Originally Posted by judgemikdredd
if it doesnt look burnt i wouldnt do it period
Why not? GM recommendation is to change it every 100,000 miles, isn't it?
And I've heard the opposite--that if it looks/smells burnt, then don't change it, because you're just going to kill your transmission. E.g., here'* a guy of that opinion :
When not to flush:
Before draining or flushing you should pull the dip stick and look at the fluid. If it is dark, burnt smelling, and you see little flakes or speck in it, DO NOT FLUSH IT. The fluid and transmission is TOAST, but the transmission just has not figured out it should die yet. In these cases for reasons no one has figured out yet, if you flush a transmission in this condition it will fail right away. Real strange, but that is what seems to happen. If your trans is in this condition just drive it while you save for a replacement transmission. There is no way of telling when it will fail. It might be today, next week, or next year, but it is doomed.
The goal here is to flush the trans BEFORE the fluid gets rancid. What you are taking out should look like what you are putting in. Do not wait for a color or smell change. My 4Runner Owner'* Manual calls for transmission fluid change at 30,000 mile intervals. The industry standard it two years OR 24,000 miles which ever comes first. It is your truck, you decide what is best for you.
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