2019 test2 productsEngine Oil & Fluids
Which Synthetic Motor Oil Brand Wins?
We compared 2 synthetic motor oil options head to head. Amsoil came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Winner
Amsoil
Price shown in test: $12.85 per quart
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Runner-up
Royal Purple
Price shown in test: $9.78 per quart
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The measured results
Every number below is read straight from the test. Scroll sideways to see all measurements. Products are listed in the order they finished.
| Product | Lubricity wear scar | Evaporative loss (200g oil, 375-400F for 2hr) | Cold oil flow at -15F, 24hr freezer soak (4-lane race, new and heat-exposed 'cooked' samples) |
|---|---|---|---|
| 1Amsoil Signature Series$12.85 per quart | approximately 13% smaller than Royal Purple's, described as the winner of this test; no absolute measurement given, only the relative percentage | before-heating weight 414.76 g; the after-heating weight is never spoken in the transcript (likely shown on screen only), so the actual weight lost cannot be confirmed from narration alone | new Amsoil finished 1st of all 4 lanes, beating cooked Amsoil by less than 1 inch, new Royal Purple by over 3 inches, and cooked Royal Purple by nearly 5 inches; cooked Amsoil finished 2nd, still ahead of new Royal Purple by about 3 inches |
| 2Royal Purple$9.78 per quart | approximately 13% larger than Amsoil's; both oils performed impressively overall | 406.3 g before heating, 404.17 g after, a loss of about 2.13 g | new Royal Purple finished 3rd of 4 lanes (behind new Amsoil by over 3in and cooked Amsoil by about 3in, but ahead of cooked Royal Purple by less than 2in); cooked Royal Purple finished last (4th), beaten by new Amsoil by nearly 5 inches |
How it was tested
- lubricity/film strength wear scar test on a bearing tester
- informal evaporative loss test, approximately 200g oil heated to 375-400F for 2 hours (not true ASTM Noack conditions, which call for 482F for 1 hour)
- cold oil flow test at -15F after a 24hr freezer soak, new vs heat-exposed ('cooked') oil samples raced in 4 lanes
“I think Amsoil demonstrated today that it's a really, really good synthetic oil.”