The Original Easyrider®
Motorcycle Oil Analysis
Facts, fiction and folklore
White Paper

When it comes to motorcycles, it seems like everyone who owns one has an opinion on tires and motor oil. Some swear by a specific type or brand and others wouldn't use a particular product if their life depended on it. So what's behind this fierce brand loyalty?

Many of the people I've talked to like and stick with a particular product because "it's worked well for them over the years". No problems = it's a great product. But... the fact is that any high quality oil formulated for motorcycle use will most likely not cause any problems, especially if the manufacturer's drain interval recommendations are followed. In fact, if there was a motor oil in the $10+ per quart price range that was damaging motorcycle engines, the company that makes it wouldn't be in business for very long, right?

Another thing I hear a lot is, "I would never use product X, because....". Often, the "because" has nothing to do with the brand or type of oil per se. For example, owners of older motorcycles often complain that switching from conventional to synthetic "caused their o-rings and seals to leak"... when, in fact, the o-rings and seals were already worn and in bad shape... it's just that the gunk that was caked on them helped "seal" the cracks. Using a high quality synthetic "washed away" the crap from around the o-rings and seals so all of a sudden, the owner starts seeing leaks. So using a synthetic took the hit when the real problem was a motor that needed new seals and o-rings!

Suffice it to say that there is a lot of unsubstantiated opinion, myth and folklore involved in any of these "oil quality" discussions. So what's really needed to figure out what's real and what isn't? An actual used oil analysis!

If you aren't doing some sort of thin layer chromatography (TLC) or other labratory analysis on your motorcycle lubricants when you drain them, you may not actually know what you are talking about when you spout off your opinions of the topic. An exception would be someone who regularly tears down motorcycle engines and sees first hand the damage (or lack of) caused by inferior oil or lubricating methods. But this statement would not apply to lubricants that are designed specifically for racing use. Most street bikes these days can go 100,000 miles without any serious engine maintenance whereas racing oil formulations ASSUME that the motor will be torn down frequently. So.... don't be using race formulated motor oil in bikes that will go decades without seeing the inside of a shop!

You can generally never go wrong by following the manufacturer's recommendations and nothing we post here should be construed as contradicting what any manufacturer says. This is not the same as manufacturers "recommending" their brand of lubricant solely due to marketing reasons. By manufacturer's recommendations, we mean adhering to the requirements listed in your owners manual with regard to viscosity, product formulation compliance and drain intervals. We do not mean self-serving statements such as "ABC Motorcycle Company recommends that ONLY ABC Motorcycle Company lubricants should be used in your motorcycle" or any such thing.

As far as motor oil is concerned, any JASO MA2 synthetic of the proper weight will be perfectly fine in any 4 stroke, street motorcycle manufactured in the 21st century.

For general service, Harley Davidsons typically run 20W-50 and most metrics specify 10W-40. It's not particularly important whether you use conventional or synthetic oil although some manufacturers still specify conventional or semi synthetic use until the motor is broken in. Synthetics have several advantages over conventional lubricants and no real down side except for the additional cost. Contrary to popular myth, you can go back and forth from conventional to synthetic with no adverse effects. You are more likely to have problems if you constantly change brands since each oil company uses a different formula when blending their lubricants.

Therefore, it's generally not a good idea to "top off" your crankcase with a brand that's different than what's already in the bike. The reasons I've read that support this advice make sense to me. However, it is also recommended that if you do top off using a different brand of oil, the oil in your motorcycle should be dumped and changed as soon as possible. This piece sounds like bunk to me, unless you are going to run many thousands of miles further before doing an oil change. My reasons? When you change your oil, there is always going to be some old oil left in the oil lines, the bottom of the sump and so on. So while I would agree that frequently changing brands is not a good idea, dumping the oil just because you topped it off with something else seems like overkill to me. Especially if you only used a pint or so in the topping off process. IMHO, if you are consuming more than a quart of oil between 3,000 mile oil changes, you've got more serious problems than possibly "contaminated" oil!

AN IMPORTANT NOTE THOUGH: is that you should not use car oil in a motorcycle!

