Traditionally, API rated automotive engine oils have been successfully substituted for motorcycle oils, with little or no immediate problems. However, over the long haul, automotive engine oils break down faster in a motorcycle. This is due to the higher rev range of a motorcycle engine, and the fact that an engine oil must also be used to lubricate the transmission and the "wet clutch" design inherent on most modern motorcycles.
Essentially, an automotive engine oil is forced to work harder by doing triple duty lubrication when it was only designed for single duty engine lubrication. This is where a motorcycle oil fills the gap. These oils are specifically designed for the multiple tasks of engine, transmission and wet clutch lubrication. The best of them will maintain their viscosity longer, break down less over a longer period of time and limit metal on metal wear to nearly imperceptible levels.
This list addresses all of those specifications for the best motorcycle oil available.
If you want the best, you go with AMSOIL Synthetic 10W-30 Motorcycle Oil. Although Amsoil makes other viscosities of motorcycle oils, like a straight 60-weight and a 10W-40 weight among others, their 10W-30 weight is the most versatile of the bunch and will work with virtually any motorcycle made. This is a true synthetic motorcycle oil, and synthetic means slippery. The slipperier the oil, the less wear there will be on internal friction parts and the longer the engine will last, period. Because it is so good, you can double the manufacturers drain intervals for engine oil changing. That makes AMSOIL a bit more cost effective over the long run.
There are many scientific tests that will determine just how good a motorcycle oil is. Ss scar testing records the amount of scarring in metal to metal contact under load. NOACK volatility is also a good test, which tests how hot an oil gets before it boils off and no longer lubricates. You can also study the the oil's "total base number," which is used to understand how many wear-causing particles an oil will hold yet still remain effective. In all of these categories, AMSOIL finished at the top.
The reality here is this. Virtually every other motorcycle oil will give your motorcycle superior lubrication over an automotive engine oil. But if you want the best motorcycle oil for your bike, then you want AMSOIL Synthetic 10W-30 Motorcycle Oil. Although it may be difficult to find because it is distributed by independent dealers, there is nothing better than AMSOIL. Read Full Review
For the second best motorcycle oil in this category, here is one that you may be unfamiliar with. It's Red Line 20W/50 MOTORCYCLE OIL. Red Line comes in second to AMSOIL in nearly every engine oil lubrication test there is. Which means that this is an extremely good motorcycle engine oil that will keep your bike running efficiently and powerfully for the life of the engine.
This oil is good enough to stay in your bike for extended drain intervals. It just doesn't break down as fast as a conventional motor oil, and that makes it a bit more cost effective to use. There are several different viscosities of Red Line, but the 20W-50 is the most versatile and will work in virtually every bike made.
If you like the underdog here, then consider using Red Line 20W-50 Motorcycle Oil in your bike engine. It's the best motorcycle oil at this party, as long as AMSOIL doesn't show up. Read Full Review
If you are traditionalist and like regular non-synthetic motorcycle oil, then Pro Honda GN4 4-Stroke Motor Oil 10W-30 is the one for you. This is one of the non-synthetic oils that compares favorably with the highest rated synthetic brands out there. Granted, it doesn't give the protection that a synthetic does, it isn't as slippery as a synthetic, and it will need to be changed at manufacturers recommended intervals. But, this is still an incredibly good oil for any motorcycle engine and it rates high on this list.
The best part about Honda GN-4 is that is costs about half as much as the top rated synthetic blends. So it won't break your bank account every time you use it. And since it is a 10W-30 weight engine oil, it will work in virtually every motorcycle engine made. Many bikers of all types swear by this stuff, even though it isn't a synthetic and isn't as highly rated. Make no mistake about it, this is a true high-quality motorcycle engine oil that will keep your engine running clean and mean for the duration.
Even though this is a non-synthetic formula, you won't sacrifice quality when using Pro Honda GN-4 Motorcycle Oil. Yes, it's that good. Read Full Review
Next on the list is another conventional formula called Maxum Maxima Racing Oil Premium 5W-30 Weight, Motorcycle Specific Motor Oil. This is another regular type of motorcycle oil that compares favorably with the slipperier synthetic oils in this list.
It rates slightly below the Honda non-synthetic engine oil, but that doesn't mean Maxum is an inferior product. It will work well with virtually any motorcycle engine to give you the power, efficiency and longevity that you would expect in a conventional type of oil.
Maxum 5W-30 weight oil will cost about half as much as a synthetic, although it isn't as durable and will need to be changed according to the intervals suggested by the motorcycle manufacturer. However, as long as those intervals are followed, Maxum Motorcycle Specific motor oil will be there for the life of your motorcycle engine. Read Full Review
Arguably the best synthetic motor oil for your car or truck, Mobil 1 94001 Synthetic 5W-30 Motor Oil also makes a darn fine motorcycle oil for your bike engine. Mobil 1 synthetic will be the easiest motor oil to find for your motorcycle needs, yet it will cost a bit less than the top grade of synthetic motorcycle oils out there.
Regardless of the fact that it is made for automotive and truck use, it is still a synthetic motor oil and it will give any bike engine all of those synthetic properties. That means it will reduce wear and friction while slightly increasing gas mileage and performance.
Although not a true motorcycle engine oil, many people use this in their bikes and will use nothing else. Couple that with the aforementioned price compared to strictly synthetic motorcycle oils, then add in the fact that it's available almost everywhere, and that makes Mobil 1 Synthetic Engine Oil one of the best engine oils to use in your bike. Read Full Review