Motorcyclists can debate oil like some people debate baseball teams and player stats. 10w40 versus 20w50. Synthetic ester versus conventional. But is there really a difference besides marketing and prices? You bet.
To be clear, you should always go with the oil your owner’s manual says you should use. Which kind of oil you should use depends entirely upon what kind of riding you do. Sunset cruisers’ and flat track racers’ bikes perform dramatically different functions, and thus have vastly different needs. Thankfully, there’s an oil designed to satisfy every type of rider.
As your engine’s lifeblood, oil serves multiple purposes. Primarily, it lubricates the internals and helps keep the engine’s temperature stable to ensure that your engine runs smoothly while you’re out enjoying your favorite road. But what makes some oils better at it than others?
First, it’s important to understand the composition of engine oil. “Oil” is a bit of a misnomer: when you buy a quart of oil, you aren’t just buying oil: you’re buying a blend of oil and chemical additives. Typically, a quart of oil is 75-80% base stock, and 20-25% additives. The base is the oil itself, which comes in two types: mineral (also known as “conventional”) and synthetic. Mineral oil is refined crude oil that’s been pumped out of the ground, and synthetic oil is oil that has been synthesized in a laboratory. The additives include anti-wear agents that improve lubricity by controlling viscosity, contaminant control, chemical breakdown control, and seal conditioning. Together, the base and additives make up the engine oil that keeps your motor alive.
What’s the difference between mineral and synthetic oil, besides the obvious? Simply put, mineral oil is less chemically pure than synthetic oil, which means that it’s less stable. Synthetic oil is very chemically pure, which means that it’s very stable, and esters are the purest synthetic oils of all. Semi-synthetic oils are a blend of mineral and synthetic oil. The more stable an oil is, the better it is at preventing wear and tear in your engine, and the more resistant it is to breaking down during extreme use. Because the finished product is significantly more difficult to produce, synthetic oil is more expensive than mineral oil.
What’s the right oil for my bike? If you’re like most of us, you enjoy just taking your bike out for a regular cruise. Mineral or semi-synthetic oil would serve your needs just fine depending on the mileage. If you consider yourself a high performance rider and take your bike to the local dirt track or do battle in the canyons every weekend, you may want to consider running synthetic oil. Some mechanics recommend using mineral oil to help break the engine in since it doesn’t resist engine wear as much, and then either semi- or full synthetic oil once the engine has been fully broken in due to its anti-wear properties.
What’s the other type of oil mean, the SAE one with the “w” in it? Oil comes in “weights,” which refers to how viscous the oil will be at different temperatures. Oil, like most other liquids, thickens as the temperature drops. What this means for is that the colder it is outside, the harder it is for the oil to flow through your engine. Motorcycles typically use 10w40 oil, which means it will work for your engine under most non-extreme temperatures. However, you should refer to your bike’s owner’s manual to figure out exactly what kind of oil is recommended for your model, or call your local dealer and ask what kind of oil they suggest using depending on your climate.
As with everything about motorcycles, it’s different strokes for different folks. Choose an oil that’s right for your needs and climate to extend your engine’s life as well as to help make sure you’re paying for what you need and not what some talking head on YouTube thinks is the greatest thing of all time. Lastly, buy the best oil your budget allows for. If you paid $10,000 for your bike, don’t let its engine go to shit because you wanted to save $10 twice a year by buying cheap oil. Rebuilding or replacing the engine is a helluva lot more expensive than buying quality oil. Protect your investment and keep your baby running strong by using the best oil you can buy of the type your bike specifically needs, and change your oil at the intervals recommended by your owner’s manual.