Flushing my transmission, or flushing money down the toilet?

Hey Zahntech --

I went to a quick lube place and they said I needed my transmission flushed. What does that mean and why do I need it?

--Flushed with confusion

Hey Flushed --

Your automatic transmission has tiny passageways for fluid to flow through. If the fluid is not kept clean, these passageways can become clogged and then you can have serious transmission issues.

Automatic trasmissions hold from eight to 16 quarts, depending on the vehicle. If you just drain the fluid pan and refill it, you only change three to four quarts of this fluid, because most of the fluid is held in the tourque converter assembly. If you attach a flushing machine, you can push out all of the fluid and put all new fluid in.

Now these quick lube places seem to tell everybody that comes in they need a flush. That's likely because they need to pay for their transmission flushing machines! I generally recommend a drain and refill every 30,000 miles and a full flush every 60,000 miles.

If you think you're having transmission problems, sometimes a flush can help. Unfortunately, sometimes the symptoms that make you think you've got an issue are indeed symptoms of a bigger problem. Automotive repair facilities (but not necessarily quick lube joints) are equipped to make that call. I say not necessarily quick lube businesses because they may or may not have certified master technicians on staff - the skills required to change oil are a subset of those required to diagnose and repair all sorts of vehicle problems.

Hope that helps!

--Zahntech