Spring is the right time to go through your GM truck top to bottom — and if you're spending a Saturday on it, do the drivetrain and the exterior in the same session. Here's how I run through it on a Silverado, Sierra, or Tahoe coming out of a hard winter. Transmission fluid check: With the engine warm and the truck in Park on level ground, check the ATF level and condition. On the 6L80, pull the dipstick and look at the color — it should be a clear reddish tone, not brown, not black. Smell it. Burnt ATF has a distinct sharp odor that's unmistakable once you've been around it. Dark fluid past 40,000 miles with no service means a pan drop is due. On the 8L90, which uses a fill plug instead of a dipstick on many configurations, you check fluid level at the fill port with the transmission at operating temp. Dark or burnt Dexron VI means a drain-and-fill before towing season starts.
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Dexron VI ATF
SearchThe correct service fluid for 6L80, 8L90, 4L60E, and 4L80E applications. If your spring ATF check shows dark, degraded fluid, a drain-and-fill is the right call before towing season. Pick up at least 6 quarts for a 6L80 pan drop. Dexron VI is backward-compatible with Dexron III for older units as well.
Check Prices & ReviewsChemical Guys 10-Piece Car Wash Kit
$99.99Everything you need for a proper spring decontamination wash on a GM truck. Includes pH-neutral car wash soap, microfiber wash mitt, drying towels, detailing spray, and applicator pads. Well-suited to full-size truck panel sizes and the flat hood and roof sections where road salt accumulates heaviest over a Midwest winter.
Check Prices & ReviewsBlueDriver OBD2 Bluetooth Scanner
$89.95The spring scan is not optional if you're about to put a trailer behind this truck. BlueDriver reads GM-enhanced transmission codes and live TFT data — the two things that tell you whether your 6L80 or 8L90 is ready for a summer of towing or whether there's a developing issue that becomes an expensive roadside problem in July.
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