Here’s Why Oil Additives Are Bad For Your Engine

Cars need motor oil like human beings need blood. That’s why our dad always told us to keep up with our oil changes when we had our first car. Like any other aspect of automotive maintenance, there are certain do’s and don’ts to ensuring your vehicle has a healthy oil life. The most common “do” for modern cars is changing their oil every six months or 5,000 miles, whichever comes first. 

Some car owners like using oil additives to bolster their engines and extend their oil life. While many believe oil additives can help clean deposits out of their engine to prevent wear, a recent real-world test shows that oil additives will do more harm than good to car engines.

The Test 

These YouTuber The Motor Oil Geek tests show that oil additives can potentially damage car engines. The host, whose real name is Lake Speed Jr., was an integral part of creating Joe Gibbs Driven Racing Oil, meaning he’s the epitome of what it means to be an expert in car oil. 

Speed Jr. picked out popular oil additive brands that car owners can commonly find in any auto parts store, such as Marvel Mystery Oil, Lucas Stabilizer, Rislone ZDDP Supplement, and Seafoam oil treatment, to see how they interacted with PAO base oil when he mixed them. The results make it abundantly clear that anyone considering adding something to their oil should STOP doing so immediately.     

How Oil Works 

According to Speed Jr., fuel and motor oil additives do not have to meet API or OEM specifications like motor oil. Just because you can find them in a bottle on an auto parts store shelf doesn’t mean auto industry experts have vetted a product to ensure it meets their specifications. Per the instructions on each additive’s container, Speed Jr. mixed 1.5 ounces of each with 1 quart of base oil to see what each product would add to the oil for his test. 

Before sharing any lab results from his test, Speed Jr. gave a succinct explanation of how motor oil works and why mixing additives to it can be very problematic: “The reality is that motor oils are already a complex mixture. There can be 14 different chemicals in one motor oil, and when you add another chemical or three or four, I don’t know how many to that mix. Sometimes it could go good, and sometimes it could go bad. It’s basically chemical Russian roulette with your engine whenever you put an additive into your oil base oil.”  

Frothy Mixtures And Financial Incentives  

After adding several additives with base motor oil and mixing them with a frother, they were all very frothy, which Speed Jr. was not enthusiastic about. That description also pertains to ExxonMobile’s SpectraSyn Max 3.5 lubricant, which Speed Jr. states Red Bull uses on their Formula 1 race cars.

Speed Jr. shared his thoughts on why oil additives are so prevalent on auto parts store shelves when they do not meet OEM or API specifications, and it comes down to a matter of dollars and cents, “When you sell additives, you make more money. It’s just that simple. There are some additives that sell for three times the amount of money compared to even a premium motor oil. So, the next time you see an additive being marketed, just know that there’s a heavy financial incentive to say additives are better than motor oils by themselves. Of course, my thought is that if you have to put an additive in your oil, it means you have the wrong oil.”

The Importance of Polyetheramine 

According to Speed Jr., the only good additives are fuel additives, and the additive’s brand is not a quality measure. What matters is that the fuel additive contains Polyetheramine, which Speed Jr describes as a detergent additive that cleans fuel injectors and combustion chamber deposits. 

The problem with dirty fuel injectors, according to Speed Jr., is that fuel atomization tends to be very poor, which increases fuel dilution. According to Speed Jr., higher fuel dilution leads to more significant engine wear, so there are suitable additives for car owners to use to reduce wear on their engines.   

Lab Results 

After performing an oxidation test on two very popular additives, Marvel Mystery Oil and Lucas Oil Stabilizer, Speed Jr. found that both products created imbalances in the oil, shortening its life, which can lead to more deposits forming in the engine. 

We’d be remiss if we didn’t add that those oxidation results for Marvel Mystery Oil and Lucas Oil Stabilizer are what Speed Jr. said were the “bad” results; however, the test results for some of the other additives were “ugly” in Speed Jr.’s words. The frothy Seafoam mixture, in particular, did not test well. According to Speed Jr., the mixture will evaporate as soon as someone pours it into their engine oil; it will also suck in water, which is never a good thing for a car engine.

He cited the additive Oil Extreme as one of the worst products, especially for direct injection engines. Speed Jr. said it could destroy an engine because its sodium and calcium levels can lead to low-speed pre-ignition. Speed Jr. emphatically summed up these results for anyone struggling with some of his technical jargon when he said, “Putting an additive in your oil compromises the life of your oil.”