Before I drain the old, is there a special oil for the rear diff, or will any diff oil work?

thanks
D

honda fluid only any other will damage the differential and may overheat and cause breakdown or permanent damage and siezure of gears

Dual pump fluid from Honda

Honda recomends You buy thier fluid. You do not only have to use Honda gear oil. There are much better lubricants than Honda. I use Royal Purple synthetic in my car . I have also used Mobile 1 sythetic. You will probably need GL-4 or GL-5. Ask your dealer for the weight then you can find a product better than what honda offers. I have never had any problems