AMSOIL vs. Mobil 1: How We Perform

Enthusiasts love to modify their vehicles to make more power. Lists of top-10 mods often include nitrous, a performance exhaust, an engine tune, upgraded intake and more. But they never include upgrading your motor oil to handle all that power. Let’s look at why you should upgrade your oil – and how two of the best available stack up: AMSOIL vs Mobil 1.

Heather K BRZ Engine

Horsepower riding on a sheet of paper

Your engine – and the time, money and effort you’ve poured into it – rely on an oil film that’s thinner than a sheet of paper. 

Adding horsepower increases rpm and engine stress, placing even more stress on the oil. Many enthusiasts make compensatory upgrades to the crank, pistons, cam and bearings to handle the additional pressure.

The shear importance of oil 

In this scenario, upgrading the motor oil is often overlooked.

But it’s an important consideration since engine upgrades can increase shearing forces, which result in viscosity loss. And viscosity is the most important property of oil.

Find out: What Does Viscosity Mean (and How Does it Affect Your Engine)?

Viscosity breakdown, AMSOIL, Mobil 1, 46% better
Shear results when one layer of fluid moves in a direction different from another layer of the same fluid.

Shear (often called mechanical shear) occurs when one layer of oil moves in the opposite direction of another layer of the same oil.

A great example occurs between the piston and cylinder wall. These two oil films move in opposite directions under intense heat and pressure. This is why high-horsepower, high-rpm engines create increased possibility for viscosity loss due to shear.

This scenario can shear, or tear apart, the molecules of viscosity-improver additives, which are used to extend the viscosity range of the base oil. The application and type of base oil determine the type of viscosity improver. Some viscosity improvers resist shear better than others. And some synthetic oils don’t need viscosity improvers at all due to their ability to withstand shear.

If the oil loses viscosity due to shear, it can fail to provide the required level of wear protection. Think of the force transferred through the piston, rod and crank to the thin oil film protecting the bearing. There’s not much room for error.

AMSOIL vs Mobil 1: The results

AMSOIL uses naturally shear-resistant base oils combined with top-tier, shear-stable viscosity improvers. AMSOIL synthetic motor oil withstands extreme heat and shearing forces, exceeding industry standards and outperforming competing brands. In fact, it fights viscosity breakdown 46 percent better than Mobil 1. It stands up to the devastating effects of high-horsepower, modern engines for maximum protection.

AMSOIL also does a better job resisting volatility, which refers to an oil’s tendency to evaporate in the presence of extreme heat. Powerful forced-induction engines modified to shred the pavement make intense heat, which can cause inferior oils to breakdown, creating harmful engine deposits that reduce performance.

Here again in the AMSOIL vs Mobil 1 debate, AMSOIL comes out on top, fighting volatility 38% better.

How about engine cleanliness? A clean engine is a more efficient, longer-lasting engine. And, after pouring your time and hard-earned money into your vehicle, you expect it to last.

An oil’s total base number (TBN) is a measure of its ability to neutralize harmful acids that lead to engine deposits. When we pit AMSOIL vs Mobil 1 in TBN testing, AMSOIL delivers 28% more acid-neutralizing power than Mobil 1 to help your engine stay cleaner, longer.

To be sure, Mobil 1 is a good motor oil. If you’ve upgraded to Mobil 1 from conventional oil, congratulations on choosing better engine protection.

But, as the results of industry testing show, AMSOIL Signature Series Synthetic Motor Oil emerges victorious in the AMSOIL vs Mobil 1 debate. Give your engine the best protection you can – give it AMSOIL synthetic motor oil.

Updated. Originally published Jan. 16, 2019.


  1. It seems to me that these tests should be tested in the real driving reality of all driving conditions in different states. Take West Virginia, that has hills, slopes & NOT many flat land surfaces where roads are built on hillsides & mountain terrians., compared to Delaware, over 90% all flat earth roads & you can be in different climates between the 2 states. Any lab testing room for anything, will give a FALSE report on anything, when compared to actual reality STRESS & WEAR & TEAR of an engine, transmission & performances of any engine no matter how many cylinders & HP it has. GAS quality makes a difference also between states in different areas of the country. There is a difference between gas sold in the North East compared to the Mid Atlantic & Mountain areas of the country. So any tests results from any lab does not come close to reality, as the BIG 3 & others always say how much better MPG’s they have, & they use LABS to get those FALSE numbers.

  2. I was sold on Amsoil about 15 years ago. I had no idea how good it was until I started using it. I’ve pulled the heads off my 175,000 mile Ford Windstar engine and the cylinders had virtually no wear. Lots of independent you tube videos comparing other oils to Amsoil and Amsoil always comes out on top. At a recent Rally, Mobil 1 had their booth set up. I talked to the Representative about Mobil 1 vs Amsoil. He admitted that Amsoil was better than Mobil 1. I use all their products in all my vehicle engines, transmissions, differentials, etc and I know that any lubrication problems will be almost nill. So I thought the best way to be an Ambassador for their products, Is to be an Amsoil Dealer.

  3. This is in response to a comment made by “Ryan on Sept.12,2019 at 2:46pm”. In his Blog, he states “they(referring to Amsoil filters) are made in Europe by the number one filter maker in the world”. ?????
    I have just ordered and received, Amsoil oil filter EA15K37 (for my 2012 Jeep Wrangler Sahara) and printed on the box and on the filter it says “MADE IN CHINA”. One question I have is, where did Ryan get the info that Amsoil filters were made in Europe? The other question I have is why, with all the hype that Amsoil products are made(produced) and packaged in the USA, are they selling oil filters made in CHINA??
    Thank you for your time and any response you may have.
    Mike J.

