Gearcase Oil

[Rob J]

I have a 1993 4hp. I also have 2 cases of 80-90 wt. motorcycle gear oil. Is there a difference between "marine' gear oil and other gear oil? Wondering what weight "marine' gear oil is?
thanks,
Rob j

 

[Boobie]

Use only a marine grade oil no matter where you buy it from. 80-90 wt

 

[haffiman37]

On that engine, would have used the motorcycle oil as long as it has the same general lubricating spec. Main difference with outboard gear oil is its ability to handle water in the oil. Just check/change a bit more frequently.

 

[hystat]

I use regular 80W90 in all my outboards - never had a problem with foaming or anything else.

 

[andrew04]

Use motorcycle oil, marine oil does not have additives that help it blend with water, as such additives do not exist. Verify seal by putting about 8psi of air in lower unit and using soapy water to identify leaks. Replace seals as necessary. Good luck!

Two types of people have marine oil in their gear cases, those with brand new or warranted engines, and suckers.

 

[SuperT]

It's your motor, do what you want. I only use marine oil. Right or wrong, no one on here will have to shell out the money if something fails. Just you.