Weird question, but I figured this is probably the best place on the internet to ask! I've come into possession of an electric vehicle conversion based upon a recent-model Hyundai Getz which is a front-engine, front-wheel-drive compact car. I'd like to change the fluids since I'm not sure about the quality of the fluids already in there, however I have no idea what would be best to put in it. There's a noticeable performance difference between when the car is cold vs warm, which I attribute to the oils thinning out as they heat up - but without the heat of a petrol engine, that takes a while on this car. Anything I can do to reduce friction is great because it means more range. Keep in mind I'm in Australia for availability, but oil price is almost not a concern since it impacts range & I'll import the good stuff if I have to. I'm not a mechanic but because this is such a unique vehicle I wouldn't expect my local mechanic to know what's best for this car. Can provide photos if it would help. Transmission: this is a manual transmission but not the stock one and I have no idea where it came from. The clutch plate has been removed; the only way to change gears is when the car is stopped (you can take off from 3rd gear without issues so this isn't a problem for normal driving). This also means we spend 99.9% of our time sitting in 2nd gear, and I don't know how this will go over long-term with regards to wear levels. The transmission mates directly to the electric motor & gets a bit of heat from the motor, but constant thickness over a wide temperature range would be great to help those early morning winter starts. I'm honestly not even sure what type, thickness or quantity of oil is currently in there. Should I bother trying to get it tested, and anyone have any leads on suitable testing places within Australia? Given there's no clutch plate would a different type of oil, maybe an ATF, be better? Anyone have any recommendations about what weights I should be looking for, or even a specific brand of oil given I need the most consistent thickness over the widest temperature range that I can get? Diff: This looks stock. Since this gets almost no heat other than what it generates itself through internal friction, I'm pretty sure swapping this with something better will improve my range. What's some options for the best synthetic diff oil that's slick at lower temperatures? And finally - anyone have any idea how frequently I should be changing these oils? Because of the potentially increased wear levels I'm expecting by always staying in the same gear, I'm thinking I might just change the trans oil every 3 years/5000mi. Diff oil is probably fine for the normal schedule.