"Gene Kearns" wrote
Marine grade oils are formulated for a damp environment. Not a bad
idea.

Using a straight weight oil in warm climates is probably preferable to
a multi viscosity oil. If you don't need cold weather starting
formulation, why give up superior EP lubricity?

Before you feel the need to give the dry start lecture, consider that
the first number in a multi-viscosity oil has nothing to do with
viscosity. If it did, there wouldn't be any 0W-40 oils... which there
are.

IMHO, synthetics are preferable.

Modern engines are built with such tight tolerances, using a thick oil
probably does more harm than good.

I'd use multiweights on any reasonably modern water cooled gasoline engine.
Have not yet become a user of synthetics. Tend to change oil more by date
than hours. Twice a year for cars and boats. Believe strongly in changing
oil filters with each oil change and sometimes wonder if more often might be
better.

Starts, condensation, and poor oil circulation are probably greater concern
than viscosity breakdown for marine engines.

360,000 km so far on Chev Blazer V6, too soon to conclude about old 165 Merc
I/O.

Used to put 50W into old British motorcycles, but they never ran enough to
test longevity.

surfnturf

surfnturf