Which Automatic Transmission Fluid (Dexron VI) Brand Wins?
In our test we compared 4 automatic transmission fluid (dexron vi) options head to head. Red Line D6 ATF came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Red Line D6 ATF
Price shown in test: $23 per quart, almost three times the price of the ACDelco
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SuperTech
Price shown in test: around $9 per quart, about a dollar more than the ACDelco
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The quick take
The short version of why each pick lands where it does, built straight from the measured results.
“The Red Line completely dominated the competition with the first place finish in every category.”
Best in 2 of 4 measurements, including Cold flow race at -40F, new fluid and Cold flow race at -40F, cooked fluid.
Best in 2 of 4 measurements, including Flow speed race, new fluid at ~70F and Flow speed race, cooked fluid at ~70F.
The measured results
Every number below is read straight from the test. Products are listed in the order they finished.
Certifications/specs
- 1Red Line D6 ATF (high performance)
recommended for GM Dexron VI applications and several others, made in USA
- 2SuperTech
full synthetic, Dexron VI, claims compatibility with both Dexron and Mercon applications, manufactured in USA
- 3Mobil
synthetic blend (the only one of the four not full synthetic), for General Motors vehicles, claims improved oxidation/thermal stability, optimized friction performance, improved anti-wear protection; made in USA
- 4ACDelco
Dexron VI, full synthetic, distributed by General Motors LLC, recommended for GM transmissions 2006 and newer but claimed backward compatible with older Dexron transmissions
Thermal breakdown/evaporation (200g heated to 410F for 2 hours)
- 1Red Line D6 ATF (high performance)
started 404.79 g, ended 397.85 g, a loss of just under 7 g, the best (least) evaporation of the four
- 2SuperTech
started 394.64 g, ended 386.3 g, a loss of 8.34 g, edging out the ACDelco by just over a gram for 2nd place
- 3Mobil
started 410.87 g, ended 390.26 g, a loss of 20.61 g, more than twice the loss of ACDelco or SuperTech and by far the worst of the four; became visibly dark and produced a lot of vapor early in the test
- 4ACDelco
started 429.88 g, ended 420.25 g, a loss of 9.63 g, the worst of the three non-Mobil fluids (3rd place among the four)
Flow speed race, new fluid at ~70F (all four)
- 1Red Line D6 ATF (high performance)
tied for 3rd place with ACDelco, all four within 1.17 to 1.22 seconds of each other
- 2SuperTech1st place
winning by less than an inch
- 3Mobil2nd place
close behind SuperTech
- 4ACDelco
tied for 3rd place with Red Line, all four within 1.17 to 1.22 seconds of each other
Flow speed race, cooked fluid at ~70F (all four)
- 1Red Line D6 ATF (high performance)2nd place
only a 1.6 percent performance loss versus new fluid, the smallest loss of the four
- 2SuperTech1st place
again; a 7.1 percent performance loss versus new fluid
- 3Mobil3rd place
a 5.4 percent performance loss versus new fluid
- 4ACDelco4th
(last) place; a 7.7 percent performance loss versus new fluid, the largest loss of the four in this specific race
Foaming resistance (5 minutes)
- 1Red Line D6 ATF (high performance)
passed, no foaming; described as performing best overall heading into this test and retaining its dark red color longer than the others under heat
- 2SuperTech
passed, no foaming for the full 5 minutes
- 3Mobil
passed, no foaming
- 4ACDelco
passed, no foaming
Cold flow race at -40F, new fluid
- 1Red Line D6 ATF (high performance)1st place
by far, 24.53 seconds, described as destroying the competition, winning by over 3 inches
- 2SuperTech
barely edged out ACDelco for 3rd place, around 34.5 seconds
- 3Mobil2nd place
at 30.16 seconds, well ahead of ACDelco and SuperTech by over 2 inches, a strong result for a synthetic blend
- 4ACDelco4th
(last) place, around 34.5 seconds, very close to SuperTech
Cold flow race at -40F, cooked fluid
- 1Red Line D6 ATF (high performance)1st place
by far, 27.37 seconds, winning by about 5 inches; only a 10.4 percent performance loss versus its own new-fluid time, the smallest loss of the four
- 2SuperTech3rd place
at 40.14 seconds, about an inch ahead of ACDelco; a 14.2 percent performance loss versus new fluid
