The only problem with running with the RTR grease for racing (as they now come built...mine was a bag of bits!) is that you'll have no benchmark for tuning, any oil will be softer than the grease but give different resistance and temperature working tolerance...also a different feel to the car i would have thought... the grease in them is usually very thick and a pain to clean out going on experience with other Losi RTR gear diffs!
I started with 3K and went upwards, with each grade it improved.
Remember to bed it in before running it... hold one wheel and apply power, starting with low power and alternating holding each wheel.
I changed the oil in mine after a couple of runs to inspect it and there was some light swarf from bedding in, best to get rid rater than having increased wear rate on gears.
Just keep an eye on outdrive wear as they are softer than the ball diff outdrives
The car will instantly accelerate faster and brake a lot harder, it does feel completely different at first and you will have to adapt a little when taking jumps so take it steady to start with!
Hope it works for you matey,
Mark
