I have a 50HP Honda 4stroke. I noticed that there are some oils out that claim to be for 4stroke outboards and they claim many advantages to using them. Are these oils really better for marine use? Or is just a good quality oil of the prescribed viscosity what should be used. How often should it be changed if you don't have an engine clock?

Also, Should a 4stroke have carbon remover run thru it?

ttt

I don't know what Honda recommends but Merc and Yamaha use 10w-30 under 90 degrees and 10w-40 over 90 degrees. I would change it a minimum of once a season depending on hours used.

A good quality oil in the right viscosity is fine, in my opinion, never had any problems...doesn't have to say "marine" on the bottle.

As a general rule the recommended interval is 100 hours or once a year. The typical outboard in North Texas doesn't see 100 hours in a year....you said you are going by mileage...assuming an average speed of 20mph that would be about 2,000 miles.

My Honda Manuel recommends SAE 10W-30 or 10W-40 API service classification SG or SH. Change every 100 hours or six months. Mine is due. It does not say anything about marine oil. I like Castrol. It is for high revving engines.

the big problem with four strokes is they gain oil. they don't run hot enough to burn the gas out of the oil that naturally gets in it. Marine manufacturers know what their engines need for viscosity, acidity and such. use theirs.