ACDelco 10-9241 Dexron III (H) Automatic Transmission Fluid 1 Gallon

This is ACDelco Gold 10-9241 (GM part 88865545), a Dexron III (H) automatic transmission fluid sold by the gallon. It matters because the transmissions this store is built around, the TH350, TH400, 700R4, 4L60, and the early 4L60E and 4L80E units, were all engineered around a Dexron II/III viscosity. When GM moved to the thinner, lower-viscosity Dexron VI in the mid-2000s, they called it backward compatible, but a lot of builders and owners of older units still run a true Dexron III (H) fluid for the film thickness and clutch feel the original valve body and clutch packs were calibrated for.

Dexron III (H) is the last friction-modified, licensed version of the Dexron III family. It carries the friction characteristics those older clutch packs and the lock-up converter clutch were designed to see, which is what keeps shifts firm without shudder and keeps a worn 700R4 or 4L60E from flaring on the 1-2 and 2-3 changes the way a too-thin fluid can. It is also a common service fill for older Ford units that call for Mercon, and for GM power steering systems and many hydraulic applications that spec Dexron.

Use it for a pan-drop-and-filter service or a full flush on any older GM automatic, a manual transmission or transfer case that specifies Dexron III, or as the assembly and fill fluid when you rebuild one of these units. One gallon covers a typical pan-and-filter change on a 4L60E or 700R4; a full converter-and-cooler flush on those units takes closer to three to four gallons. If your transmission specifically calls for Dexron VI or a low-viscosity fluid, use that instead; this is for the applications that were built for Dexron III.