Can I use regular gear lube in my lower unit?

[SteveD2]

*HOPEFULLY* I will have my boat running by Tuesday and will take it out for a ride then. The Amsoil LU oil that I ordered will not be here before then. Will it be ok to use standard 80w90 GL5 gear oil in the lower unit for a trip or two?
(motor is a '74 Mercury inline 6)

 

[joee12]

ZMOZ, I have used the Schaeffer's 267 and Mobil HD 80W90 oils in my lower unit. A tech from Evinrude/Bombardier told me that as long as it is GL5 rated, it is OK to use. I would use it, and then put in the Amsoil when you get it, Joe

 

[darrenc]

Yes. You may. There is no magic to lower unit lube. I’ve used the OMC, Amsoil, and Schaeffer 267 gear lube on my Volvo Penta. As long as they meet the spec, you are fine. Mine calls for 75 or 85W-90 GL5, synthetic preferred lube.

 

[Hasbeen]

Any TOP QUALITY gear lube will be fine. Pass on the low end lubes such as you find in gallons in parts stores. Reason being that they may not have the anti foaming agents needed in a lower unit. Lower units have very little extra oil and space for expansion, Therefore if the oil foams too much you will loose your lubrication. Good choice though on the Amsoil.

 

[Bio-T]

Pennzoil Marine Synthetic for an OTC is a top oil and rated GL-5. My number one recommendation is pass on the Lubrimatic gear lube. It turns black quickly and smells terrible. Also the bottle lists it as synthetic, but the web site clearly showed it was semi-syn.

 

[QuadDriver]

wellllllll, the anti-wear additives that make a gl5 a gl5 are corrosive to 'white metal', which your lower unit is full of...gl4 is typically the requirement for lower units.

 

[SteveD2]

quote:

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Originally posted by QuadDriver:
wellllllll, the anti-wear additives that make a gl5 a gl5 are corrosive to 'white metal', which your lower unit is full of...gl4 is typically the requirement for lower units.

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All the lower unit lube I've ever seen says GL5 right on the bottle.

 

[blano]

I havent seen any whote metal in the lower units I Have been in.

 

[Drstressor]

Anything that isn't made of hard steel (bushing for example) are considered white or soft metal. GL-5 lubes have about twice the level of ZDDP, etc. than GL-4. High levels of anti-wear compounds can attack soft metals and accelerate corrosion. Most GL-5 lubes are now tested for soft metal compatibility. If I remember correctly, the designation MT-1 means that the GL-5 lube SHOULD be OK where a GL-4 lube is specified. It would probably be best to use a GL-4 lube if that is what you manual says to do. Amsoil sells a GL-4 lube for older lower units.

That being said, a couple of runs with a GL-5 lube shouldn't hurt anything. Any potential damage would take place over several months at least.

 

[Geoff]

Actually I have always heard that GL-5 is not good for yellow metals, like copper, bronze. GL-4 better for those. If anyone knows for certain please post.

 

[darrenc]

Volvo Penta specs GL-5 for their lower units.

 

[Scali62]

I'm not sure but I believe that only " marine gear lube " should be used in OB's & IO lower units & this is why..
I researched to heck out of this question after adding Mobil 1 gear oil { non marine } to my 40 hp Merc today ..
I read on Iboats boating forum where it's stated in a thread about this issue by someone in the Marine lube industry that " emulisifiers "{s} are added to marine gear lube to promote the blending with water so the lube still is effective
when & if a leaky seal occurs & without this additive the water would stay on the bottom of the lower unit causing catastrophic lower unit damage.
I tell you what, dont know if thats true but I've had milky lower unit oil before & leaky seals that need replaced & not the whole LU, I wonder if theres any truth to this..
I think tommorow, I'm heading to boatersworld for some Merc gear oil just to be on the safe side..
Any thoughts..?
First post in a while but still a lurker, great site

 

[Schmoe]

I think regardless that the oil and water is going to mix when operating. When sitting, the water will settle to the bottom, no matter what type of oil you use. Depending on how much water is in the drive, it will start to oxidize on the internals. I think your always going to get a little bit of moisture in with the lube. It's just the nature of these things. It will either come from condensation or a slight leak. I mean, anytime you have an engine part in the water, somehow it's going to find it's way into the mechanisms. Just watch when you drain. There is probably a tablespoon or so that will drain off then the lube. If you got more than that, then you got problems somewhere in the outdrive and will need fixing. No amount of emulsifiers will keep your internals from rusting.

 

[Scali62]

Yeah, Schmoe I think your may be right, I continued to read about this & it seems most people believe as long as it's GL 5 rated then it's fine also some anti foaming additive is needed which the mobil 1 synthetic I added has..
Was out this morning on the boat came back early { too windy for my 13 ' Whaler } & checked the lube, looked perfect..
I'm concerened with this because I " may " have a slight seal leak as my lube looked slightly murky but not real milky yesterday when I changed it but..
I think it's good to go.. thanks for the comeback

[ September 14, 2004, 12:45 PM: Message edited by: Scali62 ]

 

[FowVay]

FWIW, I spoke to a person at Pennzoil about using a marine lower unit oil in my cars transmission. The explanation about the difference between normal automotive GL5 gear oil and the marine gear oil was the same as was mentioned above. The marine oil has different additives to prevent corrosion and also to help with water separation.

So this makes two places that I've heard this explanation. Pennzoil said that the marine gear oil would work fine in my cars transmission provided that it required a GL5 lube. The only reason that I considered it was that it was on clearance at Wally Mart for $.50 per quart.

 

[Scali62]

I drained the auto gear lube from my LU & added marine stuff after speaking to a guy who's a marine mechanic that concurred the fact that the marine stuff does have special additives that promotes the blending of water ..
He told me if your seals begin to leak with the auto lube in there the LU will blow much quicker due to absence of these additives.
My concern is I have a slight seal leak & I dont want to lay up the boat now that the fall run is starting here off Long Island so I've been changing out the lube every few trips & replacing with cheap Lubrimatic marine lube to be on the safe side till I get to the seals this winter..
Fowvay, 50 cents a quart wow ! Look @ it this way, if your tranny some how gets water in there now your protected