AMSOIL vs Mobil 1: Which Synthetic Motor Oil Reigns Supreme?

Comparing popular synthetic motor oil brands like AMSOIL vs Mobil 1? That's a smart decision. Let's dive into these motor oil giants and take an objective approach to finding which motor oil brand rises to the top: AMSOIL or Mobil 1?

Brief History of AMSOIL & Mobil 1 Synthetics

Before getting into the stats and numbers of both brands' oil products, let's briefly touch on the history of these synthetic oil giants. When it comes to being the first, AMSOIL has Mobil 1 beat.

Al Amatuzio, the founder of AMSOIL, started researching and developing synthetic oils in the 1960's. Amatuzio formulated his first synthetic oil in 1966. He then started commercially selling synthetic oils in 1968, incorporated in 1969, and in 1970 he adopted the name "AMZOIL" which was later changed to "ASMOIL" following a lawsuit with Pennzoil. In 1972, AMSOIL's synthetic motor oil became the world's first synthetic oil to meet API service requirements, hence the adoption of the "The First in Synthetics®" tagline.

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Mobil 1 didn't begin researching synthetic motor oil internally until 1971, when they created the "New Concept Engine Oil Team." In 1973, Mobil 1 synthetic engine oil was released in Europe. And then in 1974, Mobil 1 commercially introduced their synthetic motor oil to the US.

Many speculate that big oil companies were heavily resistant to synthetic oils because they believed products like AMSOIL's - guaranteed for 25,000 miles/one year - would be detrimental to continuous sales of conventional oils, normally only spec'd for 3,000 miles between oil changes. Nowadays, all the big oil companies have followed suit and adopted several lines of full synthetic motor oils.

When it comes to who was first, AMSOIL or Mobil 1? AMSOIL beat Mobil 1 to the punch.

Regardless, being the first doesn't mean a product is any better, so let's look at product specifications and testing of AMSOIL vs. Mobil 1.

Comparing AMSOIL & Mobil 1 Synthetic Motor Oils

Top AMSOIL Gas Motor Oil

From the AMSOIL oil comparison chart, it's clear their best oil line for gas engines is the Signature Series. AMSOIL's Signature Series oils can be found in 0W-20, 0W-30, 0W-40, 5W-20, 5W-30, 5W-50, and 10W-30 weights.

Best Mobil 1 Gas Motor Oil

Mobil 1 Extended Performance touts 20,000 of protection guaranteed, so we'll use that for comparing gas engine oils. It's available in 0W-20, 5W-20, 5W-30, and 10W-30 weights which will be directly cross-referenced to the same weights of AMSOIL Signature Series.

AMSOIL Signature Series vs. Mobil 1 Extended Performance

While both manufacturers do list some oil ratings & specifications for the selected oils, they don't match up perfectly, so we'll compare them as closely as possible. First up, we're comparing AMSOIL Signature Series 5W-30 (ASLQT-EA) with Mobil 1 Extended Performance 5W-30.

Manufacturer Specified Ratings

*hover over each specification for more details.

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Of the 9 oil ratings/specifications that were compared above, AMSOIL has topped Mobil 1 in 6 of them, taking an early lead. But not all of those ratings equally factor into the quality of any given motor oil. In my experience as an Automotive Engineer at Ford and lifelong gearhead, the three most important ratings of the ones that we compared above are viscosity index, pour point, and Cold Cranking Viscosity (CCS). These metrics give us a better idea on how the oil will perform throughout the course of it's lifespan and especially how it performs in colder weather and at engine startup. AMSOIL still has the lead out of only those specs.

Other important factors to compare are the oil additives by PPM (Parts Per Million). Many types of additives are added to motor oils for various reasons. Some act as detergents, dispersants, anti-wear agents, rust & corrosion inhibitors, and anti-foaming agents to name a few. Neither manufacturer provides exhaustive lists of the total additives added to their oils. But we will provide comparison performance tests which give us a general idea.

AMSOIL Signature Series vs. Mobil 1 EP - Pricing Breakdown

Out of the gate, AMSOIL Signature Series is a lto more expensive than Mobil 1 Extended Performance.

Normal Service Cost Comparison:

Under normal driving conditions (15,000 miles per year), AMSOIL Signature Series costs approximately 60-70% more per quart than Mobil 1 Extended Performance. However, over a 5-year period with 75,000 miles of driving, you'd need just 3 oil changes with AMSOIL, if you go over the 1 year oil change recommandation (thanks to its 25,000-mile drain interval) compared to 4 oil changes with Mobil 1 (with its 20,000-mile interval). This results in AMSOIL being roughly 20-25% more expensive over five years. For drivers covering more than 20,000 miles annually, the math shifts dramatically in AMSOIL's favor, potentially making it less expensive over time despite the higher initial cost.

