Lower unit oil question

[Tim Murphy]

Dear Board,

I have several small outboards that I need to winterize. As part of the process I am going to drain and refill the lower unit gearcases. The outboards I own are a 1982 Evinrude 35 HP, a 1986 Evinrude 6 HP and a 1997 Yamaha 4 HP. I bought all of these motors this year in running condition and like to keep them in that condition for a long time.

Between the 3 motors they will need between a pint and quart of gear oil. The gear oil at a boat dealer is $ 8.00 or $9.00 a pint. I can buy a gallon of 75-90WT gear oil for limited slip automotive rear ends for about $ 13.00 at Pep Boys. That will be enough oil to last me for for several seasons.

My question is this, will I do any damage by running the automotive oil in an outboard gearcase? I'm thinking I won't but before I try to save a couple of bucks I'd like to hear a confirmation from someone? If it's a bad idea please don't be afraid to tell me that.

Regards,

Tim Murphy

 

[Frank Acampora]

Re: Lower unit oil question

You wion't hurt them. However, the outboard specific oil has more emulsifiers and corrosion inhibitors. SO: If you don't get water in the lower unit, or you check and change it regularly, it doesn't matter. If you do get water, the outboard specific oil will provide more protection.

I know a few guys who use regular rear-end oil in their outboards and they claim there is no difference.

A few years back, Wal-Mart had a close-out on synthetic outboard lower unit oil. At a buck a quart, I bought all twenty that they had on the shelf. Now I am out and just may go to rear-end oil.

You do realize that we may well have started a debate like the TCW-3, 100 to 1, ethanol in gas. Everyone will have a pro or violently con opinion! LOL

You DO need to check the manual though: Some engines (like OMC Selectric Shift) require a different oil.

 

[Texasmark]

Re: Lower unit oil question

You wion't hurt them. However, the outboard specific oil has more emulsifiers and corrosion inhibitors. SO: If you don't get water in the lower unit, or you check and change it regularly, it doesn't matter. If you do get water, the outboard specific oil will provide more protection.

I know a few guys who use regular rear-end oil in their outboards and they claim there is no difference.

A few years back, Wal-Mart had a close-out on synthetic outboard lower unit oil. At a buck a quart, I bought all twenty that they had on the shelf. Now I am out and just may go to rear-end oil.

You do realize that we may well have started a debate like the TCW-3, 100 to 1, ethanol in gas. Everyone will have a pro or violently con opinion! LOL

You DO need to check the manual though: Some engines (like OMC Selectric Shift) require a different oil.

I agree. If it doesn't leak why do you need the special additives? Buttttt Frank, for the price and peace of mind my choice is the LU oil.

Mark

 

[Chris1956]

Re: Lower unit oil question

Gee, There are lots of aftermarket Marine gear lube. Wallyworld carries some. They are about $5 a qt. You likely need 2 qts/ year. Spend the $10 and move on....

 

[robert graham]

Re: Lower unit oil question

Walmart sells a fairly inexpensive Marine Specific Outboard Lower Unit Oil...so for just saving a couple of bucks$$, why not use the specified stuff?....just in case some water sneaks past one of those lower unit seals...

 

[mrmamiller]

Re: Lower unit oil question

I ran into trouble finding marine specific lower unit oil near where I live. Walmart SuperStore is more concerned about selling groceries than keeping marine oil on the shelves. NO marine gear lube at my Wally World.

 

[robert graham]

Re: Lower unit oil question

Try Autozone, Advanced Auto, NAPA, etc....the Marine Lower Unit Oil is usually not hard to find. Wally World probably carries it at stores near lakes, rivers, boats?....I drain my lower unit every year and the oil always looks clean and clear like when it went in, so I thin it with some Kerosene and run it in for my chain saw chain lubricant...heck, no need just to pitch it out!

 

[Home Cookin']

Re: Lower unit oil question

the real problem $ wise is that the motors need an amount that doesn't match the bottles: 34 oz, 18 oz, etc. So unless you buy about 8 bottles you don't come out even (8 hot dog buns, 10 hot dogs). And call me supersticious but I'd rather not mix brands.

Seems to me, especially if you are changing frequently, that as long as the old oil is not milky and you don't use the bottom with the steel filings, a couple ounces of the old mixed in to round things off can't hurt.

 

[MH Hawker]

Re: Lower unit oil question

Not to muddy things up, but I have been told that marine grade gear oil is non foaming in use, so its a lot better to use that. But any brand of marine oil is fine. With the exception of the older OMC with electric shift LU.

 

[Tim Murphy]

Re: Lower unit oil question

Dear board,

I finally found a Wal-Mart that had 80-90 weight Marine gear oil on the shelf so I bought enough to take care of things for now.

In reading the owners manual for the my 1997 Yamaha they spec 90 weight hypoid gear oil which is straight old fashioned gear oil that has been used in all kinds of gear boxes for a century or more so I'm sure the automotive gear oil would be fine in the Yamaha. Since the Evinrudes are even older than the Yamaha, I suspect the automotive oil would be fine in those motors as well.

I think the type of a gear oil is more critical in I/O's than it is in outboards since the I/O's have various types of internal clutch packs and the outboards are just a set of gears.

The work is in progress and everything should be completed and stored before the big storm hits, that was my main concern.

Regards,

Tim Murphy

 

[Bamaman1]

Re: Lower unit oil question

I started to buy 2 quarts of Mercury Lower Unit grease @ $10 at Walmart last week--in the Automotive section. I walked past the Sporting Goods department and found their wall of marine parts, including $5 Pennzoil lower unit grease 75W-90.

I put the Merc grease back and bought the Pennzoil. It'll do fine in a Yamaha--despite their spec.ing 90W oil. And, I only used 1 quart, in spite of their specs saying 33 ounces. Had I not used the pump style fitting, I'd had to use 2 quarts squeezing the 32 oz. bottle.

I would stick with marine gear grease specifically, even if it's Walmart's house brand of grease. I've been using their outboard motor oil for 25 years, and my 2 stroke engines are spotless inside.