"blueman" wrote
The auto-techs said all the new automotive oils have detergents for
regulatory/standards reasons. But that plain (non-synthetic) 30 weight
is still made also without detergents for older engines.

Perhaps they are wrong or perhaps you can get synthetic 30 weight
without detergent in a compressor parts store... But I would be
interested if anybody has found a source of synthetic 30 weight oil
without detergent.


I'd go to an industrial supply house or www.mcmaster.com for compressor oil.
They make a synthetic that is probably the same 30 weight with no
detergents. Mc Master No. 1411K31 for 30 weight. $53 a gallon. Lifetime
supply for most of us that use a compressor lightly.