Milky gearbox oil?

[Boxing]

Hi all, my gearbox oil looks a little milky, however it's a new oil I've been using it's a lighter 5W30 or 5W40 "racing" transmission oil.

https://scontent-lhr3-1.xx.fbcdn.net/hphotos-xap1/v/t1.0-9/12376070_153312508364129_6504198108969105025_n.jpg?oh=a8a02986ce8803a0c89fd0e29843635b&oe=56DEFF57

Possible head gasket failing, or oil just been in too long?

[ScaredyCat]

Don't quote me on it but that suggests water is getting in to me. Perhaps condensation? Does your coolant have oil in it?
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Honda CBF125 ➝ NC700X
Honda CBF125 ↳ Speed Triple

[Ste]

The coolant level has gone down?

[Boxing]

[Taught2BCauti...]

If your bike has an air filter box, take a look inside to see if you have any signs of moisture or oily sludge.

Could be that water is getting into the oil through one of the breather tubes that connect to the air box.
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Honda Varadero XL125(V8)
www.TheFutureIsHere.eu

[Boxing]

[temeluchus]

loose breather hose? Lots of short trips?
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Some shite cruiser. Now with guns and FREEDOM!

[Boxing]

[Rogerborg]

[Boxing]

[RhynoCZ]

I think the water in the gearbox is just condensation from all those short runs, you don't really let it warm up before you go either, do you?

Also, if you park it outside, check the oil filler cap is alright. A very improbable scenario is, the cap is damaged and not sealing the filler hole, so rain water can get through into the gearbox, but I very doubt that.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Robby]

Coolant doesn't go anywhere near that gearbox oil.

Gearbox oil can go a bit grey a milky looking over time, much the same way as fork oil does. It doesn't get contaminated in the same way as engine oil, but it does get chopped and foamed a lot. It also doesn't have a filter to pull contaminants out, they all sit in the oil.

In short, gearbox isn't a problem - but fix all of the other problems that you know about.

[Rogerborg]

Yup, I'd go with running cold in moist air, hella light oil, all is proceeding as you might have foreseen.

Why "racing" oil for what sounds like a short trip commuter?
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[RhynoCZ]

OP, gearbox oil is cheap for a reason. The wet clutch is the only reason why you have to regularly change the oil. When you buy 99% of brand new cars with a manual gearbox, the only gearbox oil change you do is when you do the first 1000 or so initial miles, then you refill it and don't touch it, unless the box is leaking.

What I'm trying to say is, whatever greasy that does not affect your clutch should do the trick.

EDIT: Go for the grade specified by the manufacturer of course.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[talkToTheHat]

Is your 'racing' oil more hygroscopic (attracts more water) than standard gear oil?
The GL5 in the final drive of my 535 went like that if it got very wet, like leaving the drain pan out in the rain, or as when I first had her. A year's riding would'n do that.
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Bandit. does. everything.

[bladerunner]

Lgo (light gear oil) I used in the rgv for racing would come out looking like that after a weekend racing!! This time of year the air is full of moisture and short journeys don't get the oil hot enough to remove the condensation and it'll build up with each heat cycle. Other options are water pump seal leaking or if you've been off road then my Kdx is a bugger for drawing water in thru the gearbox breather. Don't worry about the head gasket just yet but watch for coolant level dropping or gearbox oil level rising!!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Boxing]

The bike is thoroughly warmed up before it's ridden hard, or the piston would have been gone a long time ago.

[MCN]

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[misscrabstick]

My Beta trials bike got coolant in the gearbox oil because the seals went leaky around the water pump drive spindle, but you say your not losing coolant, so it must be rain water getting in some how or extreme condensation.