Oil Requirements For

[John O.]

I recently bought a 65 396 that is worn but fairly original. The second owner had the engine gone over in the late 1980's and had the engine set up "loose" for more power. Why anyone would want more power from a 396 is beyond me. The machine shop that did the work told him to run the engine on 15/40 weight oil to keep the oil pressure up. He lived in a small Iowa town where 15/40 was available through the local Coop. However, I now have to do an oil change and there is no 15/40 to be found. Does anyone know if 20W-50 Valvoline racing oil would work fine for this? That is the only thing I can find at many of the auto parts stores.

Thank you,
John Osterholm

[Joe L.]

Re: Oil Requirements For

John------

I'm sure that the Valvoline 20W-50 will work as well, or better, than the 15W-40. Acceptable oil to use is the least of your problems. If the engine is set up so loose that it actually needs this heavy of an oil to maintain proper oil pressure, that's the more serious problem. Engines set up with loose clearances are fine for racing purposes. However, for long-term street durability they're not so fine.

[John O.]

Re: Oil Requirements For

Joe:

Thanks for the response. I figured that it would not be good to have the engine loose. The owner who I bought the car from didn't even race. I plan on taking the engine out this fall and having it set up to the original specs.

John Osterholm

[Clem Z.]

Re: Oil Requirements For

i think 15W/40 is available from mobil 1.

[Clem Z.]

PS

if the engine run well,does not leak or burn oil i would not tear it down just because of someone statements. running 15W/40 is not the end of the world for a BBC.

[Mike McKown]

Re: Oil Requirements For

15W-40 is also available in Shell Rotella. Any Wal-Mart. It is for diesel engines but at least one Prominent member of this board says it has the proper chemical make-up to make it better suited to older design engines vs. a modern oil blended for modern gas engines.

Like Clem says, if it isn't smokin', knockin' or leakin', why worry about it?

Mike

[Craig S.]

Re: Oil Requirements For

I would much rather use the Rotella that Duke recommends than the Valvoline racing oil. The additive packages are suited for normal use, not a single day of glory with a subsequent change....Craig

[Paul L.]

Re: Oil Requirements For

You will find 15W-40 AC Delco at your local GM dealer. It is used for diesel engines (e.g. DuraMax 6.6L) as well as gasoline.

[Duke W.]

Re: Oil Requirements For

All the national brand heavy duty diesel engine oils (API service category CI-4) such as Chevron Delo, Shell Rotella, and Mobil Delvac are available in the 15W-40 grade, which is what I use, and it's suitable for temps down to about 10 degress F.

CI-4 oils in this and other grades are also available in many other brands.

Duke

[Theodore K.]

Re: Oil Requirements For

Mike,
Your response on the Rotella is interesting. I ran the 15W-40 in my Olds diesel for years and had good luck. Got 240K miles before I lost the engine. I have a '57 that has been bored to 4" and has a little taper. When I rebuilt the engine a few years ago I found this out and could not go any more so put back together. I have been using 30W oil but it does use some. I think a lot is going out the road tube as the taper is causing some blowby. Have you used the Rotella vs. 30W and found it to be less consumption?
Thanks,
Ted

[Mike McKown]

Re: Oil Requirements For

Ted:

I use the Rotella 15W/40 but only in a Power Stroke diesel and a 230 Cummins diesel. I haven't used 30W in these engines.

Many years ago, when multi-viscosity oil first came out, I, and others, noticed it would not stay in the engine as long as straight weight. I always used straight 30 detergent year round to minimize oil usage. But, that's when a new engine would use a quart of oil every 1500-2000 miles and be considered normal. Old habits die hard I guess. I use the same oil today in my old cars. Of course they don't get started up in below zero weather anymore, either.

My neighbor, a chemist, claims he did studies on multi-viscosity oils years ago and found that the oil would have the advertised higher viscosity number out of the can but after a short time in the engine, the viscosity would quickly migrate to a lesser level. That's what he said anyway.

Thicker oil will help your blow-by loss out the draft tube.

Mike

[Duke W.]

Re: Oil Requirements For

When multi-vis oils first came out in the sixties the viscosity index improvers rapidly broke down, so a 10W-30 degraded to a 10W fairly quickly. Modern VI improvers as used in current mineral oils are much more durable, and most synthetic blends don't even have any VI improvers because of their naturally greater viscosity index compared to mineral base oils.

GM no longer recommends 10W-40 oils because they have the greatest concentration of VI improvers and they are concerned about deposit formation because the VI improvers are not ashless.

GM owners' manuals from the sixties and seventies say it's okay to use straight 30W oils if you won't be doing colds starts below 40 degrees F. I still like the multivis oils eventhough it never gets much below 45 degrees in Redondo Beach, and when it gets that cold I'm usually hibernating in my 80 degree waterbed, but a low cold temperature viscosity range of a multivis will allow the oil to get to the bearings quicker on a cold start even in mild weather.

My current brand is Chevron Delo 15W-40. This is, of course, a heavy duty diesel engine oil with an API CI-4 service rating.

Duke

Duke