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