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I was told by an out drive specialest not to run Amsoil gear lube in a out drive that has been rebuilt(new gears & bearings). He said to run mercury gear lube in it for the first 6-8hrs for break in time so the bearings & gears will "wear in". He said running Amsoil in a freshly rebuilt out drive is like running a full synthetic oil in a new motor and trying to get the rings to seat. It does make sense but I have never heard this before. Is anyone else doing this?
Gears and bearings don't "wear in". They are machined to an exceptionally high precision right out of the box.
You either have a film of oil between the gear faces or you don't. And when you don't, the results are galling and pitting. Not some sort of "mating of surfaces". And there's nothing wrong with the merc lube- lots of racers and many, many individuals running big power use it with good results. It doesn't have any properties that accommodate gear wear-in.
Yeah, I agree with above. In an engine, its a different story. In your drives, I wouldn't worry about it. Go ahead and put it right in.Quote:
Originally Posted by ozarkdevil
no difference really.... as stated above...
The merc oil is a hybrid oil and the amsoil is full synthetic but both good oils.. I run both and haven't seen any difference between the two.
Though micro polished gears must develop a wear pattern, running syn will prolong break in! But what the heck do mechanics know anyway!
correct !!!!!!!!Quote:
Originally Posted by oldphil
Never used a micro-polished set of gears but pretty sure new gears from mercury are shot-peened.
To be honest I've never really noticed a difference either way whether it was 300 hp or 800 hp.
Only thing I've ever done was limit WOT passes and vary rpms during first 10 hours and first oil change.
That's been working pretty well for me over the years but I guess results may vary. :)
Welcome.......Quote:
Originally Posted by Oldphil
I'd like to agree, but that would be rude on your first post...
Keep on givin em heck.....:sifone:
If anybody has done any more testing than Smitty on gears, I'm not aware of it.......Quote:
Originally Posted by Geronimo36
Send him a PM and see what he's found out......
I've seen some of the stuff Smitty's been doing on drives over the years.
I would say from experience that more important than the kind of oil used to break in the drive is the way it is driven and a oil change right away if running big power and tall props. The gears do need to take a set before being thrashed on if they are to last (this is in 500 plus hp or heavy boats). A stock boat with low factory power I doubt it would make any difference. The peening process that mercs using currently on their lower gears sure seems to create alot of fine metallic in the oil,I have seen lower gears that went in at .010-.011 b/l open up to .014-.015 and the rough peened surface was polished from gear contact to the point of being smooth in less than 25 hours (again,this was with considerable hp). The gears I have tested with using cryogenic treatment and a multi-step polishing process like to be installed looser and they seem to hold their b/l with maybe a gain of .0005 after taking a set/breaking in up to the point where the outer hardness begins to fail from core material shifting around and gear face starts coming apart (stock ones do this too from big power,they just seem to do it faster than the treated ones),Smitty
this gear pictured is one where peening is worn off and its starting to gall ever so slightly and wear off outershell.
This is a used then treated gear that lasted 3x longer than stock new ones,this pic was after running 25 plus hrs at 950 hp level while testing,the gear set was ran another 30 plus hours after this pic before it started having the typical light failure on the face of teeth.
These were stock ones after 25-30 hard hours and a hard day of tuning with crocket on the st claire river with at least 5 oil changes in between to remove metal and at least one inspection teardown while they were still runnable,Smitty
Thanks for answering Smitty. You are still keeping the crazy hours I see.......
So you wouldn't beat on anything 500 HP or more without changing the oil at 10 to 15 hours?
I guess if it was a light twin or single with a hp-500 or similar I would probably go longer than 10-15 hrs,what I mean is when you start making 650-700 plus hp/ft lbs tq or if your boat is extremely heavy a shorter interval is needed. A added benefit of short drive oil change intervals is you can watch how much metal you are getting in the oil and on the magnets,when you see too much you tear drive down and inspect. If you had just kept running that same drive a part might have starte really going away and you wouldn't catch it before it took out all the gears,bearings and possibly the case.Quote:
Originally Posted by Ratickle
In 9 years of running Bravo's behind big power I have never had a total drive failure ,never junked a case or had all the teeth get knocked off a gear from a bearing wiping out. I have torn a drive down to inspect it (because metal was excessive in the oil or on the drain plug and found parts on the verge of failure that would have wiped out everything,Smitty
if you want to save money, mercury gear lube IS TORQUO i bought a five gal jug one time , pulled off the label and there it was TORQUO OIL