"Is AMSOIL better than Mobil 1?" I get that question more than any other. Here I answer it with what each company publishes about its own oil: AMSOIL Signature Series against Mobil 1 Extended Performance, both in 5W-30. If a number isn't on the data sheet, I leave it blank.
Quick Take
The headline numbers are closer than most people expect. Mobil's current U.S. data sheet lists up to 25,000 miles or one year for Extended Performance (Mobil 1), the same top-line interval AMSOIL gives Signature Series in normal service (AMSOIL). Both list API SQ and GM dexos1 Gen 3. Where they differ is the data: AMSOIL prints typical NOACK and TBN, and Mobil's U.S. sheet doesn't. AMSOIL also publishes a separate 15,000-mile severe-service rating. I have also compared AMSOIL with Castrol Edge, Pennzoil Platinum, and Valvoline, and you can look up oil for your car or light truck.
Side by Side: 5W-30
| Item | AMSOIL Signature Series 5W-30 (ASL) | Mobil 1 Extended Performance 5W-30 |
|---|---|---|
| Drain interval | Up to 25,000 mi, 700 hr or 1 yr (normal); up to 15,000 mi (severe) [1] [3] | Up to 25,000 mi or 1 yr [2] |
| API / ILSAC | API SQ (Resource Conserving), SP; ILSAC GF-7A, GF-6A [1] | Meets or exceeds API SQ, SQ Resource Conserving, SP; ILSAC GF-7A [2] |
| GM | dexos1 Gen 3 [1] | dexos1 Gen 3 approved [2] |
| Ford | WSS-M2C946-A/B1, WSS-M2C961-A1, WSS-M2C971-A1 [1] | WSS-M2C946-A, WSS-M2C946-B1, WSS-M2C961-A1, WSS-M2C971-A1 [2] |
| Chrysler | MS-6395, MS-13340 [1] | MS-6395, MS-13340 [2] |
| Viscosity @ 100°C | 10.5 cSt [1] | 10.48 cSt [2] |
| Pour point | -48°C (-54°F) [1] | -42°C [2] |
| NOACK volatility | 5.3% typical [1] | Not published on the U.S. sheet |
| TBN (ASTM D2896) | 10.4 [1] | Not published on the U.S. sheet |
All figures are typical values, not specifications. Older Mobil data sheets listed 20,000 miles for Extended Performance. The current U.S. sheet lists 25,000. An earlier version of this post used the old number.
Drain Intervals
Both oils top out at 25,000 miles or one year. AMSOIL spells out the conditions: that rating is for personal vehicles in normal service, and fleet use, heavy idling, frequent towing or dusty roads drop it to 15,000 miles. AMSOIL also says not to go past 12,000 miles or a year on another brand of filter (AMSOIL data sheet, AMSOIL oil change interval). Mobil says that if your vehicle is under warranty, you should follow the oil life monitor or the interval in your owner's manual (Mobil 1 data sheet). That's good advice for either oil.
NOACK and TBN
NOACK (ASTM D5800) measures how much oil boils off at high heat, and the ILSAC GF-7 limit is 15%. AMSOIL lists 5.3% for Signature Series 5W-30 and a TBN of 10.4 (AMSOIL data sheet). TBN is the oil's reserve for neutralizing acids from combustion. Mobil's U.S. data sheet doesn't list either one for Extended Performance (Mobil 1 data sheet), so I can't tell you how they compare.
Switching Oils
AMSOIL says Signature Series is compatible with other conventional and synthetic oils. It also says mixing shortens the oil's life and that it won't support an extended drain on mixed oil (AMSOIL data sheet, AMSOIL FAQ). AMSOIL also says mixing voids its limited warranty. If you switch from Mobil 1, drain it all and put on a new filter.
Where to Buy
AMSOIL is sold online and through Independent AMSOIL Dealers like me. I'm in Dade City, Florida. I can ship to your door, arrange local pickup, or set you up as a Preferred Customer.
Frequently Asked Questions
Is AMSOIL better than Mobil 1?
On paper the two top lines are close. Both list a drain interval of up to 25,000 miles or one year, both list API SQ, and both carry GM dexos1 Gen 3. The published difference is how much data each company prints: AMSOIL lists typical NOACK volatility and TBN for Signature Series, and Mobil's U.S. data sheet for Extended Performance does not.
What is the drain interval for Mobil 1 Extended Performance vs AMSOIL Signature Series?
Mobil's current U.S. data sheet lists up to 25,000 miles or one year for Mobil 1 Extended Performance. AMSOIL lists up to 25,000 miles, 700 hours or one year for Signature Series in normal service, and up to 15,000 miles in severe service. Mobil says to follow the oil life monitor or owner's manual while the vehicle is under warranty.
Does Mobil 1 publish NOACK or TBN for Extended Performance?
Not on the U.S. data sheet I checked. It lists density, flash point, viscosity and pour point. AMSOIL lists a typical NOACK of 5.3% and a TBN of 10.4 for Signature Series 5W-30.
Can I switch from Mobil 1 to AMSOIL?
Yes. AMSOIL states Signature Series is compatible with other conventional and synthetic motor oils. AMSOIL also says mixing shortens the oil's life and that it won't support an extended drain on mixed oil. AMSOIL also says mixing voids its limited warranty. Drain the old oil completely and put on a new filter.
Sources
- AMSOIL Signature Series 100% Synthetic Motor Oil Data Bulletin (G2880, June 2026). AMSOIL INC.. https://amsoilcontent.com/ams/lit/databulletins/g2880.pdf
- Mobil 1 Extended Performance Product Data Sheet (United States). ExxonMobil. https://www.mobil.com/en-us/passenger-vehicle-lube/pds/na-xx-mobil-1-extended-performance
- AMSOIL Oil Change Interval. AMSOIL INC.. https://blog.amsoil.com/amsoil-oil-change-interval/
- AMSOIL Frequently Asked Questions. AMSOIL INC.. https://www.amsoil.com/t/faq/
Sources checked October 16, 2026. Oil companies update formulas and data sheets. Check the current data sheet and your owner's manual before you buy.
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