We are dropping the lower unit on our Mercury OptiMax to install a new impeller and new gaskets. We also give step by step instruction on how to change the g In automatic transmissions, the suggested service interval is about every 30,000 miles or 30 months. You must change the automatic transmission fluid sooner if the dipstick reveals a dark or burnt-smelling fluid. Find gearbox specialists near you. We can help you find local gearbox oil change specialist garages. If you have identified that your If you change your transmission oil, you should also replace the filter to make sure that any remaining particles are filtered out. Common Castrol gear oil types are 75W90, 80W90, and 75W140 for automatic transmissions. You need to find out which oils are approved and which one is currently in your vehicle. Start the engine. Shift the gear selector into the corresponding mode – “Park” or “Neutral”. Unscrew the inspection plug at the bottom of the gearbox. If the fluid leaks out of the hole, there is no need to top it up. Screw the cap back in. If nothing leaks out, this means there isn’t enough oil. First Name:Gareth. Toyota Model: 2005 Corolla T-Sport. Toyota Year: 2005. Location: Yorkshire. Posted October 20, 2010. it probably doesnt need changing. changed mine at 60,000 miles, never been done before, but did it as its a relatively cheap and easy job to do, and its not going to harm it changing the oil. Proceed as follows: 1- Top mount gearbox oil refill plug: Add the exact quantity of gear oil (transmission fluid), as given in your car manual. Use the recommended gearbox and differential lube but almost all manual transmission require 75W90 or 80W90 gear oil, which can be either mineral, semi-synthetic or synthetic like for engine oil. . 2 The oil needs to be changed every 30,000 to 50,000 miles, unless your owner’s manual states otherwise. The differential is a part in your vehicle that compensates for the difference the inner wheel and the outer wheels travel when you turn a corner. If you have a rear-wheel drive vehicle, your differential will be in the back with its own Although, when I enquired at the local dealership they said that it should be done about every 40k miles (and uses 7-8 litres of oil). Strange ! They also recommended that I use Castrol Dexron III because it's what they use. My car has done about 103k miles so I guess I can hold for about another 10-15k miles. GmJMQ0.