- 3Mobil2nd place
at 39.88 seconds, though heat exposure sharply cut into its lead over ACDelco/SuperTech; a 24.4 percent performance loss versus new fluid, the largest loss of the four
- 4ACDelco4th
(last) place at 42.78 seconds; a 19 percent performance loss versus new fluid
Independent oil analysis lab report
- 1Red Line D6 ATF (high performance)
by far the most robust detergent/dispersant additive package at over 300 parts per million; by far the most robust anti-wear additive package at 2.5 times more anti-wear additives than the competition; total acid number under 2 like the others; only trace levels of wear metals (iron, tin)
- 2SuperTech
detergent/dispersant and anti-wear additive levels described as close to the same as ACDelco and Mobil (well below Red Line's); total acid number under 2 like the others
- 3Mobil
detergent/dispersant and anti-wear additive levels described as close to the same as ACDelco and SuperTech (well below Red Line's); total acid number under 2 like the others
- 4ACDelco
detergent/dispersant and anti-wear additive levels described as close to the same as SuperTech and Mobil (well below Red Line's); total acid number under 2 like the others
All measurements (3 more)+
Lubricity/wear scar test vs ACDelco
- 2SuperTech
wear scar of 8.44 mm, about 5 percent more damage/larger than the ACDelco's; lost this pairing to ACDelco and finished 4th (last) overall on wear resistance
- 3Mobil
tied precisely with ACDelco for the same size wear scar, described by the narrator as the first time this exact tie has happened in his lubricant testing; tied for 2nd place overall on wear resistance
- 1Red Line D6 ATF (high performance)not tested
- 4ACDelconot tested
Lubricity/wear scar test
- 1Red Line D6 ATF (high performance)
the smallest wear scar of the four, though by less than 1 percent smaller than the ACDelco/Mobil tie; declared the best for wear resistance, finished 1st
- 2SuperTechnot tested
- 3Mobilnot tested
- 4ACDelconot tested
Lubricity/wear scar test vs SuperTech
- 4ACDelco
wear scar of about 8 mm, smaller than SuperTech's 8.44 mm, winning this pairing; tied with Mobil for 2nd place overall on wear resistance
- 1Red Line D6 ATF (high performance)not tested
- 2SuperTechnot tested
- 3Mobilnot tested
How it was tested
- thermal breakdown/evaporation (Noack-style): 200g of fluid heated to 410F for 2 hours, weighed before and after (run as two pairs: ACDelco vs SuperTech, then Mobil vs Red Line)
- lubricity/wear scar test using heat-exposed (cooked) fluid on a lubricity tester (same two pairs)
- flow speed race at approximately 70F, all four fluids simultaneously, both new and heat-exposed (cooked) fluid
- foaming resistance: fluid shaken and observed for bubble formation over 5 minutes
- cold flow race at -40F in a freezer (about 10 hours), all four fluids simultaneously, both new and heat-exposed (cooked) fluid
- independent oil analysis lab report: wear metals, detergent/dispersant content, anti-wear additive levels, and total acid number (TAN)
“The Red Line completely dominated the competition with the first place finish in every category.”
Data notes and caveats
Only 2 of the video's many sub-tests have dedicated meta chapters (Protection against Foaming, Most Robust Additive Package); everything else falls inside one large untitled chapter, so chapterMap is false despite the transcript itself being very clean and internally consistent. The evaporation and lubricity/wear-scar tests were each run as two separate pairs (ACDelco vs SuperTech, then Mobil vs Red Line) rather than as one simultaneous four-way test, though the video does synthesize a combined four-way ranking afterward for both. SuperTech's runner-up finish (average rank 2.8) comes despite it finishing dead last specifically on wear resistance, which the narrator explicitly flags as his biggest concern with that brand; this is not a contradiction, just an average across categories where SuperTech excelled at both flow-speed races. No explicit budget/value pick is framed by the narrator in this video (unlike some other Project Farm videos), so budgetPick is left null even though ACDelco is the cheapest brand tested at about $8 per quart; it did not perform particularly well overall (last or near-last in cooked flow speed and both cold-flow races).
