I see the need for a thread like this, simply because of the overall confusion over this topic.
Pan drops and a total flush comes down to logic.
Pan drops:
If the fluid is brown and you don’t know its history, to me it’s not worth taking the chance of going from a working trans. to dead one.
If the fluid is burnt and brown DON'T flush it, just drop the pan and add 8 new quarts, down the road 5 to 10,000 miles later you could drop the pan; again and replace another 8 quarts. A pan drop will do nothing but help. Do not get worried, that is recommended service, a full flush is 50/50 work/destroy.
Trans. Flush:
From what I’ve been told is that if the trans has had regular service in the past it will be ok to do a full flush, (at least a pan drop every 50,000 miles.)
When the fluid is good its real red or pinkish, it has a smell but not like when its burnt, to make sure compare to a friends or family's cars trans fluid.
If it’s at ~100,000 miles and never had anything done (not even a pan drop), if the fluid is brown and stinks like its burnt, dont flush just do a pan drop, its safer.
If you get it flushed, make sure to give your mechanic EXPRESS instructions to follow GM procedure to a T; which means NO solvents, just Dexron. Nothing but Dexron. Ever.
Synthetics:
If you DO know the history of your transmission, or if your fluid is still red, and you can do full flushes on your transmission, then a switch to synthetic is recommended. ONLY IF your transmission is in perfect, or close to perfect condition.
Anything else, will result in imminent failure of your trans. if you convert from dex fluid to synthetic fluid such as Amsoil.
Is synthetic better for your car in your engine and transmission yes. but if your transmission is not in great condition, then just stick to either pan drops or flushes.
On the other hand, if you have a brand new transmission, then by all means, make the swap.
I hope this helps some of the confusion.
