I'd go with 10/40 UNLESS it's an older motor with high hours. I've been
using 20/50 in my '68 Vette for 20 years now.... LOL.

-W

"mark s" wrote in message
m...
i've been told to use 20W50 in a 350 merc engine.
this seems heavy.

should this be used, or should i go w/ a lighter weight.