Time for a Transmision Flush?


Everytime I take my car for an oil change I get the “must replace the transmission fluid” talk. I have a 2001 Honda Accord. I was told by another place that in older cars you could damage the car by changing the transmission fluid. More importantly, transmission fluid does not degrade like oil, does it? Should I have it flushed?

— Candace,
Houston, Tx


Many owner’s manuals say it isn’t necessary to change your Automatic Transmission Fluid (ATF). And that’s certainly true for new vehicles. But if you’ve ever been on the receiving end of a mechanic’s bill after having a burnt-out transmission replaced, you’ll agree that it is wise to replace the ATF if you have an older or heavily-driven vehicle. Most mechanics advise that for optimum protection, change the ATF and filter every 30,000 miles (unless you have a new vehicle that is filled with Dexron III ATF which is supposed to be good for 100,000 miles).

An automatic transmission creates a lot of internal heat through friction and causes the ATF to heat up once the vehicle is in motion. The usual operating temperature for ATF is around 175 degrees F. If that temperature remains constant, ATF lasts longer — some mechanics say up to 100,000 miles. But a lot of stop/start city driving, hill or mountain driving, towing and even just living in area that has extreme elevated temperatures in summer months means the ATF temperature can rapidly fluctuate north of that recommended 175 mark, causing it to oxidize, turn brown and smell like burnt toast — meaning the life of your ATF is shortened.

According to the Automatic Transmission Rebuilders Association, 90% of ALL transmission failures are caused by overheating. And most of these can be blamed on worn out fluid that should have been replaced. With a vehicle such as your 10 year old Accord, the wiser choice may be to get the ATF changed rather than face a big bill to replace a burnt-out transmission. That said, the best under the hood advice is always to find a good mechanic whom you trust — or shop and ask around until you do.

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