10/30.

I used 10W-30 in my 425.... if i had to do it again I would use Mobil Delvac 15W-40

I use straight 30 weight whenever possible, for some reason I have a hard time finding it sometimes. If I can't get 30W I get 10W-30... but it really does seem a bit thin for these engines.

I use straight 30 weight whenever possible, for some reason I have a hard time finding it sometimes. If I can't get 30W I get 10W-30... but it really does seem a bit thin for these engines.


eldorado99 You can try to get hold of it via a store for heavy equippment. I know that straight 30 motor oil is demanded and used in some heavy equippment as hydraulic oil.
I dont know what size container that is aviable but maybe 20liter.

jolle

eldorado99 You can try to get hold of it via a store for heavy equippment. I know that straight 30 motor oil is demanded and used in some heavy equippment as hydraulic oil.
I dont know what size container that is aviable but maybe 20liter.

jolle



Thanks jolle, I probably should try that, I have a friend who is a mechanic at a fork lift servicing shop, they probably have some. The 10-30W really does seem too light to me.

Advane sells stright 30

but I'd advise against it... multi-viscosity oils are far superior for a non-race car.

Given that new oils have a bunch less zinc, which older engines like, in a 1970 model I'd run a 15w-40 diesel oil that still has zinc or 10w-30 or 40 with STP Oil Stabilizer that contains extra zinc.
Apparently the zinc was contaminating catalytic convertors, which pre-1975 models do not have anyway.

Given that new oils have a bunch less zinc, which older engines like, in a 1970 model I'd run a 15w-40 diesel oil that still has zinc or 10w-30 or 40 with STP Oil Stabilizer that contains extra zinc.
Apparently the zinc was contaminating catalytic convertors, which pre-1975 models do not have anyway.

I've been wondering about diesel oil for my '70, but I've also been told to stay away because of the intense detergents in it.

yah i dont think diesel oil is a good idea!

Always ran 10W-30 dino oil (usually Shell or Valvoline) in my 368. Never burned any oil. Not sure if the requirments are different for the larger 425, 472, or 500.

Delvac, Delo or Rotella is a very good oil, if I still had my 425 today it would be getting 15W-40 Delvac.

Very good oils.

Before my rebuild I used 20W-50 with STP oil treatment added because the rings were so worn!!!

Now I use 10-30 or 15-30. Sometimes I throw a quart of 20W-50 in as well. You can mix them with no problem. Boy has oil gone up $$$ in the past 2 years!!!!

I read about some additive that has dissappeared from oil, I'm not up to speed on the whole thing though... I hope my new engine doesn't get ruined!

I don't ususlaly hunt for certain brands - they all have to meet API service requirements.

Hello, I was curious if anyone knew the best oil to use for my 1997 eldorado. Which oil is used normally for this year car?

Hello, I was curious if anyone knew the best oil to use for my 1997 eldorado. Which oil is used normally for this year car?

You are in the wrong section, this is for the older big blocks, here is the Northstar section:

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/

thanks for the link...

Those old engines ran very well on 30 wt except when the outside temp is regularly below 40. Switch to multi grade then.

You will hear engine struggle to start if oil is too heavy.

I don't want to burn out the bearings in the newly rebuilt 1968 DVC which does NOT have roller lifters. I'm not too concerned about the 2000 Eldorado with 103,000 miles, I'll just use 10w30 in that car nor am I concerned about the 2005 CTS, but i am concerned about my 1968 and the 1995 Fleetwood with 188,000 miles. I was using 10w30 but with its age, perhaps I might need to use 10w40 (I think the manuals say don't use this).

What ever did 10w40 oil do to earn the wrath of neearly every car mfr???

I used to use 20w50 in the 68 DVC but that was before the rebuild. I'm thinking 10w40 now. I'm certainly not going to use a 5w-anything in that car or the Fleetwood. On the other hand I don't want to have to stock 4 different oil weights in the garage - 2 coolant types is bad enough!

Someone mentioned GM engine oil supplement having the zinc additive that we need. That stuff is like molasses and should help with thickening up the oil for the old 95 Fleetwood and 68 DVC.

