I have a new to me Chevy TrailBlazer with a lot of miles on it. It looks like the transmission fluid has never been changed.
I have had one mechanic tell me to change it ASAP or risk destroying the transmission. While another mechanic said ‘no way - after all this time changing it will loosen dirt and cause leaks and destroy the transmission’.
What should I do? I do not want to replace the transmission.
I would remove the transmission pan, drain the fluid and change the filter. Make sure the transmission is refilled with the recommended fluid. You may have to repeat the process a couple of times if the fluid is no longer red. The second mechanic is spreading an old wives tale. If a transmission is “flushed” incorrectly it can destroy a transmission.
You will get different opinions. Mine is to drop the transmission pan, clean out all the gunk in the pan, replace the filter, put it all back together and refill with the proper fluid.
I would NOT risk a transmission flush, or a machine done transmission fluid exchange. These services are common at quickie lube places which should be avoided in general and definately not where you want your transmission serviced.
The safest bet is to pay more and have a GM dealer do the service, or a good independant transmission specialty shop is a good option too. If you have a really good and trusted mechanic he can do the job also. A trans shop or dealer trans tech will be better able to look at the gunk in the pan and assess the condition of trans from what he sees.
Drop the pan. Inspect it & clean it. Replace the filter. Refill it. This will change about half the fluid. If you want to change it all, have a shop do fluid exchange - NOT a flush, and only after the pan & filter. Or just drain and refill again after 1000 miles or so.
This will not hurt anything and if anything happens soon after then it was going to happen anyway. The only thing that can go wrong is using the wrong kind of transmission fluid. So just make sure that it gets the right stuff. (Check your owner’s manual, but for most GMs - you didn’t give your year - Dexron VI is now recommended. Dexron of some type is required).
Thanks, the year is 2002. I am considering taking it to a transmission expert who offered to run diagnostic tests before doing anything else…
I think that is a completely reasonable thing to do - so long as the transmission expert is not at a national chain operation (such as AAMCO which we know means “All Automatics Must Come Out”). A local, independent shop is in order and they can put a scanner on it to see if it is behaving itself and then do the servicing if warranted.
The fluid could have been changed once or twice but ready for it next go around. Mechanics can be drama queens and alarmists.
If the trans is behaving alright now then changing the fluid won’t hurt it . Most of the horror stories are about transmissions that were on the way out and somebody thought - wrongly - that a fluid change would fix it .
The only thing holding your transmission together is the varnish…You are screwed either way… 150K miles is Prime Time for transmission failure, so start saving your money…