hi guys,

i have heard that with my matrix arena tr that it runs diff 'grease' standard & that if i replace this with diff 'oil' it improves power?
if this true or just another myth?

thanks,

Yes. Running only grease in your diffs allows more power to be transfered to the opposite wheel, usually the wheel with the least amount of traction, for example when turning a corner with lots of throttle you may notice the inside wheel balloons a lot, this is because the outside wheel has lots of weight transfered to it because of the cornering forces and the power (from your engine) is transfered down the easiest path, which is the wheel with the least amount of "weight" on it...the inside wheel.

The thicker the oil in the diff (and you need to condider the centre diff as well, because this dictates the power transfer from front to rear, not side to side) the harder it is for the diff to transfer power to the opposite side therefore more power than before will go to the wheel with the most "weight" on it.
The thicker the oil the less side to side variation of power, all the way up to locking the diff (which would make turning very hard because the inside wheel needs to spin faster than the outside wheel).

Sometimes a beginner will actually drive slower around a track with oil in his diffs because it is easier to spin the car out with both wheels spinning (if you dont control the power) than with only one wheel spinning too fast.

There are some good articles around that explain about diffs and setups way better than I can!

Hope this helps a little.