Car Transmission

The fluid in your car’s transmission should be replaced every 30,000 miles. Over time, the assembly’s friction creates an enormous amount of internal heat. That causes the fluid to oxidize and lose its ability to lubricate the moving parts. Eventually, the lack of lubrication will cause the operational temperature to rise further, leading to varnish, cracked seals, and a loss in pressure. If your transmission fails, you can expect a hefty repair bill.

Below, I’ll quickly take you through the steps involved with changing your car’s transmission fluid and filter (it’s recommended that you do both at the same time). You can pay a mechanic to do the job, but you’ll save time and money by doing it yourself.

Draining The Fluid

If your car has an automatic transmission, it will also have a service pan that contains both the fluid and the filter. On the pan’s underside, there will normally a plug. Remove it and drain the fluid into a catch container. If the pan does not have a plug, you can drain the fluid when you remove the entire pan.

Removing The Transmission Pan

After completely draining the fluid, you’ll need to remove the pan. Look for bolts around the pan’s perimeter that are securing it in position, and remove them. Before removing the last two bolts, place your hand on the pan’s underside to hold it. Then, remove the remaining bolts.

Cleaning The Pan

After you have removed the pan, place it on a flat surface. Clean out the remaining fluid and look for small residual metal particles. There will usually be some, but an excessive amount can eventually cause problems within your tranny. Clean the pan as thoroughly as possible. Then, place a new gasket (included inside transmission service kits available at auto supply stores) along the rim of the pan.

Replace The Transmission Filter

In most cases, the filter will be housed inside the pan. Occasionally, you’ll find it secured with bolts to the front of the tranny. Remove it and replace the corresponding seal. It’s critical that the seal is in good condition in order to prevent fluid leaks. Replace the filter and reinstall the pan. As with the filter seal, make sure the gasket along the rim of the pan will prevent leaks.

Replenish The Fluid

At this point, your work under your vehicle is complete. Lift the hood and replenish the fluid level in the appropriate reservoir. Then, turn your car on and allow the engine to idle for two or three minutes. Check the fluid level again and add more, if necessary.

That’s it. You’ve successfully serviced your vehicle’s transmission. It’s a good idea to check the fluid level after a few days. Also, check the ground directly underneath the assembly to make sure that a badly positioned seal or gasket isn’t causing leaks.