Gear Oil Questions

[l008com]

I usually head down to West Marine and pay top dollar for gear oil every season. But is there a gear oil I can get at an autoparts store that will work as good, or better, and cost less?

Second, very related question. To change this gear oil, you have to remove two screws and these screws have a type of O ring on them to keep oil in and water out. They're not normal rubber O rings, they're kinda like flat discs. Do these have a name, and is there a way to find exactly which ones I need so I can order online from a site like *this* one?

One last question. Looks like lots of gear oil comes in non-standard shaped containers. These container won't be compatible with the little pump you need to get the oil up into the motor. I have plenty of left over 5w-30 motor oil containers, I could use one of those and just pour the gear oil into that. THE QUESTION IS: Will a little but of 5w-30 residue, and I mean residue, affect the gear oil in the lower unit? Or is that fine?

 

[jimmbo]

Some people will insist that you can use Regular Hypoid Oil in the Gearcase, and others that will say that the Marine Oils are superior. I tend to be in the Latter group. These are small Gears, much smaller than what are found in Vehicle Differentials, yet they have to contend with very high Loading. Marine Oils often have higher concentrations of Extreme Pressure Lubricants.
Go to the dealer and get the Orings/Seals for the Drain and Vent Screws. They are not that expensive.
Rinse the Bottles out with some Brake Cleaner, it will get rid of oil quite well.

 

[racerone]

Agreed with the above post.-----You might forget that you put gear oil in another container.------Gear oil is cheap.------And if there is no water getting into the oil you do not have to change it every season if you run say 50 hrs.-------Many vehicles run for years and folks rarely change oil in the differential.-----30,000 miles equals ~600 / 700 hrs I say.

 

[Faztbullet]

This is what I have been using for years on my customers and personal motors ...Mystik JT-4 sold at O'Reillys. Its is colored blue.

 

[Chris1956]

Any Marine gear oil for mechanical shift motors (that is what you have?) will work fine. Wallyworld plus many automobile parts places have them for less than $10/qt.

Gearcase gaskets are available at marine stores, sometimes at wallyworld and on amazon. Keep a supply of them on hand. Mercury ones fit both Merc and Johnnyrude. Yamaha's may be different as they use an adaptor on the gear oil pumps.

A bit of residual 5W-30 oil in a container makes no difference IMO.

 

[airshot]

Years back I switched to full synthetic gear lube...I know, another syn oil thread....nope, I found a definet improvement in shifting anf performance in both I/O mercruiser, and my Jonnyrude motors. I normall use the walleyworld oil as it is Valvoline gear oil. My recent purchase of a 92 Merc 40 hp 4 cyl has nice clean/ fresh lube in it but will change over at end of season

 

[Chris1956]

I use full synthetic on my '98 Johnny 150V6. It pushes a heavy boat, for hours on end. I also use this boat in cold temps.

I use dino stuff in my '93 Merc 135V6. It pushes my speedboat which is light, and used in warm weather only.

Does it really make any difference? Not that I have seen. I have never needed to repair or replace a gearcase. The only seal I replaced was a shift seal.