My brother has a 20hp Honda 4 stroke outboard. Probably 4-5 years old but no owner's manual. What type of oils go in it and what are the capacities? I'm going to look on Hondas website also.
Looks like this is the manual. Says 10w30. Would rotella t6 5w40 be good? Or some other synthetic oil? I've never had a 4 stroke outboard. I run rotella 15w40 in my boat but it's inboard/outboard.
Any marine 10w 30... some will say rotella. I had great results with RP marine products but not easy to find. probably get everything at AZ, AAP. Lower unit gear lube, plugs, seafoam, Filter too... sounds like fun motor to wrench on.