Is 20,000 Mile ‘Annual’ Oil Really Up To the Task? Let’s Take a Look.

Additives are the key to long life oil, but how do parts hold up after 20,000 miles of abuse?

If you’re a skeptic of those oils that tout ridiculously high oil life, you’re not alone. You’ve probably seen the Mobil 1 advertisement calling it “annual protection,” claiming it lasts nearly four times longer than your standard oil change intervals. But oil is oil, right? It heats up, it cools down, it gets dirty and brakes down, and dirty oil is a quick demise for a high performance engine. So what is different about annual protection oils?

Testing an oil like this is a very thorough process, and developments on new oils do not come about by accident. As Jason Fenske from Engineering Explained points out,”Marketing does their research to determine what product they want to develop, and they find out from the engineering team if they can make an oil that lasts 20,000 miles.” Given that particular task, the engineers at Mobil 1 then set out to figure out what additives are needed to make a long-lasting oil.

Those additives are the key part of the longevity. Surface layer additives do the main protection, but other additives keep the oil from getting too thin, and keep the oil from foaming. Other additives keep engine parts from oxidizing, and additional additives are meant to carry contaminants so they can be filtered out and not deposited elsewhere. But before they know if a combination will work, it needs to be tested.

Before actually testing the oil in a car, preliminary testing is done on a rig to super-heat the oil, and test for the parameters it needs to meet. Fenske tells us that “the test requires a stainless steel rod, and oil flows around it.” Essentially, that rod would simulate an engine part which may get sludge and oil deposits. If the oil passes this test, it’s on to an engine dyno and further a rolling road with a car.

On the rolling road dynos, several different style cars are used, just for a variety of engines. Turbocharged cars are becoming more and more common, and their oil systems are specifically catered to those turbochargers, placing an extra demand on the oil. Cars are run on engine dynos for 20,000 miles, the oil and filter is changed, and that interval is repeated 6 times. Fenske says, “After the 120,000 mile stints are complete, there’s a visual inspection of the entire engine. The engine is completely torn down and compared against industry standards.” That tear down is a blind test as well, with the technicians not knowing what type of oil was used. If there’s a flaw of any sort, it’s going to be found.

So, seeing as these tests are extremely thorough, would you still trust an annual oil? We know Mobil 1 is the factory recommended oil for Corvettes, but maybe for your daily driver a once-a-year oil change is a reality.

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