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, the three most important ratings of the ones that we compared above are viscosity index, pour point, and Cold Cranking Viscosity (CCS). 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.

Mobil 1 V-Twin vs AMSOIL

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.

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.

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.

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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.

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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.

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 and less viscosity breakdown over Mobil 1 in independent lab testing.

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.