Complete vs. Incomplete Change of Transmission Fluid

[I’m sure someone has posted and answered on this topic, but I can’t access the search function. :rolleyes: ]

My understanding of automatic transmission fluid is that it’s important to change the stuff every, say, 45,000-60,000 miles. In the old days–that is, prior to about 2002–a technician would drop the entire pan, empty the old fluid, replace/clean the metal screen, and you’d be good to go. It was a fast procedure, if incomplete, as a good half of the old fluid remained untoched in the torque converter.

Today, by contrast, technicians provide a $99-$119 service that they advertize as replacing almost every single drop of the old stuff and replacing it with new. Problem is, they don’t open the pan, meaning that the old transmission filter/metal screen never gets serviced.

My Avalon has 105,000 miles on it and, um, I’ve never had the tranny fluid changed. (Try not to burn me on that oversight, folks.) I know I need the service, but also suspect the metal filter needs to be changed or cleaned. The guys at Jiffy Lube say they don’t do that old-school stuff anymore.

Any fact-based suggestions? Should I assume the metal filter is chalk full of metal shavings and needs to be replaced or cleaned?

I think you have to ask to have the filters changed. A lot has changed in automatic transmissions and maybe filters don’t need changing any more. For example, it used to be a routine maintenace to tighten the bands - not any more. And I not sure the fluid in the torque converter was changed, even in the old days.

“And I not sure …” English is my native language, honest to God.

30,000 miles is a more typical automatic transmission fluid service interval, although some very recent models have longer (or indefinite) recommendations.

Neither the traditional service nor the flush service is perfect, as you have observed. When keeping to the 30,000 mile schedule, I think the most sensible approach is to alternate the two types of services (flush at 30K, filter at 60K, etc.).

In your case, I would recommend the traditional service because of the mileage on the filter. You might consider a follow-up of just changing the fluid – the Avalon almost certainly has a drain plug in the pan, so it can simply be drained and refilled. This second fluid change would result in having a significant majority of fresh fluid, at noticeably less expense than doing a complete flush.

If you are the least bit mechanically inclined it’s not hard to do it yourself. Buy a repair manual for your car, Chiltons and Haynes publish great manuals, and follow the instructions within.

Reeder

  • If you are the least bit mechanically inclined it’s not hard to do it yourself. Buy a repair manual for your car, Chiltons and Haynes publish great manuals, and follow the instructions within.*

My two concerns with this are that it’s hard to reach the pan (I don’t trust jack stands enough) and I’ve heard the pan is usually topped off with fluid, meaning that it’s easy to spill the stuff on a garage floor.

True?

Some imports (as GaryT noted) have a drain plug on the pan. You can drain that first and then remove the pan. They also make drain pan “extenders” for this particular job (so it doesn’t spill out over the edges of the usual drain pan).

I agree with GaryT. At that excessive mileage without servicing I would have the filter replaced…then perhaps 12K later you can get the trans fluid flushed.

[http://www.autolifts.com/shop/media/AutoDrainpan.gif](A picture of the trans drain pan.) This is placed over a typical oil drain pan, which is smaller.

whoops! :stuck_out_tongue:

A picture of the trans drain pan.

My car has 127000 miles on it, and unfortunately I’ve not had the transmission fluid changed either (I’ve been meaning to for a while now – really). Anyway, I took it to a transmission place to get it changed, and he had some strange recommendations. After doing a littlle test drive going through neighborhoods and on the highway, we got back and he looked at the dipstick, and concluded that although the fluid was the wrong color (brown), it “didn’t smell burnt”. He stated that the transmission seemed to be working fine, and that he recommended that I NOT change the fluid. His reasoning was that the transmission seemed to be working fine, and that adding new transmission fluid with the detergents would adversely affect the seals (leakage I presume). Does that make sense to anyone else? Is he just anticipating a major failure that he can charge much more instead of doing the preventative maintenence? Should I just go ahead and get it changed?

GES

I have always heard that old fluid should not be changed.

I believe it is more a function of one that never bothered to service the trans, then notices the trans does not shift right or feels different, (problem already exists), then goes in for service hoping the ignored trans gets better.

The problem that originally prompted a trans service, to the trans that was never cared for, now gets worse and the thousand plus dollar repair gets blamed on that damn fluid change.

It was just last year that I heard a more plausible reason to not do the old fluid change. Fresh fluid does not seem like something that would harm seals but the cleaners in the fresh fluid may start to move some of junk in the trans that the old fluid was not strong enough to loosen up. Now this junk starts to mess with the valve body.

OP, I say conventional oil/filter change as Gary mentioned. With a drain plug it is easy - without a drain plug it is easy. Just use the Top Side Oil Changer to drain the pan first. I believe the entire fluid change with no filter change is just an easy money maker to the shop. Easy for the mechanic and more $$$ for the shop.

If the pump is not turning, the valves in the valve body are not moving, the trans is not shifting - so accumulators are not working, and the lock up mechanism is not operating, I do not know how all or even most of the fluid that does not get changed in a regular change, gets changed. The only benefit seems to be that the lines and cooler get flushed.

This is a gray area situation. Typically, as transmission fluid deteriorates it goes from pinkish red to dark red to orange to yellow to brown to black, with an increasingly acrid burnt smell. If the fluid is black, changing it will often “push it over the edge.” It’s not unusual to drive a car into the shop with black fluid, do the change, and then find that it won’t drive out – overhaul time. If the fluid is light to medium brown with no burnt smell, changing it probably won’t have this result. But not having examined it personally, I don’t want to say it’s definitely safe to change it.

Totally dead in the water? I have know them to go bad soon after but not to have then not move again - unless it was due to some slacker burning it up in gear before full fluid pressure was available because the car had drained over the weekend and having the VB open and apart.

It doesn’t happen every time, but it has happened.