Should I drain old fluid before adding Trans Tune as a flush? [SOLVED]

Hello, I bought a 2004 Chevy 2500hd with 200,000 miles. Snow plow work truck. The transmission fluid is dark and the transmission hesitates to shift 1st and 2nd gear. Should I drain the old fluid first and refill with new fluid along with Trans Tune to act as “flush”? Then drive a couple thousand mile and then drain and refill Trans Tune as a “conditioner”? Thank you!

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Jim D.
8 months ago

Good question. Before anything else, I’d add a full can of Trans Tune and drive for 20-30 miles, then perform a drain and fill. Replace the transmission filter at this time as well.

With your fresh fluid, add a half can of Trans Tune. Drive it for 400-500 miles and perform a drain and fill again. With the fresh fluid, add the second half of the can of Trans Tune.