Dont run Merc oil.

The Alisyn Type 2 is pretty trick....

Neither Imco or Treague (who sells Imco) recommends Merc oil for Hi-perf/Hi-stress applications. Amsoil or Redline! Those guys gotta know a little something. --- JP

Always an API GL-3 loadbearing product. Amsoil Marine gear oil is GL-2 use the other stuff if you go Amsoil. I think lots of moly is good in the gearcase and Redline is the highest second to RP in moly. Mobil-1 exceeds GL-3. I use it.

The smell in some cases is when water gets in and emulsifies it lets bacteria grow and stinks. Change often and use syntehtics. The others foam when water gets in that can't be good either.

Yes Hydro--. I should have said NOT Amsoil's marine gear lube, but their 75-90 series 2000 "race" offering. It doesn't have the additives to protect against corrosion from water leakage however and should be changed more frequently. --- JP

i've always run Merc Hi-Perf... with relatively good success...

now that i've waxed the alpha SS twice in one season i've decided it is time to do a little oil analysis from a clean plate... so with parts on thew way i am getting ready reassemble and start fresh...

the SS died as a result of well a log on lake cumberland so i am sure it was not the oil...

i generally change oil 4 times a season.. every 25 hours or so, bout the same for engine oil... the stuff always looks pretty much like the day it went in and smells about the same... (like CRAP). I run my drivetrain pretty damn hard too... i replace fluids often (probably too often) because they are much cheaper than steel...

I've been searching a lot of local marinas looking for used gears to compare to whatever is inside of my SS gearcase (it is a looooong story) so that i can put the proper stuff back into it... anyway.. what i've found in even used gearsets is a lot of surface degredation on the pressure side of the gears. pitting, flaking and gaulling through the surface hardening mostly. none of these gearsets were broken... just worn or the gearcase was damaged and things stripped apart for rebuild etc. i've been through alpha gears, 3.0 litre OB gears, 2.5 OB gears, etc etc etc...

The first round on fluid change i've decided will be 10 hours on Merc Hi-Perf followed by Torco RTF (this stuff used in a whole lotta winston cup gearcases and rearends so i am curious)... then onto Amsoil, Redline, RP, etc... hopefully i can come to some conclusions by next summer... i am stocking up on oil analysis bottles...

any other thoughts for my DOE???

JR

Jaroot--It's interesting that you mentioned Torco. Two years ago I was talking to a guy who has wrenched on some serious boating iron to include recently Extreme Exhibit. I mentioned I was running the Merc High Perf in my Speedmasters and asked if he knew of anything better. He indicated Torco and I swear he said that I could get it from Mercruiser if I called them??? I had planned on stopping by and asking him about drive fluids and a few other things. I'll make a point of it this week and see what their current thinking is. --Lou

everyone can correct me if i am wrong but i believe that TORCO MTF is spec'd by merc as the ONLY oil for use in the #6's...

anything else will run the RTF...

Jaroot-- Now that you mention it, the individual I was referring to does have a lot of experience with #6's.--Lou

Well, my first drive wore out it's clutches. That was some stinky oil. Almost had to hold your breath around it. Nasty. This oil only had a tinge of that odor. Not objectionable at all.

Many members on this board chose to use their own mix of oil. I know that some have run into problems such as foaming. I put the question to one of the designers of the bravo series of drives. He was pretty frank with his response. Merc had tested their products. What they found was that they all add their advantages. The problem is that they all had disadvantages. Things like temperature break down, foaming, etc. The merc oil was blended to combine the best of these properties with the fewest negatives. My opinion is the mercury designed the drive and I'm going to use the product that they designed to put in it.