Playing with fire or being prudent?

August 21, 2011 10:09 AM

CarFilter: Mess with the automatic transmission fluid or not? Difficulty? 2003 Ford Explorer with about 105,000 miles and a "sealed" automatic transmission.

I own a 2003 Ford Explorer (like the '02, the not-quite-related-to-every-other-Explorer model). My usual mechanic says that I should have the transmission fluid checked or flushed. The problem is that, apparently, only a Ford dealer can do this because there's no dipstick. According to my Haynes book, Ford considers the transmission in this vehicle to be a "sealed system" that doesn't need regular service. The vehicle also has 105,000 miles, though I've only owned it for the last 35,000 miles. Compounding my confusion is the old saw that says "if you haven't had a transmission regularly serviced at 20k intervals, don't touch it unless it dies."

So, hive mind, should I take this Explorer to a Ford dealer and have them poke at the fluid, or should I just leave it alone since the transmission is working?

posted by fireoyster to travel & transportation (7 answers total)

How handy are you with a wrench? 'cause those transmissions do, in fact, have a combo two-piece drain/fill plug on the bottom. Slightly loosen drain plug, let some drip on finger, examine fluid.

Draining and re-filling it isn't, I'm told, rocket science. Using the right transmission fluid apparently is: be sure to use the exact Ford-branded Mercon Whatever that it calls for.
posted by introp at 10:21 AM on August 21, 2011

For the record, I don't know that I agree with the old saw about not maintaining a transmission unless it's been serviced in the past. I think that's hand-waving based on people's reluctance to touch a high-money part that rarely goes bad in a modern car until very late in the game.

However, I would suggest this. Your mechanic says that the fluid should be checked or flushed. This is based on a typical automatic tranny. Fair enough, but if the transmission is a) claimed by Ford to need no regular maintenance and b) it's running good, I think that would swing me toward the idea of not trying to do anything to it.
posted by randomkeystrike at 10:24 AM on August 21, 2011

I'm with randomkeystrike. Mostly. There is also the theory that replacing fluids cannot do any harm, and can extend the life of the unit. Ford believes it doesn't need maintenance for the life of the unit, but what is their idea of the life of the unit? 200k miles? 15 years?

I think the old saw comes from the following situations:

1- where a trans has not been maintained, is in the process of failing, someone changes the fluid and filter in an attempt to resurrect it, and then it proceeds to fail anyway.

2- where a trans is working fine, someone decides to be proactive by changing the fluid and filter, and then uses the wrong fluid, destroying the transmission.

3- someone does the same as #2 and simply botches the job. Forgets to tighten something, uses the wrong filter, the filter was bad out of the box, etc.
posted by gjc at 10:55 AM on August 21, 2011

4- Someone replaces the fluid, extending the life of the transmission; car owner has no need to buy a new Ford vehicle
posted by Sys Rq at 11:32 AM on August 21, 2011

(That said, I wouldn't touch it. A closed system means there's no right way to do it. That's how they get you!)
posted by Sys Rq at 11:39 AM on August 21, 2011

The old saw is that changing the fluid will dislodge loose pieces of metal that will then cause transmission damage. Don't know if it's true.
posted by zippy at 11:50 AM on August 21, 2011

My usual mechanic says that I should have the transmission fluid checked or flushed.

Why?
Are you experiencing problems with the transmission? Are you within the factory-recommended mileage for a check? If not, then leave it alone.

But, if you insist...What they will do is hook-up the diagnostic computer and run your car until the transmission (and fluid) are at a certain temperature. Then, they will get a readout of the fluid level in the transmission. If it's low, they will add more. If not, they unhook the computer and send you away, a little lighter in cash.

Compounding my confusion is the old saw that says "if you haven't had a transmission regularly serviced at 20k intervals, don't touch it unless it dies."

I've never heard that one, but it doesn't really apply to modern transmissions, especially sealed units.
posted by Thorzdad at 12:06 PM on August 21, 2011