Start with fitment.
Look up your exact year, make, model, and engine in AMSOIL’s vehicle guide. Match the viscosity and required specifications in your owner’s manual. The same viscosity on two bottles does not make them interchangeable. This comparison covers gasoline-engine oil; diesel and European applications may need different products.
Compare the three oil families.
All three are 100% synthetic. Their service recommendations differ. The limits below come from AMSOIL’s linked data bulletins, reviewed October 3, 2026, and apply to eligible U.S. and Canadian applications.
On a small screen, scroll the table sideways to see both service limits.
| Oil family | Why consider it? | Normal service limit | Severe service limit |
|---|---|---|---|
| OE | Synthetic protection while keeping the vehicle maker’s maintenance schedule. | Follow the vehicle manufacturer’s interval or oil-life monitor. Replace the filter with each oil change. | |
| Extended-Life | A boosted additive package for cleanliness and longer eligible oil-change intervals. | Up to 20,000 miles or one year, whichever occurs first. | Up to 12,000 miles or one year, whichever occurs first. |
| Signature Series | AMSOIL’s premium gasoline oil family, with its longest eligible interval of these three choices. | Up to 25,000 miles, 700 operating hours, or one year—stop at the first limit reached. | Up to 15,000 miles, 700 operating hours, or one year—stop at the first limit reached. |
These are conditional maximums, not a service prescription for every engine. Frequent towing, hauling, plowing, dusty driving, excessive idling, and commercial or fleet use fall under AMSOIL’s severe-service guidance.
For Extended-Life and Signature Series, modified engines, racing, and alternative fuels such as E85 are excluded from extended-drain recommendations. Mixed oils do not qualify for those extended intervals. Follow the filter’s service limits; with other-brand filters, AMSOIL caps filter use at 12,000 miles or one year unless the vehicle manufacturer specifies longer. Check oil levels regularly and change the filter when changing oil.
Read the full application and service conditions: OE data bulletin (PDF), Extended-Life data bulletin (PDF), and Signature Series data bulletin (PDF).
Make the choice in three steps.
- Confirm compatibility. Record your required viscosity and manufacturer specification before shopping.
- Describe your driving. Include annual mileage, short trips, towing, idling, and any engine modifications when asking for help.
- Set an oil and filter plan. Choose OE for the manufacturer’s schedule, or compare the full Extended-Life and Signature Series conditions if you want to evaluate longer service.
Browse gasoline motor oils → · Plan for cold weather and storage →
Plan for your stage of ownership.
High-mileage maintenance and printable oil log · Hybrid oil questions and service planner · Seasonal equipment checklists
LOCAL HELP / LEWISTON–CLARKSTON
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