Severe Service Cost Comparison:

The value proposition becomes even more compelling under severe service conditions. AMSOIL Signature Series maintains a 15,000-mile drain interval for severe service, while Mobil 1 Extended Performance reverts to standard OEM recommendations (typically 5,000-7,500 miles). Over five years of severe service driving (75,000 miles), you would need 5 oil changes with AMSOIL compared to 10-15 changes with Mobil 1. Even with AMSOIL costing 60-70% more per quart, the total 5-year cost for Mobil 1 would be approximately 100-200% higher than AMSOIL when factoring in oil, filters, and labor. For commercial applications or vehicles regularly used for towing, this difference can translate to significant maintenance savings and reduced vehicle downtime.

AMSOIL OE vs. Mobil 1: Everyday Performance Comparison

While AMSOIL Signature Series and Mobil 1 Extended Performance represent the premium oils from both manufacturers, you might be looking for quality synthetic oils at a more accessible price point. AMSOIL OE 5W-30 and Mobil 1 5W-30 Full Synthetic are designed to meet this need, providing excellent protection for vehicles maintained according to manufacturer-recommended drain intervals.

Specifications and Approvals

AMSOIL OE 5W-30:

• API SP (Resource Conserving), SN PLUS, SM
• GM dexos1 Gen 2
• ACEA A1/B1, A5/B5
• Chrysler MS-6395
• Ford WSS-M2C946-A, WSS-M2C929-A
• ILSAC GF-6A, GF-5, GF-4
• Honda HTO-06

Mobil 1 5W-30 Full Synthetic:

• API SP, SN PLUS
• ILSAC GF-6A
• GM dexos1 Gen 2
• Meets requirements for Ford and Chrysler vehicles

Both oils meet or exceed the latest industry specifications, with AMSOIL OE having a slightly longer list of manufacturer approvals. The most important certifications (API SP, ILSAC GF-6A, and GM dexos1 Gen 2) are shared by both products.

Technical Comparison - AMSOIL OE vs. Mobil 1

*hover over each specification for more details.

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From the technical specifications, several important observations can be made:

1. Superior High-Temperature Protection: AMSOIL OE has slightly higher viscosity measurements at both 40°C and 100°C, suggesting better protection at operating temperatures. The higher High-Temperature/High-Shear (HTHS) viscosity of 3.3 versus "not specified" for Mobil 1, indicates better protection for bearings and high-stress components.
2. Better Viscosity Stability: AMSOIL OE's documented Viscosity Index of 168 shows excellent resistance to thinning at high temperatures. Mobil 1 doesn't specify this critical parameter in its documentation.
3. Cold Weather Performance: AMSOIL has a slightly better pour point (-42°C vs -44°C), but the difference is negligible for most climates. Without Mobil 1's Cold Crank Viscosity data, it's difficult to make a complete cold-weather performance comparison.
4. Long-Term Engine Protection: AMSOIL's specified TBN of 8.0 indicates good acid-neutralizing capabilities, while Mobil 1 doesn't disclose this important longevity metric. AMSOIL also provides NOACK Volatility data (9.4%), while Mobil 1 doesn't, suggesting more transparency about oil consumption characteristics.
5. Flash Point Advantage to Mobil 1: The significantly higher flash point of Mobil 1 (242°C vs 220°C) may provide better resistance to breakdown in extremely high-temperature conditions.
6. Comparable OEM Approvals: Both oils meet the latest API SP and ILSAC GF-6A standards and have similar OEM approvals, though Mobil 1 lists more API backward compatibility.

Pricing - AMSOIL OE vs. Mobil 1

The two product we've compared above are some of the cheapest full synthetic options from both brands, and they are fairly similarly priced. At retail prices, AMSOIL OE is a couple bucks more expensive per quart, but with their Preferred Customer discount, AMSOIL OE is actually a little bit cheaper than Mobil 1 Full Synthetic.

It's also important to note that AMSOIL does not recommend extending drain intervals with their OE line of oils, while Mobil 1 Full Synthetic is rated for 10,000 miles.

Mobil 1 V-Twin vs AMSOIL V-Twin Oil

Mobil 1 and AMSOIL also produce dedicated V-Twin motorcycle oils that are recommended for Harley Davidson's. How do these oils stack up with the manufacturer-listed specifications? *Note: both manufacturers don't use the exact same specs for their data, so we'll only compare specifications that both manufacturers provide.

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Of the matched specifications, AMSOIL again comes out on top with their V-Twin 20W-50 Oil having better ratings for Viscosity Index and Pour Point.

