Lower unit oil for 200 optimax

[poopsdream]

I have used the purple in automotive applications I am not sure if it has a marine rating on it.I personally would use only a marine rated oil.Most of the marine rated synthetic gear oil can handle up to 10 percent water contamination if it gets in the lower end.I run a Amsoil Marine synthetic gear lube75W/80W-90 never had a problem.

[PhilAddison]

jsjohnsondds wrote: I just changed the lower unit oil on my 200 optimax. The book recommends mercury high performance gear lube+. I used royal purple synthetic 75w80. Has anyone else used this? Will it be ok to use? Thanks for comments.No knowledge of that application. Why would you put anything in the gear case without having knowledge whether it works or not? I wouldnt use anything but the recommended gear oil. Friction builds heat and heat kills bearings and gears. In some cases it could be sooner than later.

[JohnM17]

Ive been a huge Amsoil fan for years. Im running it in my mower and other things around the house right now. I had some of their Marine Lower Unit Gear Lube that needed used up so I put that in my Pro XS LU the last time I changed it. The Merc HP gear lube actually out performed the Amsoil and all others in the last comparison I read in most testing. The Amsoil was best at water intrusion. There is no perfect formulation so I cange it at least once a year or every 100 hours. At the very least it would need to be Marine Rated.

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