Changing Gearbox Oil
By Grant Draper
Motocross bikes get a hammering at the best of times, whether you bother to use the clutch or not when changing gear is irrelevant, your gearbox gets a hammering too. Replacing gearbox oil on your bike is an essential part of motocross maintenance.
The best way to keep your gearbox fresh is to keep the gearbox oil topped up to the right level and in prime condition eg: replace it on a regular basis. Consistently completing this part of motocross maintenance will keep all the gearbox components in good condition so it won't just function correctly, but it will last longer too.
Each bike is slightly different, so it's always good to check your manual. Most two strokes these days are using lightweight gear oil; anything thicker tends to hamper the function of the clutch. Four strokes tend to use a multipurpose oil which is used for both the gearbox and engine, so this is even more essential to keep up, as the mechanical life of your bike is banking on you keeping up with your motocross maintenance!
I see a lot of people suggesting to change the gearbox oil every 2-5 rides, which actually means anything, after all, some of us are doing 3 hour endurance events, while others are doing 10 minute motocross races!
What I would see is pick what you think is right for you, if you drop the oil from the gearbox and its looking slightly rough, change it more regularly, as it should come out looking fairly fresh otherwise your not giving your gearbox the protection it needs.
Important !
Do not over fill when replacing the gearbox oil, this can blow seals all over the place and cost a lot of money. If you don't have an oil level window, then use a specific measuring jug. If you do have a measuring window on your crankcase, then us it, make sure the bike is upright and that you allow the oil 5-10 minutes to settle.
If you find metal shavings in the gearbox oil the first time you replace it, this might be because it has not been done regularly. Replace the oil again after your next ride; if it still shows signs of metal shavings, it might be best to refer to a mechanic.
