What Motor Oil Should You Use?

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Revision as of 12:54, 13 March 2007 by Pi3832 (talk | contribs) (API Grade)
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Never has there been an issue as hotly debated as what motor oil to use in a motorcycle. Forget helmet use, forget brand-loyalty, forget counter-steering. If you want to see an inflammed ruckus with much YELLING and many exclamation points!!!!!! ask about motor oil in a motorcycle forum.

It seems like such a simple question. And perhaps there is a simple answer: Use the motor oil that you feel meets your needs.

But how do you decide which motor oil that is?


You're going to have to do a little research. Do some reading. It'd be nice if there was some resource that simply said for motorcycle XYZ, use motor oil brand ABC in grade 123. And you may find one that does, but that resource will invariably have been at least sponsored, if not directly written, by the folks who make and sell motor oil brand ABC in grade 123. Shocking.

Owner's Manual

The first thing to read is the owner's manual for your motorcycle. If you don't have one, get one. You can buy owner's manuals from:

  1. Your local authorized dealer
  2. An online vendor of OEM parts
  3. Helm, Inc. if you're looking for a Honda manual
  4. Or even eBay, if you're brave enough

The owner's manual is written by the people who know your motorcycle's innards the best, and who have a vested interest in it living a trouble-free life. (Yes, you'll buy a new bike sooner if your old bike dies young--but will you buy the same, short-lived, brand again?)

What you'll find in the owner's manual is the minimum API grade of oil to use, and a variety of weights to choose from, depending on the conditions under which you'll be riding.

This is your starting point. Don't use a motor that doesn't meet the specifications listed in the owner's manual. There's really no reason to, since there are a vast array of motor oils to choose from that will meet those requirements.

API Grade

Do NOT use this oil in your motorcycle.

To the right you'll see an example of the API Service Symbol, also known as the API donut. This is on most bottles of motor oil sold in the U.S. If it isn't on the bottle, that means the oil has not been certified to meet API standards.

The API donut tells you three things:

  1. API Service and Grade
  2. SAE weight
  3. Whether the oil is "Energy Conserving"

This label is controlled by the API. Manufacturers are required to submit samples of their oil for testing by independent (from the manufacturer) labs to certify that the oil really does meet the requirements to carry the API donut, and what that donut says.

The API publishes a pamphlet explaining the donut.

Energy Conserving motor oil will increase a vehicle's mileage. However, the common wisdom in the motorcycling community is that the additives used to achieve this higher mileage is detrimental to a wet clutch, which most motorcycles sold in the U.S. have.

There is no objective evidence to support this notion. But, there are plenty of oils that are not rated "Energy Conserving," so it's probably best to err on the side of caution and not use "Energy Conserving" motor oils. Plus, it's mostly a non-issue. The vast majority of such oils are 5W-30 weight, and few if any motorcycles use that low of a weight of oil.

The API Service is the first letter of the code in the top of the donut.

  • "S" - gasoline service
  • "C" - diesel service

The subsequent letters give the particula grade of the service that the oil meets.

For gasoline service, the grades are assigned alphabetically, and any grade meets all of the previous grade's requirements. Thus, service and grade "SJ" meets all of the requirements for grades SH, SG, SF, etc. (Some letters were intentional skipped by API.)

The diesel grades are more complicated, as there are different kinds of diesel service, such as "severe duty, high speed, four-stroke engines using fuel with less than 0.5% weight sulfur" as opposed to "severe duty, two-stroke cycle engines."

Mark Lawrence has put together a nice summary of the various API grades on this webpage.

Your owner's manual will tell you the minimum API service and grade you need to use in your motorcycle.

But perhaps you want to go above and beyond the minimum requirements? See the More Information section below.

SAE Weight

The API donut also tells you the SAE weight of the motor oil.