    1. Hi Mike,

      Most of our filters are made in the U.S. It is true that a handful of our cartridge filters are made in China. But, we are handcuffed. Our U.S. filtration partners cannot make these filters with our proprietary media built to our strict quality standards – their manufacturing equipment is not compatible with our media. In order to offer our filtration technology for these few applications, we have to outsource them to Asian partners. It’s either that or don’t offer filters for those vehicles, or compromise on the quality and performance of our filtration media to make it compatible with U.S. manufacturers’ facilities. We do not compromise on quality or performance.

      We are proud to make our products in the USA and provide American jobs. Unfortunately, continual consolidation in today’s global economy means that in a minority of cases, we can’t get what we need domestically. You can rest assured that we will always choose American options first, and you can also be confident that the filters we offer that are manufactured in China are manufactured to our quality standards and deliver the performance you’ve come to expect from an AMSOIL filter.



  4. I’ve been using AMSOIL Signature Series 5w30 engine, AMSOIl ATF Transmission, AMSOIL gear Differential in my 2006 supercharged mustang (675hp) with great results… The issue I have is the AMSOIL filter that is 98.7% efficient vs MOBIL 1 @ 99% given the price.. Actually STP top filter @ $8.00 is also 99% efficient… So I might change filters, but will stay with AMSOIL oils….

    1. Hi Aksel,

      Thanks for using AMSOIL products; we’re happy to hear about your positive results.

      As for our filters, after recent testing, we’ve upped our efficiency claim to 99 percent at 20 microns. When comparing filter performance, make sure you note the percentage efficiency at the given micron size. While competitive filters also claim 99 percent efficiency, they may do so at 30 or 40 microns.



    2. Amsoil filters are light-years ahead of over the counter filters buddy they are made in Europe by the number one filter maker in the world you can stamp whatever percentage factor you want on a filter but when you actually pull the micron rating and lifespan of the filter that is specifically made for use with amsoil synthetic your messing up if you change… The level of protection you get using amsoil is off the charts have a 00 f350 with 596k original 7.3 engine chipped and maxed out way more torque and power than the mustang under load and if it’s moving it’s loaded work truck hotshot and farm truck… In diesel shop at local college they take my truck apart and put back together twice a year completely have done since new free service parts not included for kids to learn… In the most recent break apart had them mic every wear point to factory spec no bs happy to mail you the information photos ect no buildup no visible wear and absolutely no oil use engine is all original and per instructor of the international training school expert is the cleanest best looking engine he’s ever seen with that kinda miles said it was comparable to one with 50-75k… Amsoil has open door clear third party and in house testing and is extremely well documented try research on those other over the counter filters and see where they get those hard numbers from… GMC recommended the very penzoil to keep my warranty on Z71 listed here on this post look at amsoil 293k pushing over 500hp no oil use all original parts besides the mods and chip I did to make the horsepower when bought…

    1. Hi Daniel,

      We selected a cross-section of oils to represent the choices confronting customers when they buy oil. For that reason, we selected synthetics and conventional oils against which to compare.



  5. AMSOIL won’t state if it’s PAO, won’t submit to real world based testing in applications that matter to the consumer. I’m not going to buy a case of AMSOIL and run it through tests on a bench. I want to see the wear that actually occurs from two engines using AMSOIL and Mobil 1 before I can believe these claims. If your claims are true, this would be evident from tests such as these and you would pick up a much larger customer base in demonstrating this. Why does AMSOIL seem to retreat if their product is superior?

    1. Hi Mark,

      Thank you for your consideration of AMSOIL and your questions. Like the rest of the industry, AMSOIL formulations are proprietary. Having said that, we use a robust slate of synthetic base oils, which includes PAOs. As you may already know, base oils are only one part of the equation. The type, mix and amount of additives has a profound affect on that oil’s ability to protect against wear, sludge and corrosion. Our additive package composition is unique to AMSOIL and delivers protection that goes far beyond industry standards and leading brands. You make a great point about real-world engine testing. For most serious enthusiasts, professional engine builders are the gold standard for engine testing. AMSOIL has earned the trust of top engine builders like Barry Robotnick, Daniel Boshears and Brett Bowers.



  6. So, we all assume that Mobil 1 Syn (regular) performed better than Amsoil in this test. If Amsoil had outperformed it, I’m sure it would be on the chart…

    1. Hi Steve,

      One of our criteria for creating comparisons is to ensure we include representative brands within each motor oil category. With that in mind, we chose Mobil 1 Annual Protection because the manufacturer positions it as “the ultimate full synthetic motor oil.” That being the case, we did not test Mobil 1 Synthetic Motor Oil.



  7. The results of the Kurt Orbahn Test are merely a theoretical indicator of the viscosity loss due to shear at the injector nozzle, since it is a bench test that does not involve an actual engine.

    1. Hi Nightflight,

      The industry recognizes bench tests, including the Kurt Orbahn Test, as useful tools for evaluating motor oil performance because they remove certain variables and allow evaluation of specific oil characteristics. Bench tests also allow formulators to screen oils before investing the great deal of resources needed to subject them to rigorous field tests. That’s why we, and just about every other oil company, use them to evaluate motor oils. That being said, we also rely on field tests to determine oil performance, and you can read about some of them here:



    1. Hi Joe,

      The graph depicts results in the Kurt Orbahn Test (ASTM D6278). It was performed in an independent, third-party lab. It’s a bench test, not an engine test.



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