Neu Motor Running Hot

[DRIFT_BUGGY]

Running a Neu 1512 2.5D on a Losi 8ight geared at 14T/46T (44mph calculator) with 5S 5000mah 25C/50C batteries and MMM ESC. Batteries are only around the 95F - 112F and MMM is 100F - 125F (measuring through the gaps for the heat sink) and the motor gets up to 145F - 165F (it is currently winter here in Australia although no snow etc. still warmish). I am running standard diff fluids for the Losi 8ight Roller F - 3000 C -5000 R - 2000 and measuring it with the Duratrax Temp Gauge. I read on here in the FAQ section that usually when just the motor is hot it is undergeared but wouldn't really think you would need to gear for more than 44mph. Can changing the diff fluid here at all?