Diagnostic Guide

How Much Transmission Fluid Do I Need?

Refill capacity depends on the transmission and on whether you are just doing a pan drop or a full overhaul. Here is the capacity reference for the most common transmissions in service today.

4L60E / 4L65E (GM)

Pan drop: 5 quarts of Dexron VI.
Full overhaul: 11-12 quarts.
Total capacity: 13 quarts including converter.
Dexron VI ONLY. Dexron III is obsolete and Dexron VI is the only currently approved spec.

4L80E / 4L85E (GM HD)

Pan drop: 7 quarts of Dexron VI.
Full overhaul: 13-14 quarts.
Total capacity: 16-17 quarts including converter.
Dexron VI ONLY.

6L80 / 6L90 (GM 6-speed)

Pan drop: 7-8 quarts of Dexron VI.
Full overhaul: 11-12 quarts.
Total capacity: 14-16 quarts including converter.
Dexron VI for 6L80, 6L90. 8L90 takes Dexron HP (different spec, NOT interchangeable).

68RFE (Dodge Cummins)

Pan drop: 6 quarts of ATF+4.
Full overhaul: 14-15 quarts.
Total capacity: 18-19 quarts including converter and cooler.
ATF+4 ONLY. No substitutes — using any other fluid causes immediate failure.

Ford 6R80 / 10R80

Pan drop: 5-6 quarts of Mercon LV (6R80) or Mercon ULV (10R80).
Full overhaul: 11-12 quarts.
Total capacity: 13-14 quarts including converter.
6R80 takes Mercon LV. 10R80 takes Mercon ULV — DIFFERENT spec, not interchangeable.

Allison 1000 / 2000

Pan drop: 7-8 quarts of TES-295 or TES-668.
Full overhaul: 22-26 quarts depending on cooler size.
Total capacity: 28-32 quarts.
Allison-spec fluid ONLY. Standard Dexron VI can be used in emergency but TES-668 is the correct long-term spec.

Service tip

On EVERY transmission, OVERFILLING is as bad as underfilling. Check level with engine running and transmission at operating temperature per OEM procedure. Cold-checking the dipstick (or fill plug) gives you a false reading.

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