Re: changing engine oil
I have converted my Yamaha 4 stroke to 10-40 synthetic oil. I am long out of warranty and love the thought of synthetic in my motors. On my KeyWest we picked up 200 rpm wot after the change. What is important to realize is that once using synthetic, you should not go back....
On both those motors, you should be able to tilt them full up, remove the oil drain plug and slowly lower them. I use a funnel with a hose attached and drain into a 5 gal bucket. I do one motor, than the other. By the time I come back to the first one, the filter comes out with no oil spill...
You must be careful and not overtighten the drain plug. The squish washer will flatten and you can leak oil. Don't know the torque specs, but on mine, I bought new plugs and torque as required.
Pretty simple and straightforward. And if you use Amsoil, you will read good things about using synthetic oils in marine 4 strokes. I, however use Castrol Syntec...just match the viscosity rating your motor calls for..also, I use synthetic in my lower units....good luck!
