hey guys, i just picked up my new 18 Z8 ex a couple weeks ago, i have 40 km on the machine to date. i noticed a couple puddles on the floor of the garage, under the rear of the machine. i have the standard issue leaking coolant from the water pump (not overly concerned about that just yet). Also the vent tube from the rear diff is leaking what i assume is oil? (light green in color?) has anyone else experienced this? i wasn't able to find much information on the subject. i am going to check the oil level when i get home to make sure it isn't over filled. I called the dealership, they haven't had any problems with this before. they said to drop it off and they would look at it. I'm just wondering if anyone has a reasoning for this? or know what the problem might be, before i take it back and be with out my machine for who knows how long.

[2015 Z Force 800 53/Trail EPS]

Haven't that this one yet so let me ask- is oil coming all the way down the vent tub from the top, or is it closer or at the nipple on the case? Have you had it in any deep water lately? And does the oil smell like typical 80-90W gear lube? Do check the level and while there compare what's in it to what's leaking.

yeah it is going all the way up the tube and dripping out the end of the hose on to the motor. the bike hasn't seen a puddle of water yet! wet pavement only.

[2015 Z Force 800 53/Trail EPS]

The only time I have ever seen oil come out the top of a vent tube is when they were either VERY over filled..and I mean turned on it's side and filled, or when water gets mixed-in with the oil and gets heated. When that happens it looks milky though.

its hasn't been on its side yet lol. like i said i wasn't able to find much info on it. the oil is light green color, looks clean, not milky, but i'm not sure what color it is to begin with. ill check the oil level when i get home and go from there. i might have to take it to the dealer to check it out.

I checked the oil level, it appeared to be level with the bottom of the fill plug hole. so to leak as much as it did and be at the proper level it would of had to have been over filled. I'm going to drain and replace the oil so i know for sure it has the proper amount. we will see what happens after that.  the manual recommends 80w90, anybody run anything different for any particular reason? 

[2015 Z Force 800 53/Trail EPS]

I checked the oil level, it appeared to be level with the bottom of the fill plug hole. so to leak as much as it did and be at the proper level it would of had to have been over filled. I'm going to drain and replace the oil so i know for sure it has the proper amount. we will see what happens after that.  the manual recommends 80w90, anybody run anything different for any particular reason? 

I was running a synthetic 75w90 but am having some issue with mine not related to the oil so I went back to the 80w90 conventional. I don't think it matters much so for now I stay with what the book says.

i drained and replaced the diff oil. it doesn't seem to be leaking anymore. i only took it for a short rip after changing it out(about 25km) . I will keep you posted if that changes.

I'm having the same issue with mine right now. Just curious if the oil change you did resolved the issue?

I'm having the same issue with mine right now. Just curious if the oil change you did resolved the issue?

Mine just started doing this, too, but after long, high speed runs. 

[2015 Z Force 800 53/Trail EPS]

I'm having the same issue with mine right now. Just curious if the oil change you did resolved the issue?

Mine just started doing this, too, but after long, high speed runs. 

Something of interest about this subject-if you go by the quantity listed in the manual for the diffs, it won't take it to the bottom of the fill port...like most of us do...including me. Those that fill it to the bottom of the fill port have this issue of enough being slung-up against the vent port and the expanding air from heating pushing it out the tube where those that just put in what the manual says..don't seem to have this issue. As I too am getting some out the vent tube I think I will just put in what the manual says next change...which for me and my issue with mine, won't be long.

Of course water or moisture in the oil will turn to steam and blow out the vent too. That looks like any oil with moisture in it though...milky.

I went ahead and changed it tonight.  It was a little milky.  I don't recall getting in any deep water recently, but who knows. 

I checked the service manual and it is says periodic oil change is 250ml but capacity is 300ml.  That certainly supports your idea about how we may be overfilling it if we fill it to the top of the filler hole.  Doesn't hurt to have it leak out in IMO.