Let's also compare the specification approvals for AMSOIL V-Twin 20W-50 and Mobil 1 V-Twin 20W-50:

AMSOIL V-Twin 20W-50 Approvals:

• JASO MA/MA-2
• API SL, SH, SG, CG-4, CF
• ISO-L-EMA2
• Suitable for use in motorcycles that require an API CH-4 oil
• Not to be used where an API GL-4 or GL-5 gear oil is required

Mobil 1 V-Twin 20W-50 Approvals:

• Recommended for applications requiring: API CF, API SH, API SG
• Meets or exceeds the requirements of: API SJ

Key differences and discussion:

1. JASO MA/MA-2: AMSOIL's oil meets this Japanese standard specifically designed for motorcycle oils. This approval isn't listed for the Mobil 1 oil. JASO MA/MA2 certification ensures the oil is suitable for wet clutch applications, which is crucial for many motorcycles.
2. API Standards:
   • Both oils meet API SH and SG standards for gasoline engines.
   • AMSOIL meets the more recent API SL standard, while Mobil 1 meets API SJ. API SL is a more recent standard than SJ, potentially indicating better performance in areas like deposit control and oil consumption.
   • AMSOIL also meets API CG-4, which is a diesel engine oil standard. This isn't typically necessary for motorcycles but could be beneficial for some applications.
3. ISO-L-EMA2: AMSOIL meets this International Organization for Standardization spec for 4-stroke motorcycle engines. This isn't listed for Mobil 1 and provides additional assurance of the oil's suitability for motorcycles.
4. API CH-4 suitability: AMSOIL mentions suitability for applications requiring API CH-4, another diesel engine oil standard. This isn't mentioned for Mobil 1 and isn't typically necessary for motorcycles.
5. Gear Oil warning: AMSOIL specifically mentions not to use their oil where API GL-4 or GL-5 gear oils are required. This warning isn't present for Mobil 1, but it's generally assumed that engine oils shouldn't be used as gear oils unless specifically stated.

Overall, the AMSOIL V-Twin 20W-50 appears to have a broader range of approvals and meets more recent API standards. The JASO MA/MA2 and ISO-L-EMA2 approvals specifically target motorcycle applications, which could be seen as an advantage for AMSOIL in this context.

Mobil 1's approvals, while fewer, still cover the essential API standards for gasoline engines. The API SJ standard it meets is still widely accepted, even if it's not the most recent.

Mobil 1 V-Twin vs. AMSOIL V-Twin Oil Pricing Breakdown

For normal riding conditions, AMSOIL V-Twin 20W-50 costs approximately 45-50% more per quart than Mobil 1 V-Twin at retail pricing. However, with the Preferred Customer discount, AMSOIL's price premium drops to around 13% more than Mobil 1. For a typical motorcycle rider covering 5,000 miles per year, AMSOIL's extended drain interval recommendation (twice the manufacturer's interval) means you'd need half as many oil changes as with Mobil 1. This could make AMSOIL approximately 30-40% less expensive over several years for normal riding conditions.

For hardcore riders putting serious miles on their Harleys, the cost difference becomes even more significant. A rider covering 10,000 miles annually under challenging conditions would need 2 oil changes per year with AMSOIL versus 4 with Mobil 1 (assuming a severe service interval of 2,500 miles). Over five years and 50,000 miles, this means 10 oil changes with AMSOIL compared to 20 with Mobil 1. When factoring in the cost of oil, filters, and labor/time, Mobil 1 would cost approximately 75-100% more than AMSOIL over this period, even with AMSOIL's higher per-quart price. For touring riders who travel long distances, this represents significant savings in both maintenance costs and valuable riding time that would otherwise be spent on additional oil changes.

Independent Testing: AMSOIL vs. Mobil 1

The Kurt Orbahn Test

The Kurt Orbahn test (ASTM D6278) evaluates the shear stability of oils, measuring the percent viscosity loss at 100°C. Independent testing revealed that AMSOIL Signature Series blew the competition away with the lowest percent viscosity lost in this test. AMSOIL fights viscosity breakdown 46% better than Mobil 1 (based on independent testing of AMSOIL Signature Series 5W-30, Schaeffer's Supreme 9000 Full Synthetic, Lucas Synthetic, Valvoline Conventional Daily Protection, Mobil 1 Annual Protection and Pennzoil 5W-30).

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Oil Volatility Testing (ASTM D5800)

Another test showed AMSOIL fights volatility 38% better than Mobil 1 and 17% better than Royal Purple, which helps reduce oil consumption and keep valves clean during engine operation. Based on independent testing of AMSOIL SS 5W-20, Mobil 1 Advanced Synthetic 5W-20, Royal Purple HP 5W-20, Valvoline Advanced, Pennzoil Platinum, Valvoline High Mileage, Mobil 1 Annual Protection, Schaeffer's Supreme 9000, Lucas Oil, Pennzoil conventional and Valvoline Daily Protection.

