Milky final drive oil

Today when I drained the final drive oil, it had a distinctly irridescent milky appearance to it, almost like pearlescent paint. Anybody have an idea of what could be causing the oil to break down that way or if it is a potential problem brewing? The bike is an '06 with about 13K on it and the drive oil was changed about 3000 miles ago using the "required" yamaspec yamalube.

Sounds like water is getting in there.

First two or three times I changed the fluid it remained milky full of molybdenum from the factory and smelled of sulfur. It diluted so that by the 4th or 5th change it was clear for me.

Ignacio said:

First two or three times I changed the fluid it remained milky full of molybdenum from the factor. It diluted so that by the 4th or 5th change it was clear for me.

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Gunny!

My changes at 600/3000 and 6500 were like that. Since I had the juice I changed it when I changed the oil the first 3 times.

Going to do it again with the next change which is due any day now.

I'm at 13k too so it's due again, but I suspect more of the same.

I change mine final drive oil every other oil and filter change. Takes just a few extra minutes and Mobile 1 75/90 synthetic is cheap enough.

twowheelnut said:

Sounds like water is getting in there.

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Thats what I suspected at first also but wouldn't there also be an indication of oil seepage from someplace?

I don't remember seeing it discolored the last time it was changed but, if nothing else, it makes me feel better that some of you other guys had the same experience. I'll give you a call when the final drive goes BMW on me....

If anything bad was going on in there, you would likely see some serious crap attached to the magnetic drain plug. I agree with the others, no problem.

I would think water myself but it could be the change like Ignacio says.

I suppose that oil is long gone? If it looks milky next time, I'd be curious if setting it aside in a clear jar might help the emulsion separate so you could get a better idea what you’re dealing with.

Why change the gear oil so often? The manual recommends a change every 16,000 miles after the initial 600 mile change.

Nothing going on back there to contaminate the oil.

Constant Mesh said:

Why change the gear oil so often? The manual recommends a change every 16,000 miles after the initial 600 mile change.
Nothing going on back there to contaminate the oil.

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Because "Mobile 1 75/90 synthetic is cheap enough."

Mesh, why does your avatar appear and disappear? Like right now, it's not visible, but in an hour if there's another post I come back to read, your avatar will be there. Weird.

I just changed it because its easy enough and I figure no harm is done so why not. Charlie mentioned the magnetic drain plug and there was really nothing on it to indicate a problem. Next time I'll drain it into a seperate container and set it aside as suggested.

I just can't figure out how a significant quantity of water could get in there. There is no pressurized water near the final drive. You will probably get a little condensation over time, but I doubt it would be enough to notice.

One reason not to change it so often is to lessen the chance of stripping the drain plug threads. I've seen far too many accounts of shade tree mechanics on this forum stripping drain plug threads during an oil change.

Do no harm as the doctor would say.

There's nothing going on back there to contaminate the oil. Certainly no soot buildup from combustion as experienced by the engine oil.

About the only thing one could do to contaminate the gear oil would be to submerge the drive in water so that water entered the gearbox through the breather on top of the drive.

I don't have an avatar.

Additional note:

The Honda ST1300 manual recommends changing the drive oil every 24K miles. So Yamaha is being extremely conservative when it calls for 16K mile changes.

Constant Mesh said:

One reason not to change it so often is to lessen the chance of stripping the drain plug threads.

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Hmm, point well taken....

Joe2Lmaker said:

Mesh, why does your avatar appear and disappear?

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Constant Mesh said:

I don't have an avatar.

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My mistake. It was ionbeam's avatar I was expecting to see. The mind is going

Try dabbing some oil on a kleenex or papertowel and look for a halo of coolant.

Up here in canada we get serious condensation foaming between seasons when the humidity is high and the thermostats stick. The crankcase vent should boil off any water unless it is clogged. Lastly, with excess condensation, an over-full sump causes excess foaming too.

It'a always a good idea to change the final drive fluids to get all the crap out of there. Haven't had ONE that wasn't full of crap from the factory (they don't clean them before assembly gentlemen). And if you don't tighten the plugs like a gorilla, you can change the oil a hundred times without any problems. I tighten them by hand since I can remember, and never a problem. Just put a new crush washer every time... or run it agaisnt sand paper on a flat surface until smooth if you don't have one handy. The reason I like to change it a few times when new is there's very little oil back there, and it does get pretty hot, so I want my oil fresh and uncontaminated there. As somebody said, a quart of Mobil1 75/90 is $8 at Autozone, and it should last 4 changes or so; cheap insurance folks. Later.

JC

Kiki said:

Try dabbing some oil on a kleenex or papertowel and look for a halo of coolant.
Up here in canada we get serious condensation foaming between seasons when the humidity is high and the thermostats stick. The crankcase vent should boil off any water unless it is clogged. Lastly, with excess condensation, an over-full sump causes excess foaming too.

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Can you draw me a diagram as to how coolant might make it into the rear final drive pumpkin. I can't seem to make the connection.