When should I change my transmission fluid?
Great question! I’m going to assume you’re asking about an automatic transmission. The answer is: it depends! I suggest starting by looking at the manufacturer’s schedule of maintenance recommended for your particular vehicle in the owner’s manual. Between 30,000-60,000 miles is a common interval to replace transmission fluid. That advice is good to follow for a long, healthy life for your transmission.
Some manufacturers build automatic transmissions now with no dipstick, stating that the transmission is sealed for life and requires no fluid replacement. Although this sounds good, it isn’t a good way to make the transmission last a long time. The manufacturer’s main concern is that the vehicle make it past the time and mileage specified in their warranty.
The exception to this recommendation is when the car has over 100,000 miles on the original transmission fluid, or the current transmission fluid is very dark and burnt. Changing the fluid in either of these scenarios can very likely do more harm than good, because the transmission has adapted over time to operating on dirty fluid with worn clutch plate material in it, and suddenly replacing that fluid with new fluid can cause it to shift poorly and slip while accelerating. Approach either of these situations with caution.
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