Hot Shot's Secret Green Diamond ULV ATF, 1 Gallon

Ford's 10R80 and GM's 10L80 ten-speed automatics were calibrated around an ultra-low-viscosity fluid, and they are unforgiving about it. Run a thicker DEXRON VI or Mercon LV in one of these boxes and you get exactly the symptoms owners complain about: torque-converter lockup that cycles in and out like a rumble strip, a light-throttle shudder, and slow, clunky shifts until it warms. Green Diamond ULV is a 100 percent synthetic Group III fluid built to the DEXRON ULV and MERCON ULV specs those transmissions actually call for.

It covers the trucks and SUVs running the 10-speed: Ford F-150 and Expedition with the 10R80 behind the 3.5 EcoBoost and 5.0, plus GM Silverado 1500, Sierra 1500, Tahoe, Yukon, and Escalade on the 10L80. It also fits the diesel 10-speeds, including 3.0 Duramax and 6.7 Power Stroke applications that spec a ULV ATF. Confirm your owner's manual calls for an ultra-low-viscosity fluid before you fill — do not put this in a transmission that wants standard DEXRON VI or Mercon LV.

The FR3 friction additive holds shift feel and torque-converter clutch engagement steady as the fluid heats, and the full-synthetic base resists the oxidation and shear that shorten drain intervals. A drain-and-fill on a 10-speed typically pulls 7 to 9 quarts, so one gallon covers a standard pan-drop service; a full fluid exchange, or a truck running a deep aftermarket pan, can take two gallons or more.