posted 05-28-2011 01:57 PM ET (US)     

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The manual for my Yamaha 20 hp four stroke recommends 10w30 or 10w40, but does not suggest conditions for when to use each. I tend to use more viscous oils in my car since it is hot here, is this the same for boats or are there other considerations?

This will also be my first outboard oil change, so I would welcome any suggestions particular to outboard oil changes. I am already familiar with changing oil on cars.

Thanks

posted 05-28-2011 06:27 PM ET (US)            

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Outboard motors do not run that hot so 10 w 30 is fine if the manual says so. If you don't have a copy of the original manual then find one online, I am sure it will give you temp ranges for when to use each type of oil.

My Honda recommends 5 w 30 and that is what I have been running in it for the last 12 years (1999 model) and it is holding up fantastic. I have learned not to ask mechanics about this type of thing, I have have received too many bad answers. My mechanic told me 5 w 30 was way too thin for this motor, then I pointed to the sticker on the motor that says 5w 30 is preferred and he said oh I have never seen that before! You are much better off reading the manual.