Packard Forum Index » Pre-War (1899-1942)

Before my mechanic dropped the oil pan and cleaned it he recommended non-detergent 30 weight oil. After the cleaning he put in 10W30 but said I could also use 30 weight detergent oil. Any thoughts on this for a summer only driven car?

I have had a number of 1929 model Packards and Cadillacs over 50 years and only ever used a straight 20W50 multi grade oil. I consider a 10W30 a too light in an old engine.

Respectfully, Club Sedan, that molasses is too thick, accomplishes naught. Some people take a more is better approach to everything, which does your engine, your car, no favor.
Some even use diesel oil, despite Chevron, ExxonMobil, ConocoPhillips petroleum engineers and techs, themselves owning collector cars, explaining that oil formulated for gasoline engines is better for gasoline engines, without resorting to a dissertation here.

Nearly all automobiles into the 1930s and '40s called for 20W in the winter, 30 summer. Just check any old MoToR Auto Repair Manual, make/section by section. Don't reinvent the wheel.

Half a century for me, too, and those first years, also so believed 20W/50 must protect better. It doesn't. If you're flogging an old "muscle car" with worn rings and guides, but otherwise, no.

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Why? We're dealing with the same bearing clearances.

Just took apart my lawnmower engine and found a 1.8 thou diametral clearance on the rod bearing. 10W30 all day on that.

I could see running 10W40 in an engine with moderate mileage. But really thick oil will end up with lesser oil flow at the same oil pressure.

I bought 15W40 for my 55 320 engine where I measured all the bearings to be at the edge of the recommended value (2.5 thou).

At the risk of piling on, running to viscous an oil can actually be bad, with inadequate flow at start up. Although this is less an issue in flatheads

That is you opinion, it works well in my climate and has done so for 50 years on a number of cars. 20W50 is a higher viscosity and covers a broader range of conditions such as higher speeds and temperatures and adverse conditions.

Not saying it doesn’t work, just that « more is better » is not the way to go. My opinion is based on manufacturing oil additives, and has to do with the cold viscosity and initial oil circulation on start-up

So much drama here about oil. First off, if your engine does not have an oil filter you should use non-detergent motor oil. Detergent motor oil does not have actual detergents (soap) in it, but dispersants which keep the byproducts of combustion in suspension to be carried to the oil filter where they are removed.
Understanding the viscosity index of the oil tells us that a 10w-30 oil has the viscosity (flowability) of a straight 10w oil at LOW temperature, and the lubricating properties of a 30W at operating temperature. A 20w-50 motor oil, at low temp flows like a 20w, and yet has the lubrication properties of a 50w. Without getting into "centistokes", etc. the key word is PROPERTIES of a 50w, NOT actual viscosity (thickness).
As mentioned above, the manufacturers recommended straight 20 for cold weather and straight 30 for summer weather, while some manufacturers recommended 10w for Alaska duty.
Another mis-understood theory is that you NEED HIGH ZINC oil. Those of us in the antique automobile hobby are NOT running high pressure chrome moly valve springs on big cams and 5-6k rpm engines. We're lucky to see 3K rpm.
Any of today's name brand engine oils are 100x better than the oils of the 30's, 40's, and 50's.
In 1973 I bought and restored a 1938 Buick, that I still own, and bought my first Packard in 1975, and now 50 some years later and several Packards later, and overhauling the engines, I have ONLY used Shell Rotella straight 30 or 15w-40 and still do.
At the end of the day, we have our own opinions and we do what we think is best. 20W-50 will not hurt your engine. PB