Valvoline has been an American institution since 1866 and is one of the most recognized motor oil brands at every Walmart, AutoZone, and quick-lube shop. AMSOIL Signature Series is the flagship of the company that brought the first API-rated synthetic motor oil to market in 1972. Both make full synthetics — but they're built for different drivers. Here's an honest, data-driven comparison.
Quick Verdict
AMSOIL Signature Series outperforms Valvoline Advanced Full Synthetic in independent ASTM testing across wear protection, NOACK volatility, and TBN reserve — and it's rated for 25,000-mile drain intervals versus Valvoline's standard OEM interval. Valvoline is a solid, widely available synthetic and a good choice if you're committed to 5,000-mile changes. AMSOIL is the better choice for maximum protection, extended drain intervals, and lower cost per mile.
Drain Interval Differences
This is where the two oils differ most. Valvoline Advanced Full Synthetic is rated to follow your OEM service interval (typically 7,500–10,000 miles). Valvoline Extended Protection is rated for up to 20,000 miles. AMSOIL Signature Series is rated for 25,000 miles or 1 year, whichever comes first, in normal service. Over 100,000 miles, that's roughly 4 AMSOIL changes versus 10–13 Valvoline changes.
Wear Test Results
The ASTM D6891 Sequence IVA test measures camshaft lobe wear under sustained load — the closest standardized proxy for real-world engine wear. AMSOIL Signature Series 5W-30 averaged ~2.9 microns of wear in published third-party testing. Valvoline Advanced Full Synthetic typically lands in the 7–10 micron range. For a normal commuter, both protect well; for a vehicle you intend to keep past 200,000 miles, the gap matters.
High-Mileage Engine Options
Valvoline MaxLife is the brand's high-mileage product, formulated with seal conditioners and slightly higher viscosity to address oil consumption and seal weeping common in 75,000+ mile engines. It's a respected formulation.
AMSOIL's answer for high-mileage engines is Signature Series itself — its low-NOACK, ester-fortified base oil keeps seals supple and reduces oil consumption naturally — plus AMSOIL Z-ROD for older or stored vehicles, and AMSOIL Premium Protection 10W-30 / 20W-50 for higher-mileage engines that prefer thicker grades. In real-world reports, switching from MaxLife to Signature Series often reduces oil consumption further because of AMSOIL's lower NOACK volatility.
TBN Retention
TBN (Total Base Number) measures the oil's reserve capacity to neutralize combustion acids. Higher starting TBN and slower TBN depletion = the oil can safely protect for longer. AMSOIL Signature Series starts around TBN 12–13. Valvoline Advanced Full Synthetic typically starts around TBN 8–9. In used-oil analysis, AMSOIL Signature Series routinely retains usable TBN past 15,000 miles, which is what makes the 25,000-mile drain interval defensible.
Head-to-Head: The Spec Sheet
- Drain interval: AMSOIL Signature Series 25,000 mi / 1 yr • Valvoline Advanced 7,500–10,000 mi (OEM)
- NOACK volatility: AMSOIL ~6% • Valvoline Advanced ~10–12%
- Starting TBN: AMSOIL ~12–13 • Valvoline Advanced ~8–9
- Sequence IVA wear: AMSOIL ~2.9 microns • Valvoline Advanced ~7–10 microns
- Pour point (5W-30): AMSOIL ~ -49°F • Valvoline ~ -40°F
- Warranty: Both warranty-compatible (Magnuson-Moss Act)
Value Per Mile
Sticker price per quart isn't the right metric — cost per mile of protection is. Here's a realistic comparison over 25,000 miles assuming a 6-quart sump:
- Valvoline Advanced @ 7,500-mile intervals: ~3.3 oil changes • ~20 quarts • 3 filters • 3 service events
- AMSOIL Signature Series @ 25,000-mile interval: 1 oil change • 6 quarts • 1 premium filter • 1 service event
With Preferred Customer pricing (25% off retail), AMSOIL Signature Series typically beats Valvoline on cost per mile, and the gap widens once you factor in fewer filters, less labor, and less waste oil disposal. For fleets and high-mileage drivers, the savings are real and measurable.
Where AMSOIL Wins
- Lower wear in Sequence IVA testing
- Lower NOACK volatility / less oil consumption
- Higher TBN reserve / safer extended drain intervals
- Better cold-flow performance
- Lower cost per mile with Preferred Customer pricing
Where Valvoline Wins
- Available everywhere — every Walmart, AutoZone, and quick-lube shop
- Lower sticker price per quart at retail
- Strong, well-known high-mileage product (MaxLife)
- Easy choice for drivers committed to 5,000-mile changes
Frequently Asked Questions
Is AMSOIL better than Valvoline?
In published third-party ASTM testing, AMSOIL Signature Series outperforms Valvoline Advanced Full Synthetic in wear protection (Sequence IVA), NOACK volatility, and TBN reserve. Valvoline is a quality full-synthetic available everywhere, but AMSOIL is engineered for longer drain intervals and uses a more robust additive package.
What is the drain interval for Valvoline vs AMSOIL Signature Series?
Valvoline Advanced Full Synthetic is rated to follow your OEM service interval, typically 7,500–10,000 miles. AMSOIL Signature Series is rated for up to 25,000 miles or 1 year, whichever comes first, in normal service.
Should high-mileage engines use Valvoline MaxLife or AMSOIL?
Valvoline MaxLife is a popular high-mileage option with seal conditioners. AMSOIL also makes an excellent high-mileage choice — Signature Series has a robust additive package that keeps seals supple, and AMSOIL Z-ROD or Signature Series with extended drain capability often outperforms MaxLife on wear and oil consumption in older engines.
Is Valvoline cheaper than AMSOIL?
Per quart at retail, Valvoline is usually less expensive than AMSOIL Signature Series. However, with Preferred Customer pricing (25% off) and a 25,000-mile drain interval, AMSOIL's cost per mile of protection is typically lower than Valvoline changed every 7,500–10,000 miles.
Can I switch from Valvoline to AMSOIL without flushing?
Yes. AMSOIL synthetic motor oil is fully compatible with Valvoline and other synthetic oils. No flush required — drain the Valvoline, replace the filter, and refill with AMSOIL.
Ready to Try AMSOIL?
Shop AMSOIL Signature Series direct, register as a Preferred Customer to save 25% on every order, or contact Eric Riley for personalized product recommendations.