Pennzoil Platinum is the full synthetic Pennzoil makes from natural gas. AMSOIL Signature Series is the top motor oil from the company whose 10W-40 became the first synthetic motor oil to meet American Petroleum Institute service requirements, in 1972 (AMSOIL). This post lines up the two 5W-30s using each company's own data sheet. If a number isn't published, I leave it blank.
Quick Take
The biggest published difference is the drain interval. AMSOIL rates Signature Series for up to 25,000 miles or one year in normal service (AMSOIL data sheet, AMSOIL oil change interval). Pennzoil's current sheet lists up to 15,000 miles or one year, and only under its enrollment conditions (Pennzoil TDS). AMSOIL also prints NOACK and TBN, and Pennzoil's sheet doesn't. Both list API SQ and ILSAC GF-7A. I have also compared AMSOIL with Castrol Edge, Valvoline, and Mobil 1, and you can look up oil for your car or light truck.
Made From Natural Gas
Pennzoil's data sheet calls Platinum the first motor oil made with natural gas. It also says Platinum helps keep pistons cleaner than required by the toughest industry standard, based on the ILSAC GF-7A Sequence IIIH test (Pennzoil TDS). AMSOIL's data sheet describes Signature Series as built on advanced synthetic base oils and doesn't name the base oil type, so I won't guess at it.
Side by Side: 5W-30
| Item | AMSOIL Signature Series 5W-30 (ASL) | Pennzoil Platinum 5W-30 (Aug 2026 TDS) |
|---|---|---|
| Drain interval | Up to 25,000 mi, 700 hr or 1 yr (normal); up to 15,000 mi (severe) [1] [3] | Up to 15,000 mi or 1 yr, only with Pennzoil's enrollment conditions (see below) [2] |
| API / ILSAC | API SQ (Resource Conserving), SP; ILSAC GF-7A, GF-6A [1] | API SQ, SQ Resource Conserving; ILSAC GF-7A [2] |
| GM | dexos1 Gen 3 [1] | dexos not listed on the TDS [2] |
| Ford | WSS-M2C946-A/B1, WSS-M2C961-A1, WSS-M2C971-A1 [1] | WSS-M2C971-A1 [2] |
| Chrysler | MS-6395, MS-13340 [1] | MS-6395, MS-13340 [2] |
| Viscosity @ 100°C | 10.5 cSt [1] | 10.2 cSt [2] |
| Viscosity index | 165 [1] | 166 [2] |
| CCS cold crank @ -30°C | 3,791 cP [1] | 4,822 cP [2] |
| Pour point | -48°C (-54°F) [1] | -33°C [2] |
| NOACK volatility | 5.3% [1] | Not published on the TDS |
| TBN (ASTM D2896) | 10.4 [1] | Not published on the TDS |
All figures are typical values, not specifications. Pennzoil's sheet is the Canadian-hosted version of its current technical data sheet. Check the bottle for current approvals.
Drain Intervals
AMSOIL rates Signature Series for up to 25,000 miles, 700 hours or one year in normal service. Commercial or fleet use, heavy idling, frequent towing, hauling, plowing or dusty roads count as severe service and drop it to 15,000 miles. With another brand of filter, AMSOIL says not to go past 12,000 miles or one year (AMSOIL data sheet, AMSOIL oil change interval). Pennzoil's sheet lists up to 15,000 miles or one year, but only if you use Pennzoil Platinum exclusively, use a filter made for longer intervals, follow your owner's manual and oil life sensor, and the engine is under 125,000 miles and less than 72 months old (Pennzoil TDS). If your vehicle is under warranty, the owner's manual comes first with either oil.
Cold Start and Viscosity
On the cold crank test (CCS at -30°C), lower means the oil turns over easier when it's cold. AMSOIL lists 3,791 cP and Pennzoil lists 4,822 cP. AMSOIL's pour point is -48°C (-54°F) and Pennzoil's is -33°C. At operating temperature, AMSOIL lists 10.5 cSt at 100°C and Pennzoil lists 10.2 cSt (AMSOIL data sheet, Pennzoil TDS). Here in Florida, heat matters more than cold starts.
Switching Oils
Pennzoil says Platinum can be mixed with other synthetic and mineral oils (Pennzoil TDS). AMSOIL says Signature Series is compatible with other oils, but mixing shortens its life and AMSOIL 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, drain it all and put on a new filter.
Frequently Asked Questions
Is AMSOIL better than Pennzoil Platinum?
Both 5W-30s list API SQ and ILSAC GF-7A. AMSOIL rates Signature Series for up to 25,000 miles or one year in normal service. Pennzoil's current sheet lists up to 15,000 miles or one year under its enrollment conditions. AMSOIL publishes NOACK volatility and TBN, and Pennzoil's sheet does not.
What is Pennzoil Platinum made from?
Pennzoil's data sheet calls it the first motor oil made with natural gas.
How long can I go between oil changes with Pennzoil Platinum vs AMSOIL?
AMSOIL rates Signature Series for up to 25,000 miles, 700 hours or one year in normal service, and 15,000 miles in severe service. Pennzoil's sheet lists up to 15,000 miles or one year, but only if you use Pennzoil Platinum exclusively with a filter made for longer intervals, follow your owner's manual and oil life sensor, and the engine is under 125,000 miles and less than 72 months old. If your vehicle is under warranty, follow the owner's manual.
Can I switch from Pennzoil Platinum to AMSOIL?
Yes. Both companies say their oil is compatible with other oils. AMSOIL adds that 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
- Pennzoil Platinum SAE 5W-30 Full Synthetic Motor Oil Technical Data Sheet, v3.6, August 2026. Shell (SOPUS Products). https://www.shell-livedocs.com/data/published/en-CA/f3eb958b-989f-4722-b6c4-4574861186fc.pdf
- 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/
- The AMSOIL Story. AMSOIL INC.. https://www.amsoil.com/about/
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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