[othello]

By using a 30k instead of a 10k diff oil in your center diff, more power will be channeled to the rear of your truggy which might lead to faster acceleration (wheelies might become an issue though). This can only be achieved with more power put to the ground which equals to higher peak Amp draw which normaly translates to more heat.

On the other side you will apply throttle more gently as the car is likely to wheelie. Long story short it really depends on your throttle management how hot your motor gets. My eagletree logs showed higher amp peaks with higher diff oil in the centerdiff when using full power. But with lighter centerdiff oil you might constantly trying to use full power (more full throttle) which could also lead to a hotter motor, eventhough peak amps are lower.

I wouldn't say a motor runs hotter only due to the fact the center diff is too loose. It's a combination of a lot of variables.