A head-to-head comparison based on published specifications from AMSOIL.com and Mobil1.com. No guesswork — only verified facts.
| Feature | AMSOIL Signature Series | Mobil 1 Extended Performance |
|---|---|---|
| Oil Change Interval | 25,000 miles / 1 year (whichever comes first) | 20,000 miles / 1 year |
| Wear Protection | 75% more than industry standard (ILSAC GF-6) | Meets ILSAC GF-6 standard |
| PC Member Discount | Up to 25% off every order | No membership discount available |
| Membership Cost | $10 for 6-month trial | N/A |
| Free Shipping | On orders $100+ (PC members) | No loyalty program |
| Founded | 1972 — First in Synthetics | 1974 |
| Cost Per Mile (est.) | Lowest — fewer changes needed | Moderate — more frequent changes |
| Dealer Support | Local authorized dealer (SyntheticsTX) | Retail only |
Source: AMSOIL.com, Mobil1.com — verified April 2026
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