GM Transmission service question

I have a 2000 Chevrolet Impala with 100,000 miles on it. I want to get the transmission serviced. Which service is better? Going to a quick lube and having all the transmission fluid changed out(without dropping the pan) or having the dealer service where they drop the pan replace the filter and replace the fluid that leaks out? I was told by someone that its actually not a filter any more just a screen and doesnt need changed unless you are noticing problems. I'm not.

If you are going to have a fluid and filter change on the transmission, I recommend you get a full flush of the system, not just whats in the pan. Typically less than 1/2 of the total fluid in the system is in the pan, the rest is in the lines and the torque converter. Make sure the filter is replaced and that the magnet in the transmission pan is cleaned of all the metal it has collected.

On top of burly's suggestion, make sure they clean the inside of the pan itself. Its amazing all the gunky sludge (actually its eroded clutch pack particles, dirt etc) accumulates in the pan. This must be mopped out.
Also be SURE they reinstall the little magnet inside the pan. Mechanics are notorious for just throwing these things away and not replacing them. For about $1, these magnets are very cheap insurance.

Finally, some filters just have a nylon screen, (like a bug screen on your house windows but finer), but most use a fabric (Dacron) filter. The fabric kind catches much more gunk.

Oh yes, do this service on your trans every year or two. If you start noticing problems, often its too late, and your transmission is already suffering damage from old fluid or a blocked filter.

The filter in the 4T65E is dacron, not screen. Drop pan renew filter then flush converter and cooler. Lubemart don't pull pans. I would go to a good tranny shop and tell them to do it just as I described.

Good luck

never ever flush a tranny, even if they were the last business on the planet. You would be better running the old fluid - and Im not being facetious. the flushing process with dislodge clutch material and phenol and deposit it where it does not belong.

take it to a shop that will drop the pan, clean it and drain the converter. if the converter is not tapped, have a shop drop the valve body, all fluid but 2 qts will come out - this will be enuf. and have them add a cooler in addition to what you have. This service will run $150 for regular fluid, $200 for synthetic, but sure beats $1400

I my self have been flushing transmissions for 25 years. Never has my shop had a problem. We do not service failing transmissions, trannys with "excessively" burnt/black fluid or runability complaints. EXCEPT, were the customer knows for sure the service will fix his complaints. And sometimes it does, for a few miles.

I will indeed service/flush a tranny with varnished fluid that hasn't been changed in a million miles or so. The tranny is still working correctly though.

Theres problems because of either incompetence or lack of being thorough. Not with just the service/flush but with the customer also.

Let me explain this. First off I would say, most people only want a transmission service when they feel something isn't working correct. So theres the problem right there. They already have a problem. When my shop is about to service/flush a tranny, we make sure of customer complaints then it gets a thorough road test. If it passes the tests, then service/flush with no problems. This way there is very little chance of "it didn't do that before you worked on it" statements.



Maybe we need to get the mythbusters on this LOL

stay cool

A few years back, perhaps 2, someone who worked for GM got real agro about people complaining online about the effects of Dexcool on relatively new cars. In response, in perhaps 5 minutes I had found over 900 individual references online for the week in question of people complaining about 'x' failures due to dexcool. Point being, where there is smoke there is fire. Unlike internet rumors (Bill Gates gives you a million bucks if you send an email) complaints come from single point sources: i.e. "My car broke down today due to yyyyyyy"

Ignoring the fact that no repuatable tranny shop on the planet will flush a tranny (and why not, the flush service costs more than a pan drop and takes less labor) lettuce consider:

You will hear complaints like the following:

"My transmission died". And this can be backed up by 'good science' - trannys do die from normal use. But the rate of failure is actually very small. The 89-92 taurus tranny is considered one of the worst, but its worst year (91) it failed 70 per 1000 by 75K miles. Or in other words, by the time the 91 reached 5 years old appx 4200 trannys failed per year on average. Thats not a whole heckuvalot to go around..but you see how the perception runs. There is a perception tauri are to be avoided.

"I changed my fluid by droppin the pan and soon thereafter it died". There is also some good science here. IF the tranny was very worn and 'close' to failure, the re-swelling of the seals from new fluid could hasten their destruction - but mind you, this occurs typically on only very high mileage, high abuse cars and the incidence is rather low. The perception is the practice is safe and without risk.

"I had my fluid flushed by Jiffy Lube and soon thereafter it died". There is real good science behind this. According to a fairly recent issue of either Motor or ATRA magazine (within the last year) it has been noted that 3 out of 10 trannys flushed need a rebuild within 5000 miles. This is regardless of mileage, condition, age. Some people might say: "yeah but by the time you decided you need a flush, it was too late" and Im sure the liability lawyers like this. 3 outta 10. thats 300 per 1000 or 4 times the failure rate of the 91 taurus. And its mileage independant. I smell smoke.

the outlying reason is thus: People either work on their cars themselves for the maint chores, or they do not work on the cars themselves. People that do work on them tend to be 'net connected' more than people who do not. People who do not work on their cars, be it housewives, elderly, apartment dwellers - whatever - must rely on others for basic maint. Changing a tranny is basic maint and there are enuf commercials on TV that one can conclude its not a well guarded secret. Tranny shops do not flush. Jiffy Lube does, but Jiffy Lube does not repair. A damaged tranny owner will seek remedy elsewhere. Im sure they will first contact the shop owner, whose livlihood DEPENDS on selling such questionable practices, and who will give the 'yeah but it was close to failing as is' speech and NOT report failures to the general public or online.

And lo and behold, within a few minutes, any person reading this can google search and find thousands of links to incidences of trannys failing right after a flush. If we are willing to suspend reality for a few moments I guess we can conclude that people only flush trannys at the end of the service life of their car. But that also requires us ignoring the large finished lubricants market for ATF and the parts market for filter kits - including late models.

And finally getting to the nut of the problem as to why the trannys fail: flushing them, ESPECIALLY without a pan drop, stirs up the matter that WILL be in the pan or collected in areas of 'dead flow'. This matter is no longer in microscropic particle format in suspension, but has now congealed and is clumpy. It will cling to the metal particles that WILL be there. This material WILL be deposited on seals and cluthes. It WILL cause shift valves to bind. If you delay the throttle valve on a 4L60 by a few milliseconds, the tranny will fail spectacularly within a few hours of operation. (for example)

And of course, unless the flushing shop uses a chassis dyno, which they dont, they will not flush locking converters, any valve body circuits, and only a portion of the cooling circuit which is now universally thermostatically controlled.

I used to work in one of those quick change oil places and the only problems i have ever seen after a filter and flush was:
#1 the filters as so alike now that they can easily be mismatched, for instance there are 2 kits that use the same pan gasket and the identical filter the only diffrence between the 2 is the O ring that actually holds the filter in place. To make matters worse even the sevice manuals had indicated the wrong part #s
#2 many people do not invest in a deasent torque wrench and always over tighten the pan gaskets causeing the fluid to leak out, leaving you with a dry tranny! I addmit this did happen to me a few times in the past but once I got a snap-on torque wrench to replace my craftsman I never had that problem. I have personally changed over 400 tranny filters and done flushes on 90% of them (the other 10% didnt want to pay the extra cash) without a single problem besides the ones noted above!

Thanks for the advice everyone. It seems this one is hotly debated. I'll probably take it to a tranny shop and have it serviced. thanks again.