Walmart, Meijers, pretty much any automotive or hardware section has a bunch of different stuff that is basically the same. Try some goo, goop, or whatever funny name one they have and it'll do the trick. I've used many of the different brands and all work well.
Team Associated & CRC toy cars, Trackstar motors/esc's, Spektrum radios.
Keeping racing fun and affordable with my 6 year olds :)
The best track I've raced is the one in my backyard!