I think this is worth posting here. The Editor likes to take lengthy, often imponderable issues down to the core. I like this:
The Final Word On Oil, Finally
Editor, OTL Magazine
I know a fellow with 250,000 miles on his Honda VFR750. He’s always used Castrol 20w50 “car” oil. So why do they make motorcycle specific oils? What kind of oil do you use? Why do you use it? Are there still some unanswered questions in your educated mind? Here we go then. The online forums are usually useless, questions being answered by faceless self- proclaimed “experts” we’ll never meet. Lots of prejudice there. It all boils down to synthetic vs. conventional oils. What’s the difference and what’s the best for your motorcycle? Both oils contain base oils and additives. Interestingly, base oils are as clear as water. The additives give it color. Oil has to resist heat, resist thinning, resist chemical breakdown, and maintain fluidity at cold temperatures. Additives provide the performance not provided by the base oils. Additives are expensive. The manufacturers swear the motorcycle specific oils are best for your bike. Their additives are engineered for the punishment we dish out to our engines, and motorcycle engines take a real beating. The racing guru I always go to for mechanical clarity uses Mobil One synthetic “car” oil. The 2006 8 Hours of Daytona (BMW R1200S boxer) was won on Mobil One oil purchased at WalMart, but keep it to yourself.
Refined oil from crude comes from the ground as a thick, stinky, sulfurous, waxy mess. We all know engine wear is most damaging at start up, when the oil has drained off critical moving parts, like piston rings. Impurity contamination demands oil changes at specific intervals. Conventional oils also break down quicker than synthetics do. So how do we get the oil we use? By separating the crude oil into “fractions” such as gasoline, LP gas, kerosene, and base oil. Conventional oil is inconsistent molecularly, having impurities that reduce performance. Conventional oil can volatize, or boil off, leaving you low on oil even though you don’t leak nor apparently burn it in your engine. This is most apparent in air cooled engines in the summer. Some is exhausted as emissions. Some volatizes as deposits on engine parts. I’m always adding oil to my own R1200GS, yet it doesn’t leak a drop nor burn oil either. Volitization makes sense. I’m switching to synthetic at the 18,000 mile scheduled oil change. I figure that’s enough time for the engine to break in. My dealer told me to “just ride the #xit out of it” and so I do.
Viscosity is critical, and conventional oils are prone to shearing the molecular structure of the lubricant, slowly destroying it. Synthetics are more uniform molecularly, and synthetics are more highly refined in the base oil stage. So, synthetics are better able to resist this shearing destruction. Synthetics simply perform better, and their more intense refining process is way more expensive. Heat and shearing are the enemy. Synthetics reduce friction better than conventional oils. They can even increase fuel efficiency and power output. Synthetic “blend” oils are also inferior to full synthetics. They may be a cost-saving marketing ploy for all I know. Synthetics are probably the least costly investment you can make in your motorcycle. I’ve been waiting to change from conventional to synthetic in my own Boxer. Now’s the time. I’m buying my synthetic oil at the BMW dealer, because I’m tired of thinking about oil! There you have it.