My car has 135,000 miles on it. As far as I know, the transmission is in good working order. The owner's manual doesn't have any recommended maintenance for the transmission. It says that it is optional to change the oil after 100,000 miles. I like to do maintenance/repair on my car for fun, and for peace of mind. Would it be worth it to buy some high quality transmission oil? What else could I do for the transmission (as preventative maintenance)?
If you follow the manufacturer recommended intervals and fluid specifications you will maximize the life of the vehicle. When a transmission does not have a service or change interval listed it, usually means it is a lifetime fluid. Changing out a lifetime fluid with the manufacturer specified fluid may even add additional life to the component, especially since you are following the manufacturer recommended specification of performing an optional change after the 100,000 mile mark.
When you drain the fluid, make sure you keep a sample to inspect the fluid condition and refill it only with a manufacturer approved fluid. If you have any questions or concerns you may want to enlist the help of a professional mechanic to assist you in the transmission service.
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