FJRiders.com

I changed the rear diff oil, filled it to almost overflowing..then drained it after a ride, measured it and found it to be 175ml...I “borrowed” one of my wifes measuring cups and refilled it with slightly over 200ml...

Should I be concerned that the rear diff was run with only 175ml in it?

I wouldn't worry about it unless there was an excessive amount of metal stuck to the magnetic drain plug. More than the usual smear of black sludge. Since your bike is new, a little more than "normal" is expected anyway.

CollingsBob wrote: ↑Mon Jul 23, 2018 12:21 am I changed the rear diff oil, filled it to almost overflowing..then drained it after a ride, measured it and found it to be 175ml...I “borrowed” one of my wifes measuring cups and refilled it with slightly over 200ml...

Should I be concerned that the rear diff was run with only 175ml in it?

Fill it to the lip. Done.

No worries. Done. Fin. End.

A couple of thoughts...

1. It's a Final Drive not a Diff. A differential is used when there are two tires and power is distributed in possibly more than one direction. But that is not useful information.

2. Are you doing this with the bike on the centerstand? That would seem obvious but I have to ask because it will have an effect.

3. Fill the drive to the bottom lip of the fill hole. Put the plug back in with a new crush washer. Forget about it until you feel like changing it again. That interval is up to you. I do mine every other oil change because I am stupid.

YMMV

The bike is on the centrestand. There was nothing on the magnet, I’ve been changing the final drive fluid at every oil change just because oil is cheap

Recommended interval is every 2 years... I do mine at least every year. The dark stuff is moly assembly lube, which gets less with every change. What Wheatie says, keep it simple, no need to measure anything, capacity spec is with totally dry which yours isn't. Do not rotate the wheel when filling, it will overfill and blow out the vent.

The fact that your oil is coming out looking pretty much the same as it did when it went in is a pretty good indication that
1) Nothing bad has happened to your final drive
2) You are wasting oil!!

I used to do mine every second oil change (8 to 12,000 km interval for engine oil, depending on conditions and trip plans). Rear drive lube maybe twice per season now - typical season is 35,000 km or so. Still looks pretty much the same coming out as it did going in.

Note: As with the engine, capacity and the amount required to fill may differ due to "retained" fluid.