I've read some threads debating what oil is suitable for larger 4-stroke outboards, but didn't see much for smaller engines. I recently purchased a like-new 2010 Yamaha 4HP. Peering at the oil it must have been changed before storage as it is perfectly clean. In fact, everything under the cover looks as clean as a new outboard. In any case, the manual specifies the following:
Recommended engine oil group 1*:
SAE 10W-30/10W-40/5W-30
API SE/SF/SG/SH/SJ/SL
Recommended engine oil group 2*:
SAE 15W-40/20W-40/20W-50
API SH/SJ/SL
It says to go for group 1 first, but if you can't obtain go for group 2. This chart seems to imply almost any automotive oil would satisfy group 1. For general protection reasons I'd like to use a full synthetic oil. But, I'd rather not pay boutique oil prices at the marine store for something labeled "marine" that might not be as good as standard automotive stuff. This thing will power a small dinghy and mostly see short runs of 15 minutes or less during the summer, so ease of pull starting is a factor more than hot running at WOT. Thoughts?
Recommended engine oil group 1*:
SAE 10W-30/10W-40/5W-30
API SE/SF/SG/SH/SJ/SL
Recommended engine oil group 2*:
SAE 15W-40/20W-40/20W-50
API SH/SJ/SL
It says to go for group 1 first, but if you can't obtain go for group 2. This chart seems to imply almost any automotive oil would satisfy group 1. For general protection reasons I'd like to use a full synthetic oil. But, I'd rather not pay boutique oil prices at the marine store for something labeled "marine" that might not be as good as standard automotive stuff. This thing will power a small dinghy and mostly see short runs of 15 minutes or less during the summer, so ease of pull starting is a factor more than hot running at WOT. Thoughts?