Every dealership pitches its own brand of full synthetic oil like it is the one your engine actually needs, and every auto parts counter has a house brand claiming the same protection for less. The bottles all say API SP or Dexos 1 or ILSAC GF-6, the labels all promise better wear protection and cleaner engines, and almost none of that tells you which one is genuinely better under a microscope.
So a hands-on tester bought six full synthetic oils, five of them OEM brands (Motorcraft, Mopar, ACDelco, Honda, and Toyota) plus Mobil 1 as the aftermarket benchmark, and ran them through the same lab and bench gauntlet. The results were not what you would guess from the price tags.
Here is what actually came out on top.
What the testing showed
Every number below comes from Project Farm's independent bench and lab testing. You can watch the full comparison on the complete OEM motor oil test, which pits Honda, Toyota, and ACDelco's factory-fill oils directly against Motorcraft, Mopar, and the aftermarket Mobil 1.
All six oils went through the same gauntlet: a cold oil flow race at room temperature, a Noack-style evaporative loss test (200 grams of oil heated to about 410F for two hours), a lubricity and wear-scar test under a microscope, a repeat cold flow race using the heat-exposed oil, a repeat cold flow race at negative 40F, and an independent oil lab analysis covering wear metals, detergent and dispersant additives, anti-wear package, and total base number.
Motorcraft came out on top, combining bench results with lab data
Motorcraft's full synthetic, at around 20 dollars a quart, finished first when the race results were combined with the independent lab analysis. The tester's own summary: "Combining my test results with the oil testing labs results, the Motorcraft oil came out on top with an average finish of 2.2." Mopar's MaxPro Full Synthetic and ACDelco's Full Synthetic were close behind at 3.0 and 3.2 respectively, a tight cluster at the top.
ACDelco won the wear-resistance test outright, but that was not the whole story
ACDelco, priced at 18 dollars a quart, won the lubricity (wear-scar) test outright across all six oils, meaning it did the best job of preventing metal-on-metal wear under the microscope. But the overall ranking weighs more than a single category, and ACDelco settled into third place once cold flow performance and lab chemistry were factored in alongside the wear result.
Toyota's factory oil surprised the tester, and not in a good way
Toyota's oil won the cold-flow-at-negative-40F race outright, the toughest cold-weather test in the video. But it also posted the weakest independent lab results of all six oils, including the lowest anti-wear additive package and the lowest total base number (the measure of an oil's ability to neutralize acid over its service life). The tester's reaction: "I'm pretty surprised that the Toyota didn't do a lot better," since strong cold flow did not translate into strong wear protection or long-term chemistry.
Mobil 1 dominated the races but still finished outside the top four
Mobil 1's Advanced Fuel Economy oil, the least expensive of the six at 12 dollars, won or tied for first in every single cold-flow race format in the video. On raw flow speed it was arguably the best performer of the group. Yet it landed outside the top four in the combined overall ranking, which the tester flagged directly: "I'm pretty surprised that the top four brands outperformed Mobile 1." Fast flow and strong wear protection are not the same thing, and this test is the clearest illustration of that gap in the whole lineup.
How to read this for your own purchase
The headline lesson here is that no single number tells the whole story. An oil that wins the cold-flow race can still finish near the bottom overall if its wear protection and additive package are weak, and an oil that wins the wear test can lose ground on cold-weather performance. The combined ranking, not any one test, is what should guide a purchase.
If you drive an OEM vehicle covered by Motorcraft, Mopar, or ACDelco's factory-fill spec, the testing supports sticking with the manufacturer oil rather than switching to save a few dollars. All three finished in a tight cluster at the top of the combined ranking.
If you drive a Honda or Toyota and are considering a swap to a cheaper aftermarket oil, know that Toyota's own factory oil had real weaknesses in the lab analysis despite winning the cold-weather race, so a well-reviewed aftermarket full synthetic that meets your API spec is a reasonable alternative to consider, not a downgrade by default.
A few rules the testing backs up regardless of brand:
- Match the API and ILSAC certification to your owner's manual first. Every oil in this test carried the right certification for its intended vehicle; buying outside spec undermines any lab advantage a given oil has.
- Do not assume a fast-flowing oil is automatically the best protector. Mobil 1's Advanced Fuel Economy oil proved the opposite can be true: excellent flow, middling overall wear protection.
- Total base number matters for oil-change intervals. A lower TBN, like Toyota's in this test, means the oil loses its acid-neutralizing capacity faster, which is a real consideration if you tend to stretch oil changes past the recommended interval.
Curious how these full synthetics compare to diesel-rated and other oil types? Browse the rest of the engine oil and fluids tests for more brand-versus-brand breakdowns pulled from the same kind of bench and lab testing.