I have a related question....I haven't seen too many posts on people "upgrading" to say a high quality synth from Royal Purple or Redline in place of the OEM Isuzu fluids...is everyone simply going to the dealer? Quite frankly I'd like to go to my local performance shop and fill up with Royal Purple products. Especially after my local dealer changed their "service" intervals three times in one year, none of which match the service intervals in the driver's manual. To boot, cost jumped from high threes to $500 big ones.

I do know that the rear differential would require a friction modifyer (available from Isuzu and I'm sure from RP or Redline).

Any thoughts? Anyone doing fluid changes in the driveline themselves?