Lower Unit Gear Lube

[Langer]

Does anybody use synthetic lube in your lower units? It was only like a buck more then regular. She did say that once you go synthetic you cannot change back to regular. Anybody have any opinions on this?

Also how much is needed to change it? The lady told me I only needed one it doesnt seem like enough. Its an Early 90's Mercury 115 Hp.

Thanks,

[Cy]

I normally love synthetic oils and lubes.  I run synthetic in both my car and truck engines.  Synthetics are good because all the molecules are the same size and flow around and between much better.  They are worse if you have any kind of leak because they will run out on the ground faster too.  I would think a synthetic lube in a lower unit would be nice, because they dissipate heat better and less likely to break down.

As far as not being able to mix synthetics and conventional lubes doesn't sound right to me.  I have never heard of a case when that was true, but I maybe wrong and you should look into that further.

Cy

[Langer]

I just found the notes that the previous owner left me, and he used the synthetic, so thats what I will continue to use.

[djkimmel]

I've consistently been told never mix regular lube and synthetics at all, but I could switch between the two as long as I let the other completely drain out first.

I would get an updated recommendation from a certified repair technician first again before I would make the move myself.

If you had synthetics before and you want to continue with them, you don't have to worry.

[yukonjack2]

I switched to synthetic amsoil gear lube last year and had no issues. 
I like the idea that synthetic is unaffected by water intrusion, and the lower unit will get water in it at somepoint.  Note at the bottom it is compatable with other synthetic as well as conventional oils as well.

http://www.amsoil.com/StoreFront/agm.aspx

I plan on putting a gear bersion of this in my trailer oil filled hubs as well - tired of changing the conventional oil in them a few times a season as they get milky from water intrusion as well.

Jack

[REEL_MAN]

I have used synthetic oil for years in the lower unit as well as the oil I burn in the gas.  One of the main reasons to use synthetic in the lower unit it can take heat better than conventional mineral oil. If your lower blows out of the water when you go over a wake or wave and you hit the rev limiter you have just burned std. mineral oil, synthetic won't be hurt.
Go with the synthetic you can't go wrong.

REEL_MAN

[Anthony Adams]

I would get an updated recommendation from a certified repair technician first again before I would make the move myself.

The guys from Royal Purple gave everyone at the ABA Nationals a free lube change. They claim an additional 2-3 MPH our of their lube.

I talked to them and the ABA/Merc tech on hand and they said you can drain your unit and switch back and forth between the two with no problems but they recommended to drain the unit as best you can but a little mixing would not hurt.... Yet could make the product less effective..