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
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