Does STP oil treatment have the same additives?? Either would be fine if they are both similar, but STP is available everywhere whereas the GM stuff is only available from dealers and maybe 1 shop in Tampa.

damn friggin CAFE BS :mad2:

I tend to use Rotella 5w40 synthetic. It's good for top-line diesels so it has all the good additives that the flat lifters want.

If at all possible, you should go for a 5w-- or 10w-- oil. The first number is cold weight so a lower number means better cold flow for faster lubrication on a cold start especially if you drive the Cad during cold weather.

The reason 10w40 is not reccomended on newer cars is that the engines are designed differently. Bearing clearances and design are different than they used to be and the bearings are designed to work with a 5w30 oil to take advantage of the reduced friction. Put 10w40 in there and the oil no longer flows through the system properly and will not lubricate the engine correctly.

As for using straight weight oil, leave that ancient lube for the guys with flathead Fords and oil bath aircleaners! That 30 weight oil is going to be like sludge on a cold start and be murder on the bearings. My '70 FSM states SAE 30 and 20w40 oils only to be used at temperatures above 90*F, so summer in Arizona kinda weather... If you are truly hooked on single weight, the manual lists 20W oil for weather 32*F and above, 10W for 0-32F and 5W for weather below 0F (brrr).

i use 10w-40 in my 368, last winter the temps got below 20F and my car started just fine.
i was thinking of running quaker state high mileage 10w-30, would this benefit my engine or would it be just like running 10w-30 or 10w-40??

I don't thnk you'll have problems with the engine starting regardless of what weight oil you are running, the problem is running heavier oils in winter and the engine will be started but the oil hasn't made it to all the bearings yet :eek:

10w40 will flow just as well when cold as any other 10w-- oil. That's how multigrade oils work, the first number is what weight is behaves like as 32*F and the second number is what weight it behaves like at 212*F. That's why synthetics are so great, you can get oils like 5w40 that flow great when cold, but keep their viscosity up as the temperature rises.

The high mileage oils typically contain additives that will swell the seals on your engine to stop leaks. If your engine is not leaking, or not leaking enough to bother you, then do NOT use these oils. Once the seal has been swelled up by the additives, you are pretty much 'hooked' on the oil because if you take those additives away then the seal will sometimes shrink back and then you will have a nasty leak.
If you want to change the oil from just being good ol' dino juice, then go synthetic. Synthetics in general hold up much better to high heat and extreme cold than conventional oils so your engine is better protected.

The 1995 Fleetwood manual says if its below 0F, use 5W-30. If it does not go below 0F, 10W-30 can be used. If it is always warmer than 40F, straight 30 can be used, but it has to be detergent (API SG or whatever) no non-detergent oild, or you can kiss your block goodbye. :eek:

This is right from the manual. (not the part about kissing your block goodbye though)

:stirpot:

Since its' always warmer than 30F here, and 40F or above 10 months out of the year, I might go to a higher weight...

Back in Mass, about 25 years ago, my brother put 50wt motorcycle oil in his 1970 Fleetwood 75 sedan. and then wondered why it wouldn't start in December :thepan:

The 1995 Fleetwood manual says if its below 0F, use 5W-30. If it does not go below 0F, 10W-30 can be used. If it is always warmer than 40F, straight 30 can be used, but it has to be detergent (API SG or whatever) no non-detergent oild, or you can kiss your block goodbye. :eek:

This is right from the manual. (not the part about kissing your block goodbye though)

:stirpot:

Since its' always warmer than 30F here, and 40F or above 10 months out of the year, I might go to a higher weight...

Back in Mass, about 25 years ago, my brother put 50wt motorcycle oil in his 1970 Fleetwood 75 sedan. and then wondered why it wouldn't start in December :thepan:


As of now im running 10w-30 in all my cars but im starting to think i might want to go with a thicker grade now that the warmer weather is starting up. Maybe 20w-40 or is this to thick for a v8 ? One of my friends swears by it, all i want is the best oil presure and lubractor for my motor! what do you think about 20w-40 or is there an oil close to this grade but more available? Or is it to thick for the bearings to get lubed? what do you think about this?

I ran 20w-50 in my 1968 for 7 years with no problems. Your manual will probably state 10W-40

My 1970 manual states that 10W-40 or 20W-40 can be used from 20F and warmer. or straight 30 if its above 60F.


10W-30 is also ok for 0 - 100F...