Lower Unit Gear Oil ???

HookedOnReds

Cadet
Joined
Oct 1, 2010
Messages
7
Can modern 75w140 synthetic gear oil be used in my 1980 Evinrude 115hp Lower unit? I ask this because I happen to have about 8 qts of this gear oil.
 

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: Lower Unit Gear Oil ???

My guess would be yes, and if I had it I'd use it, but will defer to someone with that vintage of engine. It's too new for me.
 

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,690
Re: Lower Unit Gear Oil ???

If it is not an outboard engine gear oil it won't contain the additional corrosion inhibitors to guard against the effects of water ingress.
If it is just, as I suspect, an automotive oil, then the objections to using it on this basis are just as valid as the objections to using automotive sae 80/90 oil.
 

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: Lower Unit Gear Oil ???

Agree, you will save $5 using the oil you have but may cost yourself a lower, it just isn't worth it.

Lower oil has stuff in it that auto oils don't because the engine operates in a completely different environment.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Lower Unit Gear Oil ???

Marine oil is a special hypoid oil, which will mix with a small amount of water and still maintain it's lubricating properties. Automotive oils won't do that.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Lower Unit Gear Oil ???

Something to ponder!! GL5 is GL5 whether it is marine or auto. Water is a darned poor lubricant. Marine GL5 "supposedly" has "more" emulisifiers in it which allows water to mix with the lube should you have a leaky gear case. Since water doesn't lubricate well, why mix it with the lube that does. So either way, the gear case will not live long if not repaired. I've used auto GL5 (because I had it on the shelf) and because I did does not mean you "should". But my feeling is that in a properly sealed gear case, either will work just fine. Marine GL5 is yet another way to extract another buck or two from your wallet.
 
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