lower unit lube question

[homerj]

I just purchased what I thought was lower unit lube. When I look at it more closely it doesn't specifically state is is for lower unit or marine use. It is Pennzoil gearplus SAE 80W-90 GL-5 multi-purpose gear lubricant. Does anyone know if this will be okay to use, or if I'm better off buying a type that says lower unit lube?

Thanks.

[Gus]

I think you should find one specifically use in lower units. The main difference I believe, is a lube made specifically for lower units will mix with water should you be unfortunate enough to have a leak. This way you have a higher level of protection in case of a leak.

When I had a leak, my lube came out somewhat runny and gray. It was mixed, not separated like normal oil/water. Replaced the seals and I was good to go after that. No damage that amounted to any need for other repairs yet.

Gus

[homerj]

Gus, thanks for the info. I never thought about the oil/water not mixing.

I'm on my way out the door to exchange for the real stuff.

[Jeremy airjer W]

If its run with water in it, its going to be milky no matter what kind of lube you use!

[Gus]

This is true, but I wonder if it will still be suspended after two or weeks of sitting? All I can do is speak for myself and it was still gray, not seperated. If I have some time I might dig a little more research but my former searches and grand pappy's words (he was also a mechanic by trade like airjer) tell me to get the marine stuff.

[MercMan]

What size motor is it? If it's high horsepower, then definitely don't use it. Real lower unit gear lube has additives in it specifically for lower unit operation. Lower units are submersed in sometimes very cold water, then when under power the gears and shafts inside get very warm. When you stop, they cool down rapidly. Real lower unit gear lube is designed to work well under these conditions. 80-90 GL5 is used in ATV gearcases and car gearcases. The temperature changes aren't as drastic or quick in cars and ATVs. In the winter, it takes a while for your truck to get going due to the "thick" oil in the engine and in the drive system. My advice is to put that Pennzoil on the shelf and go to the store and get the good stuff. As with anything else, it pays to do it right.

[New Yankee]

Gus and Airjer, I was told that the marine grade lube had/has emulsifiers that will keep (or try to) the H20 suspended and reduce the chance of water settling in the foot (gears) of the lower unit. That is the primary difference between the two(?)

[Surface Tension]

I believe the gear oil for outboards is formulated for the high RPM the gears turn at. Normal gear oil would froth up and blow the seals out.

[PierBridge]

Quote:

---

What size motor is it? If it's high horsepower, then definitely don't use it.

---

First if it's not a electric shift probably yes if a lower HP engine, but if it was mine I would spring for a good syn. gearlube.

Good Luck

[Jeremy airjer W]

This is great stuff. Who knew?

It makes sense to keep it emulsified. Water by itself is not a good lubricant, abviously. keeping it suspended would allow for maximum lubrication in an undesireable condition.

I never thought about heating and cooling. makes good sense if you think about it.

Personally, as New Yankee knows , my lower unit only holds a couple tubes worth of lube so its not a huge expense. Why not spring for the stuff that is supposed to be in it.

Hey Gus, Automotive "Technician".

[Gus]

Airjer, I'll make sure to get it right next time!

Everyone have a great weekend. Should be a nice one out. Roofing for me on Saturday, Sunday I might get my ice gear out to play with!

Gus