Lower unit oil.
 

Quick silver 80/90 weight lower unit oil or 90 weight lower unit oil,witch is better?

I like the Merc High Performance. But not sure why, just always used it.

Phat, I used pennzoil,and Mercury / quick silver lower unit oil and could not see any change,the reason I asked is I ordered it from Amazon and the 80/90 weight is less expensive and was just wondering why. My engine is a 1988 year so I don't think it would matter,I'm sure the oil came a long way from 1988 .

The guy that worked on my outboards for the last 30 years used to race offshore boats. He said the merc oil is better at maintaining its viscosity when introduced to water.

Have no other knowledge or proof of this, but he said it and I believe him. I only use a quart a year, so why not go top self.

Maybe spare or ferm can offfer an opinion