Fouled Plugs: The Oil Discussion

Fouled Plugs: The Oil Discussion | RoadRUNNER Motorcycle Touring & Travel Magazine

I’ll save you some time. There’s no such thing as the “oil discussion.” You’re either running the correct oil for your machine that an actual herd of engineers prescribed after applying advanced mathematics, or you’re not. It really is that simple.

Yet, somehow, discussions regarding engine oil have become deeper than the wells from which the commodity is drawn. The term “oil discussion” has even become analogous with utterly pointless rabbit hole debates over the years. Look, it says what type of oil to use in your owner’s manual, clear as day. So why do we still have this seemingly endless river of misinformation on this subject?

There are no doubt many layers to this cake, more than I can write about here. But I’d happily wager that it can be traced back to a lack of understanding regarding motorcycles and the precise engineering that modern engines require. As power and efficiency increase, tolerances decrease. As they do, the machine’s ability to run any oil that’s slick diminishes quickly. High performance engines require high performance fluids. Period.

Regardless of the cause, oil discussions often devolve quickly as everyone chimes in and, like an intravenous drip of poison, the steady injection of anecdotal “evidence” by those with no credentials other than an internet connection begins to corrode the general understanding. Unfortunately, rather than relying on facts and science to guide them through the oily blackness of ignorance, many people take the misinformation they read at face value. It doesn’t have to be this way. Factual information is available from sources other than Joe-Bob from the Facebook group you’re in.

While it’s true that most engines will run a long time with incorrect oil, it’s important to realize that’s a testament to the resilience of the machine, not the dollar-per-quart sludge you found on clearance. Similar to stuffing Big Mac after Big Mac into your face for a lifetime, running out-of-spec fluids will likely be shaving miles off the end of your bike’s life, not the beginning.

But Rotella…

To be clear, I’m not talking about exploring the differences between brands of oil. That’s a completely different discussion. I’m referring to trends such as using cheap oils formulated for cars or heavy-duty trucks in motorcycles. In reality, you’ve only got a couple things to worry about when choosing an oil for any internal combustion engine, and it’s not as complicated as everyone wants it to be.

The first consideration is the weight or thickness of the oil. If you’re using the factory recommended viscosity for the temperatures in which you are operating the engine, you’re good. An incredible amount of work went into determining the tolerances of engine components and the fluid dynamics of the oil. The required properties will have been carefully selected based on complex calculations. Start changing things and you’ll begin to affect efficiency and performance, or—in extreme cases—you might cause oil pressure issues. Find some videos of motorcycle engines seizing at speed to see how much you don’t want that.

Second, there are organizations like the Society of Automotive Engineers, the American Petroleum Institute, and the Japanese Automotive Standards Organization (JASO) that establish quality standards for oils and conduct independent testing. Oil containers will have the ratings it meets or exceeds listed on the back. Over the years, automotive engines and motorcycle engines evolved and diverged and so did their respective oil requirements. The main difference is that most motorcycles use the same oil to lubricate and cool the engine, as well as the clutch plates and transmission. Due to the friction modifiers and detergents added to modern automotive oils, using them can cause clutch slip and damage transmission gears. These issues prompted the founding of JASO in 1998, which established standards specifically for motorcycle oils. Again, the oil requirements for your motorcycle can be found in the owner’s manual.

The third, and arguably most important point, is that the old adage of “the best oil is clean oil” still rings true today. Meaning, the best thing you can do to prolong an engine’s life is to change the oil and filter at specified intervals. Do it more often if you’re operating the engine in extreme conditions.

That’s it. Follow the KISS (keep it simple, stupid) method and trust the professionals who have years of experience in engineering and manufacturing motorcycles. All that said, it sure fouls my plugs right up when people are arrogant enough to think they know more than a manufacturer’s engineering team, race teams, and factory-trained mechanics!


American Petroleum Institute

Blackstone Laboratories