Silver gear oil

[Vision]

Hi All. I changed my gear oil this evening after a 4k interval. Was using mobile 1 synthetic gear oil which looks like normal amber oil. What came out was silver in color, a little thick, and much less came out than the 180ml that went in.

For years this bike has had an issue with the gear oil bolt since I once stripped the threads trying to tighten it to the manual specs. Anyway, a larger bolt was threaded and I use a gasket putty to try to keep the seal tight. I noticed the bolt had an oil resdue on it before work began but there were no other signs of leakage. As I was cleaning the threads of the bolt a saw a small piece of metal in a thread.

How bad is this situation? What happens to the bike when the gears fail? How expensive is it to have the gears replaced? There's 22k on the bike. Thanks.

[CROSSBOLT]

22k miles or km? No matter if the gears work smoothly with little or no noise don't sweat it. Thry will outlast the bike. The silver color of the lube may be mildly concerning as to where did it originate. But change often for a while and look at what comes out and write down what you see. If it clears up don't worry about it.

[Vision]

22k km. The silver color is gear metal dust coloring and thickening the oil. I suspect the oil drained low enough where the gears started producing dust and a few shavings. By an estimate of what came out there was maybe 90ml of oil in there.

[Viper254]

If it's running smooth and still going, I wouldn't fret. Just keep changing the oil like you have done. If the rear drive gears go, they will let you know - it won't be dignified.

They're not hugely expensive to replace, but they are a bit of a pain to do.

[de dee]

If it's running smooth and still going, I wouldn't fret. Just keep changing the oil like you have done. If the rear drive gears go, they will let you know - it won't be dignified.

They're not hugely expensive to replace, but they are a bit of a pain to do.

  and change the oil HOT  befor the crap in there settles to the bottom, !!!!

[Vision]

So I switched to mobil one syn gear oil am changing it every 2k and just changed the fluids. After 2k the oil came out silver and was not as thick as the 4k changes have been. Less seemed to empty than was put in, without signs of leakage.

Am I really the only one experiencing this silver oil and oil loss?

[CROSSBOLT]

I would say yes since I don't recall any posts like this. Maybe I should check mine! No leaks, no mess so assumed the oil is still in there.

[scooterfan]

Some time ago I did some reading about synthetic gear oils. To my understanding synthetic gear oils are better than mineral oils at high and low temperatures - but slightly inferior at mild temperatures. The gearbox on my scooter always run at mild temperatures, which is one of the reasons I decided to stick to mineral oil at the gearbox. Since I bought the scooter I've had mineral gear oil in stock anyway, so I decided to use it on the scooter as well.

When I changed my scooter's gear (mineral) oil recently, I also found a very slight grey color in the oil. The  oil color was almost as original - but a very slight grey color was visible just after the drain plug was removed.

I might be wrong - but I think the grey color is caused by Aluminum dust which came from the gearbox housing.  Metal dust coming from the gears would be darker in color, and a milky oil color would be an indication of moist condensation in the oil.
So I think some moving components might be rubbing slightly against the gearbox Housing.

I am not too worried about it - the drained oil at my gearbox was still almost perfectly clean. Maybe you must just change the gearbox oil more regularly, or try mineral gearbox oil. I use 80 W 90 mineral oil at the gearbox.

My scooter has just over 16200 kms on the clock.

[Vision]

Thanks scooterfan, may give it a try.

[scooterfan]

Thanks scooterfan, may give it a try.

No problem. Feedback could be very interesting.

[scooterfan]

Just for the record - today I discovered that the silver color in gearbox oil indeed comes from a steel component rubbing against the gearbox housing.

 Today I started stripping my Agility's gearbox to have a proper look at all bearings, and discovered evidence that the far end of the rear axle (connected to the wheel) actually rubbed slightly against the gearbox housing previously.
To my mind this is nothing serious - but it points to a slight bad design which could be overcome fairly easily. The rear axle has splines winch press against the open bearing at the inside of the housing. If that bearing gets forced too deep into the housing, the far end of the rear axle WILL rub against the gearbox housing. I think whenever this bearing gets installed, it should not get forced right to the far end of the housing - a gap of about 1mm between the bearing and housing should ensure that the axle and housing do not get in contact with each other.

The slight scratches against the gearbox aluminium housing can be seen at the center of the bearing (first photo below).

The axle splines which press against the bearing can be seen at the second photo (below).

[CROSSBOLT]

Good pitchurs!

[Vision]

Fantastic scooterfan, you cleared up the confusing!

[scooterfan]

Fantastic scooterfan, you cleared up the confusing!

No problem. At the time the gearbox was opened I specifically had a good look at all components to find an indication of possibilities where the silver “whatever it was” could be coming from. The specific bearing housing at the inside of the gearbox housing was the only spot where any trace of “abnormality” could be found.

I think one possibility to prevent the shaft from rubbing against the gearbox housing could be to install a very thin rubber O-ring (slightly bigger OD than the OD of the bearing) at the far back of the bearing housing - between the bearing and the bearing housing. A thin O- ring should prevent the bearing from being installed too deep into the bearing hole, and should prevent the shaft from getting in contact with the gearbox housing.
Just a thought...

[Vision]

You're probably right.