Re: Oil for Yamaha 115 hp 4 stroke
I have to agree with JB, plan old dinosaur oil until its through the break in period. If you put less than 200 hours a year on it I would stick it dino oil since you need to change it once a year anyways. I've seen what happens to an engine thats broke in on synthetic, my buddy built a $$$$$ engine for his car 7 years ago and put the "best" oil possible in so he wouldn't hurt his investment. At 2000 miles the rings still didn't seat and we ended up pulling the engine, honeing the cylinders, and installing new rings. Rings were fully seated in only 50 mile using regular cheap mobil oil. He switched to synthetic at 2000 miles and its been great since and it made 20hp more on the chassis dyno at 2000 miles with the rings seated properly.