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1948 Oldsmobile Engine Oil Recommendation

57j2olds

By 57j2olds
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PWN 1,000+ Points

PWN

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On recommendation from a club member, I just put some Amsoil 10W30 full synthetic diesel oil in my 22 Chandler. Apparently better rust protection and more detergents. Rebuilt motor with new babbit bearings.

 

https://www.amsoil.com/p/signature-series-max-duty-synthetic-diesel-oil-10w-30-dtt/

 

 

But I will switch to one of these oils very soon. More zinc and phosphorous

 

https://amsoil.lube-direct.com/2011/07/high-zinc-oil-amsoil/?sfw=pass1683739930

Edited by PWN (see edit history)
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Stude Light 10,000+ Points

Stude Light

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Without the oil filter go with Rusty’s recommendation and change it fairly often. Synthetic is good stuff but more expensive and the bigger issue is just cleaner oil. No need for any additives or worry about higher ZDDP in your engine - absolutely not required. Just use a good off the shelf API rated oil (probably API SN)

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Rusty_OToole 25,000+ Points

Rusty_OToole

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1 hour ago, 57j2olds said:

Thanks Rusty

 

I keep hearing everyone using diesel motor oil. 

 

I was gonna use Mobile DelVac 15w40.

 

What are your thoughts?

 

Original motor....no smoke or any burning....

If the engine is worn the thicker oil may quiet it down some. In any case you should use the thinnest oil the engine is happy with. Probably the manufacturer recommended 10 in the winter, 20 in the summer and 30 in very hot weather. But back then, they did not have the advantage of multigrade oils. 10W30 was made to replace all three, with the advantage of quick circulation and full lubrication when cold, and not thinning out or breaking down when hot.

 

Many owners of older cars make the mistake of using straight 30 or other heavy oil on the recommendation of Goober down at the filling station. This is wrong. Most wear occurs when first starting the engine, before the oil begins to circulate and before the engine warms up. The manufacturer recognized this and recommended lighter oil except in very hot weather, and as soon as detergent oil and  multigrade oils became available, that is what they called for.

 

Detergent oil came out around 1947 and multigrade oils in 1951. 10W30 was  the default choice of every garage and dealership from the fifties thru the eighties. Today they have even lighter oils but they are for the newer cars.

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Stude Light 10,000+ Points

Stude Light

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23 minutes ago, 57j2olds said:

Keep reading about Rotella and Delvac..

 

Heck I dunno.

 

 

Either one is fine too, they just cost more. Any fully synthetic will work too. All depends on what you want to spend as you will find no performance difference in your application. Just make sure you do frequent oil changes.

 

Lots of folks like Rotella or VR1 for the higher zinc and phosphorus content required for high revving, high performance engines with flat tappet camshafts and I would agree that would be a good choice for a race engine but for those us that don’t race, modern oils are fine. The entire ZDDP “hoax” has been created by the people selling the stuff and perpetuated by those that haven’t read all the SAE papers and test reports on why the current levels are fine except in the most severe cases. Lots of anecdotal stories out there and way too much discussion on oils….I wonder why I bother anymore. I don’t mean to belittle your question though. We are just trying to be helpful. Again, those oils are fine choices too. I choose to save my money.

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Rusty_OToole 25,000+ Points

Rusty_OToole

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Zinc was first added to motor oil AFTER the first OHV V8s came out in the late forties - early fifties. Some of the first ones suffered from cam and lifter wear because they were more heavily loaded than the old flatheads and low revving OHV sixes. Your Olds is one of the old flatheads that did not need it.

 

In recent years they took the zinc out because today's OHC cars and cars with roller lifters don't need it. The old fashioned flat tappet pushrod engine is a thing of the past.

 

The only cars that need it, are high performance V8s with flat tappet cams and diesels which have problems of their own.

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Rusty_OToole 25,000+ Points

Rusty_OToole

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Because you have no oil filter it is a good idea to change oil frequently. You do not need extreme heavy duty or synthetic oil. Your engine is not that highly stressed. So use the cheap oil and change it every 2000 miles. Oftener in dusty conditions. Any good name brand will do, such as Shell, Esso, Valvoline, etc. If it says on the label "for older or high mile engines" that may be all to the good. I suggest 10W30 but if the oil pressure drops too low when it is hot or gets noisy you could try 15W40. But thick oil will not cure a worn out motor.

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Stude Light 10,000+ Points

Stude Light

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1 hour ago, Rusty_OToole said:

n recent years they took the zinc out because today's OHC cars and cars with roller lifters don't need it.

Just a correction- they reduced (did not remove) zinc and phosphorus levels as they contaminate the catalytic converters. There was a lot of testing that SAE did to ensure backward compatibility to older engines to strike a balance between catalytic converter problems and flat tappet engine problems. The current levels were shown to be adequate in performance production engines but most people that run those or build them beyond specs use the specialty oils with the higher levels of zinc and phosphorus that were previously specified. I would also run the special oils in those engines as added protection.

 

Additionally, going beyond those levels causes oxidation and spalling so, too much is bad also.

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Oldtech 10,000+ Points

Oldtech

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As RustyOtoole stated. Flatheads do not need hi pressure oil. They have lobes that lift x say.375, and the valve moves.375.  The kettering engines - Olds, Cad, Stude. had rockers that multiplied the lift of the valve, so a lobe of say, .25 opened the valve .4.  Great for performance, but greatly increased the pressure on the lobe and lifter.  Many of the oils of the day couldn't handle it. Good oil was available, but so was cheap stuff, and many people were accustomed to using it.  I remember when I was a teenager and early 50's Olds v8's were common, that they almost all had valve noise.  At least, that's my memory. 😁

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Ben Bruce aka First Born 25,000+ Points

Ben Bruce aka First Born

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41 minutes ago, Rusty Heaps said:

You should be able to find one of these filters for a $20 or a little more. It won’t look this nice for that money, but will clean up easily.

4206A49F-F51F-4FAF-9189-C1D0BA6FDA42.jpeg

 

  1953 Buick there.

  I have one of those .   Mount is special made to mout to the thermostat housing. One could find/make a mount. 

 

  $25.00 plus the ride if you want it

 

  Rusty and Stude are right on on the oil.  Personally, I use store brand.  I [you?] will never drive enough miles for the engine to know the difference.

 

  Ben

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