With roughly 30,000 miles on the odometer, the time has come to swap out the transmission and differential fluid on the MPmoto FR-S. It probably wasn't absolutely necessary to change the fluid at this point based on the amount of metal shavings on the magnetic drain plugs, and I haven't had much issue with the notorious second gear notch that many complain about, but since this car is autocrossed regularly during the summer months, it's not a bad idea, and because of how the MPmoto FR-S is used, upgrading to Motul fluid is a great option over the factory stuff. 

I went with Motul Gear 300 (note: not the 300LS, which stands for limited slip. While the FR-S does have a limited slip differential, it's a torsion limited slip that doesn't require the friction modifiers found in the LS fluid) in both the transmission and the rear differential because it's popular among FR-S/BRZ/86 drivers, and I've had nothing but positive experiences using Motul products in my dirt bike and sportbike in the past. 


  • Weight | 75W90
  • 100% Synthetic
  • 2.2 Liters for Transmission
  • 1.3 Liters for Rear Differential
  • OEM Subaru Crush Gaskets


Changing the transmission and differential fluid in an FR-S is a straightforward and doable job for anyone capable of changing their oil. There's plenty of space to reach everything with jack stands. The Motul bottle is also super convenient in its' design since it has a flexible plastic nozzle that helps poor the fluid at different angles and harder to reach places. However, I would recommend spending a few bucks to pick up a gear oil pump rather than trying to mangle the bottle into place. I didn't follow my own advice, but it would've been much easier if I'd picked one up. You can make it work without one, but it's a little bit of an ordeal. 


Motul Gear 300 has been in the car for about 300 miles now, and so far so good. Immediately after the change, gear changes did feel minorly more smooth and positive. Had the old fluid been in worse shape, the difference would've been far more noticeable, but even so, everything feels nice. 

It should be noted that the Gear 300 fluid doesn't like being cold. I changed the fluid during a Chicago February with temps hovering between 10-20 degrees, and for the first few minutes of driving the car really doesn't like going into first unless it's at a dead stop. Changes into second and third with cold fluid don't grind, but it's not smooth either. Once some heat gets into the gear oil everything smooths right out. 

For the first 100 or so miles with the windows up and radio off I could detect a hint of gear noise that I hadn't noticed with the stock transmission and differential fluid, but that's gone away.

Overall, Motul Gear 300 seems to be a solid choice. No autocross time has been seen yet with the new fluid, but I'll be sure to post an update if there's anything notable after the season gets started. 


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