Mobil 1 Synthetic LV ATF HP Automatic Transmission Fluid, 1 Quart

If your transmission calls for DEXRON HP, this is the fluid that meets that spec without paying dealer-counter prices for a branded quart. Mobil 1 Synthetic LV ATF HP is a full-synthetic, low-viscosity automatic transmission fluid built for the newer GM units that run thinner fluid for fuel economy and faster, cleaner shifts. It is warranty approved for every vehicle that specifies DEXRON HP, so you can top off or do a full fill-and-drive service knowing you are not voiding anything.

The reason to run a synthetic here is what happens when the fluid gets hot. A converter locked up in stop-and-go traffic or a loaded truck pulling a grade cooks transmission fluid harder than most people realize, and a conventional ATF starts to oxidize and thin out. This one holds its viscosity under heat and shear, keeps its friction characteristics stable so the clutches keep grabbing the same way at 200 degrees as they did cold, and resists the varnish that gums up valve bodies and sticks solenoids over time. That last part is what actually kills a lot of high-mile automatics, so a clean-running fluid earns its keep.

Cold-weather performance is the other half of the story. It stays fluid down to roughly minus 61 C, which means the pump gets real lubrication to the clutches the moment you start a cold engine instead of pushing thick fluid for the first minute. Sold as a single one-quart bottle, so you can buy exactly what a top-off needs or stack up enough quarts to do a complete service. Always confirm your vehicle actually specifies DEXRON HP before you fill, since low-viscosity fluid is not a substitute for an older DEXRON VI or Mercon application.