Gear Oil vs Lower Unit Oil

76Red18 · #1 12-09-2007, 02:44 PM

Changing water pump and oil in my 99 Johnson 150. Is it ok to use castrol 80-90 hypoid gear oil? I have a 5 gal. bucket full. Thanks in advance for your comments.........Richard

JohnB · #2 12-09-2007, 04:08 PM

My first choice would be Amsoil synthetic marine, and my second choice would be prem. Merc lower unit oil. The additives in these will mantain lubrication and corrosion resistance if water gets inside. Straight gear oil is ok as long as water doesn't get inside.

76Red18 · #3 12-09-2007, 04:56 PM

Never know when you'll get intrusion, so AMS it shall be! Looks like a good product, got some on order, costs only a buck and a half more per quart than the penzoil I've used previously. Whats your thoughts on the pre-mix 100 to 1? I use Johnson/Evinrude red type @ 50 to 1 with very little smoke and carbon build up; I think the carbon gaurd additive I use keeps the build up in check. I just wonder about that high ratio....Richard

gss036 · #4 12-21-2007, 10:16 PM

Just my personal opinion, but I would stick w/50-1 mix. I run Penziol Prem synthetic blend in my 200 hp Merc.