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ASTM D2896 Testing

The ASTM D2896 test determines the Total Base Number (TBN) of oils and confirms the additives included in any blend of oil. Based on independent testing of AMSOIL Signature Series 5W-30 and Mobil 1 Annual Protection Full Synthetic 5W-30, AMSOIL delivers 28% more acid-neutralizing power than Mobil 1.

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ASTM D6335 Testing (TE0ST)

A third-party lab performed the ASTM D6335 Thermo-oxidation Engine Oil Simulation Test (TE0ST) 33C which simulates deposit foundation found in a turbocharger and is required for the API SN Resource Conserving specification. AMSOIL Signature Series performed 4X better than Mobil 1 Extended Performance and 3.6X better than Royal Purple.

For a detailed comparison of AMSOIL ATV/UTV motor oil with Mobil 1 and Polaris oil, visit this article.

Another independent ASTM D6335 test showed that AMSOIL 0W-20 High-Mileage Motor Oil provides up to 62% better deposit prevention than Mobil 1 and Valvoline (based on independent testing of AMSOIL 0W-20 100% Synthetic High-Mileage Motor Oil, Valvoline Full Synthetic High-Mileage with MaxLife Technology 0W-20 Motor Oil (batch codeJ2622C5 purchased December 21, 2022) and Mobil 1 High-Mileage 0W-20 Full Synthetic Motor Oil (batch code 11022L21A 6606 purchased December 8, 2022) in the industry-standard TEOST 33C Test (ASTM D6335) as required by the ILSAC GF-6 specification).

ASTM D5293 Testing

AMSOIL 100% Synthetic Hybrid Motor Oil provides up to 16% better low-temperature viscosity than Mobil 1, delivering better protection at startup. Based on independent, third-party testing of AMSOIL 0W-20 100% Synthetic Hybrid Motor Oil and Mobil 1 0W-20 Hybrid Full Synthetic Motor Oil (batch code 10222M14A RN6613 326900 D340BUDE015 purchased April 17, 2023) in the industry-standard ASTM D5293 Cold Crank Simulator test as required by SAE J300.

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AMSOIL or Mobil 1 Synthetic?

When comparing prices, AMSOIL is typically more expensive than Mobil 1. If you're strictly shopping by upfront cost, Mobil 1 is the better choice. However, with AMSOIL's 25,000 mile service life and superior performance testing results, you'll save money in the long run by going with AMSOIL.

If you want to enjoy better engine performance, longer drain intervals, lower maintenance costs and better peace of mind, AMSOIL is the obvious choice.

Consider AMSOIL's Preferred Customer Program, where for a simple $20 per year you can save up to 25% on all AMSOIL products, get free shipping on orders of $100 or more, and enjoy other perks and benefits.

Is AMSOIL better than Mobil 1?

AMSOIL is a higher quality oil than Mobil 1, delivering more acid-neutralizing power, lower volatility, less viscosity breakdown, and better deposit prevention over Mobil 1 in independent lab testing.

Is AMSOIL worth the higher price?

While AMSOIL products typically cost 40-70% more per quart than comparable Mobil 1 oils, they provide significantly better value when considering the extended drain intervals they offer. For normal driving conditions, AMSOIL Signature Series allows 25,000-mile/1-year drain intervals compared to Mobil 1's 20,000 miles, and in severe service conditions, the difference is even more dramatic—15,000 miles for AMSOIL versus standard 5,000-7,500 mile intervals for Mobil 1. These extended intervals mean fewer oil changes, leading to reduced annual maintenance costs despite the higher per-quart price.

Beyond the direct cost savings, AMSOIL provides superior performance benefits supported by independent testing, including better deposit prevention (62% better than Mobil 1 in TEOST testing), improved acid-neutralizing capability (28% higher TBN), and better resistance to viscosity breakdown (46% better in the Kurt Orbahn test). Factor in less vehicle downtime, fewer disposal concerns, and the potential for extended engine life due to superior protection, and AMSOIL's higher initial cost represents a worthwhile investment for those wanting optimal engine protection and lower total ownership costs over time.

Is it safe to mix AMSOIL and Mobil 1?

While it is safe to mix different brands of oil like AMSOIL and Mobil 1 (and mix synthetic with conventional) it is NOT recommended, since you will degrade the performance of both oils.

References

• Mobil 1 EP Data Sheet
• Mobil 1 V-Twin 20W-50 Data Sheet
• Mobil 1 Full Synthetic 5W-30 Data Sheet
• AMSOIL SS 5W-30 Data Sheet
• AMSOIL V-Twin 20W-50 Data Sheet
• AMSOIL OE 5W-30 Data Sheet

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