im going in for my 15k checkup and was thinking about having my diff and tranny fluid changed. Should I let them do it or should I do it somewhere else. Would honda put mobil 1 synthetic in the differential for me if i bought it ahead of time?

 

Honda will most likely NOT put in Mobil 1 in your diff. Just make sure they DO NOT put in anything that they would put into the diffs of their CRV's and Pilots (VTM fluid). They can get a hypoid gear oil from their motorcycle division.
For sure, have the diff fluid changed. Have a look here:
http://forums.s2ki.com/forums/showthread.p...threadid=200323
If you don't mind the added expense, then sure, do the tranny fluid too, but if your tranny is functioning to your satisfaction, you can leave this another year.