"Is AMSOIL really better than Mobil 1?" It's the question I get asked more than any other. Both are full-synthetic motor oils, both have loyal followings, and both will outperform conventional oil. But when you dig into independent test data, additive chemistry, and drain interval claims, real differences emerge. Here's an honest, data-driven comparison.
Quick Verdict
AMSOIL Signature Series outperforms Mobil 1 Extended Performance in independent ASTM testing across wear protection, volatility, and deposit resistance — by significant margins. Mobil 1 is a good oil and widely available. AMSOIL is engineered for enthusiasts, fleets, and anyone who wants the absolute best protection and the longest drain interval.
Head-to-Head: The Spec Sheet
- Drain interval: AMSOIL Signature Series 25,000 mi / 1 yr • Mobil 1 EP 20,000 mi / 1 yr
- NOACK volatility (lower = less oil burn): AMSOIL ~6% • Mobil 1 EP ~9-10%
- TBN (acid neutralization): AMSOIL ~12-13 • Mobil 1 EP ~9-10
- Sequence IVA wear: AMSOIL up to 75% better than Mobil 1 in published 3rd-party test
- Pour point (cold flow): AMSOIL -49°F • Mobil 1 EP -42°F (5W-30)
- Warranty: Both warranty-compatible (Magnuson-Moss Act)
Wear Protection
In the industry-standard ASTM D6891 Sequence IVA test (which measures camshaft wear under high-stress conditions), AMSOIL Signature Series 5W-30 averaged just 2.9 microns of wear compared to Mobil 1 Extended Performance at 11.8 microns and Mobil 1 Annual Protection at 13.4 microns. That's a meaningful difference if you keep your vehicles long-term.
Volatility & Oil Consumption
NOACK volatility measures how much oil evaporates at high temperatures. Lower NOACK = less oil consumption and fewer deposits. AMSOIL Signature Series posts NOACK numbers around 6%, well below the API limit of 15% and significantly below Mobil 1 EP's ~9-10%. If your engine burns oil between changes, switching from Mobil 1 to AMSOIL often reduces consumption noticeably.
Drain Intervals & Cost-Per-Mile
AMSOIL Signature Series is rated for 25,000 miles / 1 year. Mobil 1 Extended Performance is 20,000 miles / 1 year. With Preferred Customer pricing, AMSOIL Signature Series costs less per mile of protection than Mobil 1 EP at retail — and far less when you factor in fewer oil changes and less downtime.
Where to Buy
Mobil 1 is available at Walmart, AutoZone, and most parts stores. AMSOIL is sold direct through Independent Dealers like me — which means no retail markup, factory-fresh inventory, and personal product support. As a Florida-based dealer, I can ship to your door anywhere in the U.S. or set you up with a wholesale Preferred Customer account.
Frequently Asked Questions
Is AMSOIL better than Mobil 1?
Independent third-party testing (ASTM Sequence IVA wear, Noack volatility, TEOST 33C deposit) consistently shows AMSOIL Signature Series outperforms Mobil 1 Extended Performance and Mobil 1 Annual Protection in wear protection, volatility, and high-temperature deposit resistance. Both are fully synthetic, but AMSOIL uses a more robust additive package and longer-chain Group IV/V base stocks.
What is the difference between AMSOIL Signature Series and Mobil 1 Extended Performance?
AMSOIL Signature Series is engineered for 25,000-mile / 1-year drain intervals. Mobil 1 Extended Performance is rated for 20,000 miles / 1 year. AMSOIL also offers higher TBN (Total Base Number) for longer acid-neutralization capacity and lower NOACK volatility (less oil burn-off).
Does AMSOIL or Mobil 1 protect better against engine wear?
AMSOIL Signature Series demonstrated up to 75% better engine protection against wear than Mobil 1 Extended Performance and Mobil 1 Annual Protection in third-party Sequence IVA testing. AMSOIL publishes the full third-party reports.
Is AMSOIL more expensive than Mobil 1?
Per quart, AMSOIL Signature Series typically costs more than Mobil 1 Extended Performance at retail. However, with Preferred Customer pricing (25% off) and longer drain intervals (25,000 vs 20,000 miles), the cost-per-mile of AMSOIL is competitive or lower than Mobil 1 over time.
Can I switch from Mobil 1 to AMSOIL without flushing?
Yes. AMSOIL synthetic motor oil is fully compatible with Mobil 1 and other synthetic oils. No flush required — simply drain your Mobil 1, change the filter, and refill with AMSOIL.
Try AMSOIL Signature Series
Shop the full Signature Series lineup, or register as a Preferred Customer to save 25% on every order.