Is it really important to change the transmission fluid? Every time I get my oil changed the fast lube place wants to flush out the transmission fluid. They claim that this is superior to going to the station and having the gasket and filter replaced as well. What do mechanical types think? If the fluid doesn’t taste burnt is it OK? Is just flush satisfactory, or should the gasket and filter be changed as well?
Bah! Don’t trust em. While it’s generally good practice to change the fluid before it starts smelling like burnt chocolate, what they’re recommending isn’t as good as draining and changing at the prescribed time, or maybe even a bit before, depending on your driving habits. I’d be worried about the filter if it was drained, it may be possible that this practice might actually introduce more contaminants into the system. With a tranny, that is a very bad thing.
A general recommendation that applies to most cars is to service the automatic transmission every 30,000 miles, or 2-3 years for most drivers, as preventive maintenance. A lot of rebuilders in transmission shops, who spend all day seeing the effects of badly deteriorated fluid, service their cars twice as often as that. Unfortunately, most of the personnel at quick-lube joints are trained to sell, and often recommend tranny services, air filters, etc., much more often than needed (sometimes every visit!).
Hard use–mountain driving and trailer towing–breaks the fluid down sooner and calls for more frequent service. With this type of use, the addition of a separate transmission cooler is also a good idea.
You can always find anecdotal evidence of folks who service their transmission regularly yet still have a premature failure, and of folks who never service it and it lasts much longer than average. Still, I think it’s fair to say that any given transmission is going to last longer if it’s serviced regularly than if it isn’t.
Neither servicing method is the perfect answer. The traditional method yields a new filter and new pan gasket, but only replaces 1/2-2/3 of the fluid. The flushing method replaces all of the fluid, but doesn’t address the filter. My suggestion would be to alternate them–a traditional service this time, a flush next time (or, if cost is no object, do both at the same time).
Fresh fluid has a pink/red color and a somewhat sweet odor. As it deteriorates, it gets a progressively burnt smell, and the color goes to dull darkish red, then orange, then yellow, then brown, then black. Dark red is well due for change, the other colors indicate it’s overdue. (If the fluid is black, it’s probably best to wait until it dies, as servicing then may push the significantly worn innards over the edge to failure.) The ideal is to service it before the fluid breaks down.
After a traditional service, it’s harder to judge by fluid inspection, as the remaining old fluid will sometimes give the dark red appearance to the whole mix. It’s most helpful to combine knowledge of the car’s service history and typical usage with fluid inspection to judge when to recommend servicing.
YOu can buy a whole lot of fluid for what one transmission costs. For most drivers, most cars 30-40K miles is a good service interval.
When you drain your transmission fluid there is a lot of it left in the torque converter, the flushing is to get this out as well as what is in the pan. Any time the pan is removed a new gasket has to be installed.
On the transmission pan of my Ford van it says “This pan is equipped with a re-usable gasket.” I’ve changed the fluid 3 times (in 80,000 miles) and the gasket is still going strong.
You got me there Xema, sorry if I misled anybody.
I note that it seems impossible to buy a transmission filter by itself – a gasket is always included. I save them as decoration.
If you’re going to get into doing transmission fluid and filter changes, I’d recommend installing a drain plug – makes the job less messy.