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

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

Comparing top motor oil brands like AMSOIL and Mobil 1? Find out which synthetic motor oil reigns supreme, AMSOIL vs. Mobile 1.
By
Dave Mann
April 5, 2024
5 min read
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AMSOIL vs Mobil 1: Which Synthetic Motor Oil Reigns Supreme?

Top Insights

  • AMSOIL beat Mobil 1 to the punch with the first full synthetic motor oil meeting API service requirements in 1972, vs. Mobil 1 who didn't begin selling full synthetics in the US until 1974.
  • Both brands have a wide selection of full synthetic motor oil lines.
  • On paper, AMSOIL Signature Series tops Mobil 1 Extended Performance with better ratings for Kinematic Viscosity, HTHS Viscosity, Pour Point, Total Base Number (TBN), Cold Crank Viscosity, and a longer service life guarantee of 25,000 miles.
  • Mobil 1 is typically cheaper than AMSOIL, but extended drain intervals and lower maintenance costs could save you money in the long run over Mobil 1.

Meet The Author

“Hi, I’m Dave - a former Ford Truck/Automotive Engineer and the face behind Performance Oil Technology. My trucks, heavy equipment, farm and powersports vehicles experience extreme use, and I use AMSOIL products in every single one; learn more about me here. Have a question? Contact me here. Enjoy the site!”

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.

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.

Oil Specs AMSOIL Signature Series vs Mobil 1 Extended Performance

Oil Specifications (from manufacturers) AMSOIL SS 5W-30 Mobil 1 EP 5W-30
Kinematic Viscosity @ 100°C, cSt (ASTM D445) 
Kinematic Viscosity is defined as an oil's resistance to flow and shear due to gravity. At high temperatures, higher viscosity is better and at low temps, lower viscosity is better.
10.3 10.15
Kinematic Viscosity @ 40°C, cSt (ASTM D445)Kinematic Viscosity is defined as an oil's resistance to flow and shear due to gravity. At high temperatures, higher viscosity is better and at low temps, lower viscosity is better. 59.7 58.7
Viscosity Index (ASTM D2270)Viscosity Index measures the variation in kinematic viscosity due to changes in temperature. Higher viscosity index equates to a smaller decrease in kinematic viscosity with increasing temps. 162 163
High-Temperature/High-Shear Viscosity @150°C, 1.0 X 10^6 s.^-1, cP (ASTM D5481)HTHS Viscosity is a measure of a fluid's viscosity at high temperatures and shearing forces. A higher HTHS Viscosity results in improved bearing lubrication and an overall greater level of viscosity protection. 3.11 3
Pour Point, °C(°F) (ASTM D97)Pour Point represents the lowest temperature at which oil flows in a specified lab test. -53(-63) -33(-65)
Flash Point, °C(°F) (ASTM D92)Flash Point is the lowest temperature at which a substance will generate vapors that when exposed to a flame will momentarily ignite and self-extinguish. 220(428) 235(509)
Total Base Number (TBN)TBN measures an oil's ability to neutralize acids formed during engine operation. 12.5 9.2
Cold Crank Viscosity (CCS), cP @ (°C) (ASTM D5293)CCS measures the oil's ability to flow while cranking an engine (simulated) at cold temperatures, the lower the better. 3968(-30) 4930(-30)
Service Life Guarantee 25,000 miles/700 hours/one year 20,000 miles/one year

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.

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.

amsoil and mobil 1 kurt orbahn testing results percent viscosity loss
The Kurt Orbahn Test results comparing AMSOIL Signature Series to Schaeffer's, Lucas Synthetic, Valvoline, Mobil 1 Annual Protection and Pennzoil 5W-30.

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.

astm d5800 testing results showing AMSOIL has the lowest percent weight loss during volatility testing
ASTTM D5800 testing results.

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.

ASTM D2896 Testing results (Total Base Number).

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.

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