If the car oil is JASO MA2 compliant, you will be ok putting it in your bike (as a motor oil lubricant). I ran Pennzoil car motor oil in my pans, shovels and even my ironhead Sportster for decades. While I am not recommending this practice today, I'm simply saying that I never had a problem in the past doing so.

But metrics and motorcycles that lubricate the clutch with the same oil that's in the motor crankcase is a whole different story! You do not want to use a lubricant that has "friction modifiers" or "energy saving" properties in these bikes. But again, if the oil package says "Motorcycle oil" and if it is JASO MA2 compliant, or even only has a service designation of CF, CG, CH, CI or CJ compliant it is most likely going to be just fine. But ALWAYS consult your owners manual before making any changes to what the Dealership uses in your year and model motorcycle!

NOTE TO HARLEY OWNERS: According to Harley Dealerships that I've talked to, Screaming Eagle SYN3 oil is perfectly acceptable as a motor oil for pretty much any Harley Davidson still on the roads. Opinions on what should be used in older (pre twin cam) Harley transmissions and primaries varies depending on who you talk to, so once again, I'd stick with what's in the owners manual. Interestingly enough, the Harley Davidson Screaming Eagle SYN3 oil container says nothing about it's lubrication industry compliance level. It simply says that it's a proprietary product of Harley Davidson. My [2010 FXSTC] Harley Owners manual says, "If it is necessary to add oil and Harley Davidson oil is not available, use an oil certified for diesel engines. Acceptable diesel engine oil designations include CF-4, CG-4, CH-4 and CI-4. The preferred viscosities for the diesel engine oils in descending order are: 20W-50, 15W-40 and 10W-40. At the first opportunity, see an authorized dealer to change back to 100 percent Harley-Davidson oil."

My comments on the above: As stated previously in this "white paper", mixing ANY brand of oil when topping off is a bad idea although less harmful than running your motorcycle with a low oil level. Harley Davidson seems to be implying that putting diesel rated motor oil in a Harley is "undesirable" versus saying that mixing ANY motor oil in ANY engine is undesirable. We believe that the latter statement is the more accurate one. And in particular, we believe that the instruction to change back to "100% Harley oil" is misleading at best and is probably more about marketing and sales than it is about technical or reliability problems that would result in using a non-Harley Davidson packaged lubricant. With all due respect to the Motor Company, IMHO it would be more accurate to advise draining the oil at the earliest convenience and replace it with ANY comparable brand of oil, of the proper (20W-50) viscosity.

I've read nothing from Harley Davidson that says that running a high quality non-Harley Davidson 20W-50 CF-4, CG-4, CH-4, CI-4 or better oil will in any way harm the motor and/or void the warranty. Not that I am trying to sell or promote a particular lubricant, but AMSOIL 20W-50 synthetic motorcycle oil F-A-R exceeds Harley Davidson's specifications for acceptable motor oil.

Note that 20W-50 SYN3 is not recommended for use in ambient temperatures lower than 40 degrees F. For ambient temperatures lower than that, the Harley owners manual recommends H-D multi-grade 10W-40 which I believe is a conventional "dino" oil. Seriously... talk about covering your butt!!!! 40 degrees F isn't exacty Antartica! Here in Portland, Oregon, I ride all year round and it frequently gets into the 20's and sometimes even the teens during the Winter. So I'm supposed to dump my wonderful, expensive SYN3 synthetic for a few months and replace it with H-D Multi-grade 10W-40 (but not something better like Rotella T-6 5W-40 synthetic)?!?!!? And their reasoning behind these recommendations is:....?

For clarification: an oil labeled as 10W-40 must pass the SAE J300 viscosity grade requirement for both 10W and 40, and all limitations placed on the viscosity grades (for example, a 10W-40 oil must *FAIL* the J300 requirements at 5W)! So.... if you're going to be out and about on your Harley Davidson in the cold, wouldn't a 5W-40 synthetic be better than 10W-40?

