I'm really sorry if his has already been asked, did some searching but didn't really see anything specific to the problem I'm having.

Just got back into the hobby after about a 10 year break

Picked up a nitro rustler and it runs awesome. But when I hit the power it pulls to the right. I played with the slipper clutch a little but no serious improvements. When holding the spur gear, the right wheel seems to spin more freely than the left. Is this a diff issue? I've heard people say is has oil and I can change to a heavier oil. The last time I went into a tranny they were just greased, but that was 10 years ago! lol

Thanks in advance!