Some info on automatic transmission service

[CharlesW]

In the recent thread about oil change ramps/jackstands, we had some discussion about flushing automatic transmissions when changing the fluid.
It was mentioned that Honda had put out a service bulletin advising against it. I finally got around to visiting with my mechanic that I have a lot of faith in. He may not know it all, but he doesn`t claim to. What he does know always impresses me.
Anyway, some of his comments.
1. Several automatic transmissions have filters that are not normally changed during a routine fluid change. Imports as a general rule.
2. Their shop does not use a flushing pump. They use the automatic transmission itself to pump fluid through the transmission and torque convertor. All their pump does is maintain a supply of fluid to the transmission pump.
3. On my vehicles, (GM), they remove the pan, pump fresh fluid through the torque convertor, replace the filter, replace the pan and fill the transmission with fresh fluid.
4. Evidently, some places do a flush with an actual flushing pump without removing the pan or replacing the filter.
5. They feel that on any vehicle that has a changeable filter, it should be replaced.
6. They also feel that removing/changing the fluid in the torque convertor is well worth the effort. Just dropping the pan and changing the filter does not do that.
7. His personal opinion on change intervals for most drivers, no towing or abuse, is that 50,000 miles is fine.
8. He feels that synthetic oil is well worth the extra cost in an engine, but is not yet convinced it is worth it in an automatic transmission. He does say that if your car came with it, he would continue to use it. If your vehicle did not come with synthetic transmission fluid, he doesn`t think it is necessary to switch to the synthetic.
9. He also says that while the manufacturers of the synthetic transmission fluid don`t recommend using it in older vehicles, he can`t think of any reason not to if you want to switch to the synthetic.

He probably said more, but I can`t remember and besides, I`m tired of typing.

Charles

[belcherm58]

I have a Toyota Tacoma 4x4. I had the transmission flushed at 50K at the dealer. I wanted to have the filter changed and he service rep said it was not nessasary as it was just a fine mesh screen and would be flushed clean when they reverse flush. They also said that they put seal conditioners in the flush with some solvents and fill with clean fluid. I had a coupon and got
it done for $89.95. I noticed right off crisp firm upshifts and downshifts.
I do a little towing also. The rep said doing this every 50K would insure long transmission life. I use synthetic oil in the engine and plain dino based products everywhere else. I am as anal about maintenance as I am detailing.

[Dozerboy]

I run synthetic everything, but motor oil for now. A synthetic transmission fluid will help keep heat down and well help the tranny last a long time. I just drop the pan on my truck its better to do the TC too, but I don`t know about it really being "worth the effort". I also have 2 tranny filters on my truck the external one needs changing every 10K.

[BenjiBoy650]

Here`s the Service News where Honda says not to use flush systems, on page 4.

Page 4

You can get all the fluid out of the tranny if you do it a little at a time...drain, refill, drive, drain, refill, drive, etc for about 4 or 5 times. You won`t get all of the old stuff out of course (if you keep diluting you only get so far - 50%, then 25%, then 12.5%, then 7.5%, etc) but you`ll get most of it out and you can do this all yourself.

Re: filters, at least on the boards that I frequent, the filters have just recently come to light. It`s not common practice to replace them on Accords yet, but it has been catching on. Mostly the thing that stops people the most is that it`s still no widespread knowledge where exactly the filters are for both the I4 and V6 tranny, and their part numbers.

Synthetic oil I think is probably a no-no at least in Honda`s. Their trannies are very picky and fragile and I wouldn`t be giving them a chance to deny a warranty claim. Also for Honda, I think their tranny is too fragile for 50K intervals. Our 97 Camry has had little to no tranny maintenance and it`s still running strong at 185K miles, but the Honda trannies have been crap lately. If I had a Honda auto I would be changing their fluid at 10-20K depending on the chassis and engine they`re mounted to. People don`t know that they don`t get all the fluid out at once, so doing it at 50K DIY for them might be risky.

Sorry for all this Honda-specific stuff, I know this is a forum for all cars but that just happens to be my knowledgeable area.