At one time I asked Bill Grannis if he had a recommendation on which oil I
should use in my new Yamaha 4 stroke. He responded with information on
TC-W3 approved oils which are used in a 2-stroke. He quickly realized the
confusion and provided another answer applicable to four stroke engines.
Please note that neither Bill nor I recommended using a TC-W3 oil in a four
stroke engine.

Here is part of his most informative answer:

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On 4-stroke oils, there is a fairly new certification system endorsed by
the
oil blenders and the 4-stroke manufacturers, called "four-stroke,
water-cooled" or FC-W. Because an outboard may run in sal****er, sit unused
for long periods of time, and runs high rpms for hours on end unlike a car
motor, the industry wanted a spec for approved outboard oils. New owners
manuals now state what oil grades to use and say an FC-W certified oil if
you don't use an OEM lubricant. If you are into synthetics, surprisingly
the
Amsoil 4-stroke oil is FC-W approved unlike their 2-stroke oils which are
not TC-W3 approved. Here is more info on the FC-W lubes:

http://nmma.org/certification/programs/oils/fc-w.asp
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The link provides some alternatives for those buying oil for four stroke
marine engines.

Thanks again to Bill Grannis!
--
John *H*