Racers please chime in--Thanks

Change everything (oil, trans, diff) at beginning of season using synthetic fluids, then the oil again somewhere halfway through the season. I've averaged over 150 passes/year for the past 2 years. It may be overkill but is worth it for me since I also do a few thousand street miles on top of the racing (I rarely trailer my car). Many guys I know just change the oil once a year and trans fluid every other year with good luck. You just need to figure out what works for you.