[tf]

Seems to be a lot of different opinions on weather to fill to spill, or go by the book when changing the front and rear diff oils. My whole life i've done fill to spill on all the gear boxes i've come across. Of course i'm old so my ways might be obsolete. I have heard cfmoto used to say fill to spill but then changed it to less? If so, anybody know why?  Anyway, how many do the fill to spill and how many go by the book? Has anyone noticed any difference in performance by using either method?

[NMKawierider]

The Chinese do not share the same traditions on gear case of diff fill port locations as the west do. Filling to the bottom of the hole is well overfilling it and in many cases they sling lube up and out the breather and actually cause it to run hotter. I too am from the Western old school and have always filled mine to the hole...in fact I even jack it up a little on the fill side of others to get just a hair more..(which also isn't a good idea).. in but with CFMoto this is really a bad idea which leads to problems....especially for people that ride extended higher speeds on roads. I don't usually so I hadn't been worried about it but have had some rear case overheating and oil out the vent dripping on the muffler shield..stinking..so as I change them...and as I put my front diff back to service, I will be filling it as per the book which is .28 liters or 9.46 Oz. I'll probably round up to 9.5 or so.

So yes, only with CFM, go by the book. Sorry for the long read.
 

[bwzforce800]

Seems to be a lot of different opinions on weather to fill to spill, or go by the book when changing the front and rear diff oils. My whole life i've done fill to spill on all the gear boxes i've come across. Of course i'm old so my ways might be obsolete. I have heard cfmoto used to say fill to spill but then changed it to less? If so, anybody know why?  Anyway, how many do the fill to spill and how many go by the book? Has anyone noticed any difference in performance by using either method?

Most of us fill to the recommended amounts listed by Cfmoto , if you don't , they puke fluid out , with some brands of fluid it will still puke some out but we've found that Mobil 1 is a good fluid and doesn't expand as much as some the other brands so less chance of it puking fluid out the vents

[tf]

Very good info ...thanks  i have a 2022 zforce 800 trail
 
  "filling it as per the book which is .28 letters or 9.46 Oz"
 I have a 2022 z800 trail and my book shows 11.2oz for the front diff. 13.5oz for rear. I guess its changed? Maybe my manual is outdated?

[NMKawierider]

Very good info ...thanks  i have a 2022 zforce 800 trail
 
  "filling it as per the book which is .28 liters or 9.46 Fl Oz"
 I have a 2022 z800 trail and my book shows 11.2oz for the front diff. 13.5oz for rear. I guess its changed? Maybe my manual is outdated?

There were some drivetrain changes made in 2018. Maybe they beefed them up a bit.

[NMKawierider]

Here's an interesting note. Just came in from re-filling my front diff with lube after a complete flushing with brake parts cleaner. Per the book it should take .28 liters or 9.46 fluid Ozs...and from what everyone says this should not be to the bottom of the fill hole yet..and yet..it is on my 2015 Z8. In fact it started running out at at that. So...let's hear for others going by the book and their results. I'll run it a bit then re-check it to confirm but looks like at least the fronts on the older units are to the fill hole.

[mpgo4th]

I fill to the book spec on my machine. I too have noticed that the front fill amounts are off. With my 800ex they are all correct and take what the book says but my 400 and 500 4 wheelers both overflow the front diffs before the specified amount of oil is in them. I think I can only get about 200ml in the front of my 400. And also the rear is a revised part from the older ones. It is a beefed up unit and might take more oil.