The first time I had to change my rear differential fluid, I didn't even know I had to. I went to the Honda Dealer and mentioned that the car lurched a bit when I did tight turns. Never thought of changing the diff fluid, as maintence was reccomended at 90K as per manual and I had 60k miles on it. They changed the plan to q30K for changes. Is there a happy medium? does differential fluid age according to how old it is? Use to get it done for $39.99, now it is $79.99. Honda dealer said it was because the price of oil went up.