Lower unit lube

[Jon - CLou]

What's your favorite brand of lube for lubing your outboard lower end unit?

Currently I'm using Mercury high performance lube, but I would like to know if there's better.

Thanks, Jon

[Notayot]

I'm using the same lube, the bluish colored fluid. I've had good luck with it, and the Merc dealer where I buy it in PA says it is great at keeping water damage to a minimum if you do have a seal failure. I change it twice a year.

[thataway]

I suspect that all of the "Branded" lubes are made for the specific engine manufactuer by one of the oil companies. I have generally used either the engine specific lube or Pennzoil brand lower unit lube. Pennzoil has a variety of lower unit oils. There is the GL4 Ourboard Gear Lube, the High Viscosity Lower Unit Gear Lube (GL 5 & 90 Hypoid oil spec) and Pennzoil 100% synthetic Lower Unit gear lube. Some of the older lower units used ATF.

Currently I am using the Suzuki brand, since the engine is under warantee for 6 years--I prefer to document that I have used their product. It probably is more important that the oil be changed regularly and checked for water, than the actual brand, as long as you have the proper oil.

[teflonmom]

I am a real bug about using ONLY the lubs packaged by the motor maker. The small difference in cost is not worth the worry of do I have the right stuff.

My two conts worth.

[starcrafttom]

I learned some thing this week about the lower lube. when you go to repace the lube in the lower unit of the honda, there are nylon washers on all the drain plugs. These are not to be used again. they are one time use items. they do not reseal very well. I had done my own service up until this point and when I sent the boat in to les his guys fond a little ,very little, water in the lower case lube. hes said it was because of me reusing the washers. so repalce your washers.

[Jon - CLou]

Very good point, Tom. Also pay attention to your torque values when tightening the lower unit screws and oil drain plug. I have a bad habit of over tightening bolts and screws and paying for it later.

Today I purchased a torque wrench and it's amazing how little torque you need on these under water fasteners.

[Larry H]

Notes on gearcase oil changes:

I agree with most of the above posts.

I would use the manufacturers lube if they package their own and if they have a 'synthetic' or 'extreme service' use that.

Otherwise, use Pennzoil or other top brands matching the recommendation from your owners manual.

Yes, do get new plug gaskets and use a torque wrench.

Use a gear-oil pump (Lubrimatic, fits a 1 qt bottle and has a screw-in fitting on the end of the hose), and fill gearcases from the bottom till the oil runs out the top hole(vent). Then put in the top(vent) plug, remove the pump fitting, and put in the drain plug. By putting in the top plug first, very little oil runs out while removing the pump and installing the plug. Then torque both plugs.

It is important to fill the gear case completely from the bottom to purge any air. If the gearcase is not filled completely the top bearing on the driveshaft can run dry and fail.

[thataway]

At least the Suzuki and Yahama 4 strokes have washers on the engine oil which also need to be replaced with each change, as well as the lower units nylon washers. I buy a dozen at a time, so I will always have new ones. Agree with Torque wrenches for tightening.

[ahpeterson]

I'm preparing to do the 20 hour maintenance on my pair of BF50 Honda outboards. Does anybody know what size nylon washers the BF50 requires on the lower unit plugs? Also, how much torque should be applied to the plug screws when re-fitting them?

Also, I'm curious about what sort of store will sell the gear oil I require. The local West Marine (Edmonds) just has their own brand, and I'd really rather purchase either Honda specific gear oil or something by one of the well known manufacturers. Any suggestions?

I've got a service manual on order but any info anybody could give me on these items would be greatly appreciated. Thanks!

Alec

[flapbreaker]

Do the torque wrenches come with screw driver tips or just socket type? THe Honda's don't have a hex hed type screw but do have a philips head. Makes it hard to loosen them it seems.

[IT-SEA-BIT-C]

theres better /without gettin to techinical i'll just say AMSOIL i've abused a lot of lowers and have seen differences when tearing down for re-builds.i swear by it .not knocking mercs oil but u asked for better. ..john

[Larry H]

Alec,

Why don't you have your dealer do the 20 hour service?

If you have any warranty problems later it will be much easier to deal with if you have proof that the dealer did the service..

The dealer service techs know what to do and what to look for on the 20 hour service. That service is a chance for the factory trained techs to verify that your motor is operating properly.

If you are still going to do your own service, buy the oil and plug gaskets from the dealer. Also buy a gear oil pump and fill the lower unit from the bottom up. Find out what the correct torque is for the screws. Don't forget to buy a torque wrench!

If you strip the drain and fill plugs, that's not a warranty item and could cost you a new lower unit housing and the labor to install it. If that happens, you will only have a shop warranty (maybe 90 days) on the rebuilt lower units. If you don't tighten the plugs enough, and water gets in, you have to pay for the repair. (your failures are not covered by warranty)

Have I convinced you to have the dealer do the service? In my opinion, the amount of money you could save by doing your own 20 hr service is not worth risking damage to the lower units and not having warranty coverage.

Larry H

Retired outboard mechanic.

[Larry H]

Spencer,

Torque wrenches have a square stud either 3/8in or 1/2in onto which you install the correct socket. Sockets are available with screwdriver tips, both phillips and straight. Check a good auto parts store or Sears. Buy a quality socket. Cheap ones will strip themselves.

Be sure that the tip fits the screw, too small a tip can strip out either the screw head or damage the tip.

PS: See the post above to Alec.

Larry H

Retired outboard mechanic.

[marvin4239]

I agree with Larry especially on the 20 hour service. I had a local dealer do it and they changed everything but the gel coat. It was close to $400. There are a lot of things the tinkerer link myself wouldn't notice and the security of knowing someone knowing what to look for is worth the extra expense and inconvenience. Future oil changes I plan to do myself. In the Suzuki owners manual it suggest changing the oil filter every other oil change. Does anybody actually change the oil without changing the filter. I'm also a big fan of Amsoil first because I think it's a very good product and secondly it's so easy to get. Just a phone call and it's at my door in usually two days. Expense is about the same.

[Dora~Jean]

Where can you get Amsoil, who are some of the distributors/stores?