bill, knock it off. straight weight oil takes many, many, many seconds longer
to flow to all pressure oil bearings in a just started, ambient temp engine
than does multi-weight oil.

straight weight oils are proper only for engines that are started with proper
care to prelube and brought up to temperature before putting a load on it and
are run for extended periods of time before shutdown.

bill, you don't have a clew what the paragraphs above mean, so just knock it
off and don't post again on oils.

"Calif Bill"
Date: 9/18/2004 10:04 PM Eastern Daylight Time
Message-id: . net

You do not have the huge temperature differentials that cars have. Most of
the time you are in the 40-75 degree ambient temperature range.
Bill

"Dan Olstad" wrote in message
link.net...
As the season draws to a close I am thinking about fluid changes in my new
to me boat. I have 1987 Mercruiser 260s and the manual recommends
straight
30W oil. Why not a 20-40W or a 20-50W? The manual says that's ok if
straight weight is not available but it is not recommended. Can anyone
shed
any light on this for me? Thanks.-DanO