Gear Lube question ?

JasonG · 10-04-2015, 09:18 PM

I would get the exact type of gear lube suggested by the factory. Your lower unit is not something you want to second guess.

I own mercs and use merc lower gear case fluid. I would not think of any other brand even if it was free because it is what the factory suggests.

Happy Gourmand · 10-05-2015, 07:11 AM

Quote:

Originally Posted by JasonG

I would get the exact type of gear lube suggested by the factory. Your lower unit is not something you want to second guess.

I own mercs and use merc lower gear case fluid. I would not think of any other brand even if it was free because it is what the factory suggests.

You can put any kind of gear lube that you want in your lower unit. The big question is why would you want to put in anything other than what the factory recommends? A lot of planning and engineering goes into recommending a certain viscosity oil that will keep everything slippery. If you think you know more than the engine manufacturer about their engine, then go for it!

camp guy · 10-05-2015, 07:22 AM

JasonG and Happy Gourmand both hit the nail on the head, each in their own way, but, nevertheless, their point is spot on - follow the manufacturer's recommendation (they are the pros).

Dave R · 10-05-2015, 07:51 AM

Oil thins when it gets hot and thickens when it gets cold. You want it to stay thick enough to be effective when hot, but you also want it to be thin enough to flow when it's cold.

The #1 thing to look for is the API service rating, (such as "API GL-5"). Once you are sure the oil meets or exceeds that requirement, hot viscosity is the next thing to look at and that's the second of the two numbers (90 in your case). The last thing to look for is the cold weather viscosity rating which has a "W" suffix. You need to make sure the lower unit's required cold viscosity is greater than or equal to the oil's rated cold viscosity. Thus, 80W-90 is a perfectly acceptable oil to use in a lower unit that requires 85W-90. It will just work a little better in cold weather.

10-05-2015, 07:22 AM	#3
camp guy Senior Member Join Date: Apr 2004 Location: formerly Winter Harbor, still Wolfeboro Posts: 1,205 Thanks: 309 Thanked 535 Times in 299 Posts	Lower unit lube JasonG and Happy Gourmand both hit the nail on the head, each in their own way, but, nevertheless, their point is spot on - follow the manufacturer's recommendation (they are the pros).

10-04-2015, 09:18 PM	#1
JasonG Senior Member Join Date: May 2006 Posts: 310 Thanks: 48 Thanked 45 Times in 33 Posts	I would get the exact type of gear lube suggested by the factory. Your lower unit is not something you want to second guess. I own mercs and use merc lower gear case fluid. I would not think of any other brand even if it was free because it is what the factory suggests.

10-05-2015, 07:51 AM	#4
Dave R Senior Member Join Date: Jul 2004 Posts: 2,985 Thanks: 246 Thanked 744 Times in 444 Posts	Oil thins when it gets hot and thickens when it gets cold. You want it to stay thick enough to be effective when hot, but you also want it to be thin enough to flow when it's cold. The #1 thing to look for is the API service rating, (such as "API GL-5"). Once you are sure the oil meets or exceeds that requirement, hot viscosity is the next thing to look at and that's the second of the two numbers (90 in your case). The last thing to look for is the cold weather viscosity rating which has a "W" suffix. You need to make sure the lower unit's required cold viscosity is greater than or equal to the oil's rated cold viscosity. Thus, 80W-90 is a perfectly acceptable oil to use in a lower unit that requires 85W-90. It will just work a little better in cold weather.