Lower unit gear oil

[etripp111]

Hello

I have a late 70's or early 80's Mariner 85HP outboard. I need to replace the lower unit gear oil. I have some 80W-90 gear oil that I use for my kid's mini bike clutch, as well as the transfer case in my manual transmission 4x4.

Is this the same as the "marine lower unit gear lube"? They both have the same viscosity and are both GL-5........

Thanks

Tripp

PS I know that synthetic would be best....maybe next year....

 

[jeffdjpeat]

Re: Lower unit gear oil

personally i always try to buy the exact stuff needed, but later on i think, " you know, theres some idiot doing something 10 times dumber then me, and still putting along!" Keeps my spirits up. but the kids dirt bike oil may not be suitable for underwater use? im not sure, but i would buy the right stuff, considering the small cost, and major repair if it is the wrong stuff.

 

[kenmyfam]

Re: Lower unit gear oil

Personally I would use the correct oil. It is said to have emulsifiers that help to keep some viscosity if water should get in.
Possible expensive way to save a few $

 

[etripp111]

Re: Lower unit gear oil

OK. So what IS the correct stuff?

Tripp

 

[pwfish1]

Re: Lower unit gear oil

the correct stuff will be the 90 wt gear oil with the Mercruiser name on it for $10.99

it will be right next to the sta-lube 90 wt gearoil for $3.99.

for years i bought the name, until one summer i only had 3.99.

stil paying 3.99.

 

[etripp111]

Re: Lower unit gear oil

OK. Sounds like a mixed message.......

I'll just use the stuff I have. I cannot find ANY information that states the "marine" stuff is any different. There are no additives for "water proofing" the oil that I can find...............


Tripp

 

[emckelvy]

Re: Lower unit gear oil

Tripp, regular old automotive tranny gear oil will lubricate your gears just fine. But Marine-Grade, "Hi-Vis" gear oil also has additives which will keep any water which finds its way into the lower unit, well-mixed with the oil. This will help keep the bearings and gears from corroding away.

Ordinary oil will allow the water to 'settle' and, if you're running in salt water, you've then got a layer of highly-corrosive water sitting on your bearings/gears. An oil-water mix surely isn't good for things either, but isn't nearly as corrosive as a straight shot of water.

So, you're not gonna kill your lower unit by using tranny oil. But you should also make a point of regularly checking the oil quality by pulling the lower (oil drain) plug, to make sure the oil's staying clean.

If your lower unit's seals are in great shape you shouldn't have to worry about water intrusion anyway.

I use Sta-Lube Hi-Vis marine grade oil in my lower unit. This is available "in season" at Wal-Mart for a little over $4.00/qt. Pick up a hand pump which screws into the bottle and it'll be a lot easier getting that oil in.

Note that higher-horsepower, or high-performance motors (big V6's) will probably specifiy a higher-grade of oil due to the stresses imposed on the gears/bearings, but your motor will do just fine on the regular stuff.

HTH..........ed