# Lower unit lubes, let's talk



## TomFL (Oct 2, 2007)

Is there any performance or protection difference in running Merc's "High performance gear lube" and their "premium gear lube"

What other quality lube choices are out there? Is there any benefit to running something else?

Anyone running anything different in their lower units? If so, have you noticed any difference?


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## Brett (Jul 16, 2008)

Just like wheel bearings, any quality brand lube will protect your metal.
What's more important is inspection, detection, correction.
In other words, regular maintenance!

   



> Your owner’s manual and your trusted marine mechanic will
> recommend that you should change the oil in your lower unit every
> 100 hours or six months - whichever comes first. When was the last
> time you changed your lower unit oil? It takes less than ten minutes
> ...


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## TomFL (Oct 2, 2007)

Funny thing happened today. I went to Wally World with a list of stuff to pick up figure while I'm there I'll get some merc premium gear lube. $5 and change, but they were out. 

Went down the street to a marine parts outlet place (noticed outside they had an old-looking, used, really sun bleached 6 gallon tank for sale that had a $15 price tag on it. Just saw the exact same one at wally-world for $16 new....) and they wanted $12 and change for the same quart of gear lube. 

Now I'm not cheap, but I've got plenty of time to work on this motor so I'll wait to get it at wally world. 

I figured I'd try at the dealer on my way home as I needed to get new gasket washers for the lube drain screws. Dealer wanted just under $17 for the same stuff. 

I'm all for shopping local whenever possible, but not at 2-3X the price. I've got a few motors that I change the oil on frequently so I go through this stuff fairly regularly. At the dealer's cost it would put me in the poorhouse! 

-T


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## Gramps (Nov 1, 2007)

Wow! Which place? Just so I know where to avoid. 

That is pretty wild though, you would figure they may be a few bucks more. But damn.


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## noeettica (Sep 23, 2007)

Eventully All my "Feet" will Have AMSOIL


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## Brett (Jul 16, 2008)

OK, all your feet will have amsoil,
but do you fill from the top or the bottom?


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## TomFL (Oct 2, 2007)

> OK, all your feet will have amsoil,
> but do you fill from the top or the bottom?


Although I've always filled from the bottom as per manuals, I've always wondered what difference it makes. 

-T


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## Brett (Jul 16, 2008)

Not sure exactly why the manual says to do it that way.
Every time I tried per the recommended procedure,
I ended up dripping lube everywhere trying to get
the lower screw back in place. I finally ended up attaching
a piece of tubing to the tip of the lube tube and filling from the top.
I'd rotate the prop to work the air out of the gears and fill to the 
level of the top hole. Made for less mess.
Maybe that's why they say fill from the bottom,
you use more lube due to spillage, they make more money.

There is a reason to fill from the bottom.
It has to do with an airpocket that can form at the top,
Found an explanation in a how-to:

http://www.nitroowners.com/projects/lowerunit/lowerunitproject.htm


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## nicklarson (Jan 16, 2007)

The thing about lower unit lube is diffrent engines lower units gears have diffrent gear clearinces.If its a smaller one they use the high pro stuff if its bigger the use the regular stuff.So u need to check with the manufacture about what to use and not all modles are the same.And u fill lower units from the bottom because if u fill it from the top air will stay caught in it.


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