My personal experience: I lived in Northern New Hampshire for many years and rode all year round. With temperatures commonly below zero F up there, I considered 20W-50 to be "slightly" too thick for that environment. Note that in those days, running straight SAE 50W in a Harley was considered the norm. I would think that running Rotella T-6 5W-40 (CJ-4 certified) would be just fine and probably much preferable to 20W-50. Just get it out of there before July when the temperatures get up to 80+ degrees F!

Note also that I am not a Tribologist and I do not have an STLE certification so I am far from being an expert here. I would welcome *SUBSTANTIATED* feedback about anything posted here. Enter your facts in our forum (link is below) and if what you have to say is relevant, I'll update this page. However, you MUST state your sources if you take issue with any of the information I have posted.

UPDATE: On 3/3/11, Erik Buell (yes, THE Eric Buell) said of AMSOIL, "Fantastic technical performance, and a great company. We are using their lubricants exclusively in our new EBR motorcycle line".
- ED: While Erik is no longer with Harley Davidson, this is a very powerful statement! Although having said that, AMSOIL is not a silver bullet in all situations. There is a well known problem in Suzuki circles using AMSOIL 10W-40 synthetic motorcycle oil in Suzuki 1500 Intruder and Boulevard motorcycles. I've experienced this myself and have found Shell Rotella T-6 to be the best/least expensive (but certainly not the only trouble free) oil for this particular brand and model motorcycle. While AMSOIL is, overall, a very fine motorcycle oil, I would not recommend it's use in 1500cc Suzukis!


The Japanese Automotive Standards Organization (JASO) has created their own set of performance and quality standards for gasoline engines of Japanese origin.
For 4-stroke gasoline engines, the JASO T904 standard is used, and is particularly relevant to motorcycle engines. The JASO T904-MA and MA2 standards are designed to distinguish oils that are approved for wet clutch use, and the JASO T904-MB standard is not suitable for wet clutch use.

The American Petroleum Institute (API) sets minimum for performance standards for lubricants. The API service classes have two general classifications: S for "spark ignition" and C for "compression ignition" (typically diesel equipment). Engine oil which has been tested and meets the API standards may display the API Service Symbol (also known as the "Donut") with the service designation on containers sold to oil users.

The API oil classification structure has eliminated specific support for wet-clutch motorcycle applications in their descriptors, and API SJ and newer oils are referred to be specific to automobile and light truck use. Accordingly, motorcycle oils are subject to their own unique standards.

All the current gasoline categories have placed limitations on the phosphorus content for certain SAE viscosity grades (the xW-20, xW-30) due to the chemical poisoning that phosphorus has on catalytic converters. Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of Zinc dithiophosphate. Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue obsolescing oils needed for older engines. While [street] motorcycles are almost universally gasoline powered, C-rated (compression) diesel lubricants are typically recommended for motorcycle use. There are six diesel engine service designations which are current: CJ-4, CI-4, CH-4, CG-4, CF-2, and CF. It is possible for an oil to conform to both the gasoline and diesel standards. In fact, it is the norm for all diesel rated engine oils to carry the "corresponding" gasoline specification. For example, API CJ-4 will almost always list either SL or SM, API CI-4 with SL, API CH-4 with SJ, and so on. That is to say that you can usually put diesel rated motor oil in a gasoline powered car but not always the other way around.

The International Lubricant Standardization and Approval Committee (ILSAC) also has standards for motor oil. Introduced in 2004. For the most part, motorcycle manufacturers do not specify this standard in any products that we know of.

The ACEA (Association des Constructeurs Europe d'Automobiles) performance/quality classifications A3/A5 tests used in Europe are arguably more stringent than the API and ILSAC standards. CEC (The Co-ordinating European Council) is the development body for fuel and lubricant testing in Europe and beyond, setting the standards via their European Industry groups; ACEA, ATIEL, ATC and CONCAWE.

Because of the real or perceived need for motor oils with unique qualities, many modern European cars will demand a specific OEM-only oil standard. As a result, they may make no reference at all to API standards, nor SAE viscosity grades. They may also make no primary reference to the ACEA standards, with the exception of being able to use a "lesser" ACEA grade oil for "emergency top-up", though this usually has strict limits, often up to a maximum of litre of non-OEM oil. Harley Davidson may have at least partially hopped onto this bandwagon....

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