Motorcycle Motor Oil

by Mike Guillory


This article was written by Mike Guillory and he has curmudgeonedly allowed me to post it here. I think it offers an excellent perspective and discussion on oil! It certainly has helped to shape my opinion on this complex subject. And to frequent visitors, this article was updated in June 2002.

Brief Introduction

Along with keeping things adjusted properly, using a good quality motor oil and changing it regularly is the key ingredient to keeping your motorcycle running happily for a long time. You cannot go wrong using one of the various "motorcycle-specific" oils, now available also from some of the major oil companies. However, many motorcyclists object to the higher prices of those oils and for convenience prefer to buy oil at their local automotive supply store, which is a still a good option. This article will provide you with information to make an informed choice.

Price of Motor Oil

So how do you make an intelligent choice? Will $1.00 a quart automotive oil work okay or do you need to pay $4 to $12 a quart for "motorcycle" oil? You have to answer that question yourself, but here are a few facts to help you make the best decision for your situation.

The owner's manual of your motorcycle probably says something very similar to the following:

Use only high detergent, premium quality motor oil certified to meet API Service Classification SF or SG (shown on container). The use of additives is unnecessary and will only increase operating expenses. Do not use oils with graphite or molybdenum additives as they may adversely affect clutch operation." That's pretty clear. But what do you do since automotive oils now say on the container "meets SL Service?" That's easy! By consensus of the API and the manufacturers, the current SL classification meet all requirements of SF, SG, SH, and SJ plus all earlier API gasoline categories. The current SL actually offers some additional benefits over the older classifications. So, if the motorcycle requirement says "SG", be confident that "SL" indeed meets that requirement.

The Vanishing Zinc and Phosphorous

It is a fact than many SL oils now contain lower levels of ZDDP (the zinc/phosphorous extreme pressure additive) and that is a big concern to a lot of motorcyclists. ZDDP is a last resort protection against metal-to-metal contact. Whereas a few years ago the zinc level was typically 0.12% to 0.15% in SG automobile oils, some SL oils now have as little as 0.05%. However, this in itself may not be a problem since normal operation of a motorcycle on the street would never result in metal-to-metal contact any more than it would in your automobile. Remember these SL oils meet the most demanding protection requirements of modern, high-reving, powerful 4-stroke automobile engines (among others). And there is no reason to believe the lubrication requirements of street motorcycles is measurably different.

However, if you race you probably need higher levels of ZDDP and should use appropriate oils or ZDDP additives.

NEW Motorcycle Oils

Seeing an opportunity to bridge this perceived gap between motorcycle oils and automotive oils, many traditional oil marketers like Castrol, Mobil, Pennzoil, Quaker State, and Valvoline now sell their own "motorcycle" oils at very competitive prices, and alongside their automotive oils. I have found them at several of my local autoparts stores and even at one WalMart store. Call or visit the auto supply stores in your area and ask. Even if they don't routinely stock them, they probably can order a case for you at substantial savings because their mark-up is generally quite a bit less than motorcycle shops.

Although not a motorcycle oil, oils with the designation "Racing Oil" are not intended for street use, generally meets "SG" requirements and has somewhat higher levels of additives, like ZDDP. An example is Valvoline's VR1 Racing oil available in 20w50 weight. These should work fine in our motorcycles.

Energy-Conserving Oils

Some are concerned that the new "energy-conserving" motor oils may have "friction modifiers" which will cause clutch slippage. Since that is a legitimate concern it is best to use only oils which are NOT "energy-conserving for motorcycles with wet clutches." Read the back of the container. It clearly identifies this. In general, only the very lighter oils, like 10w30, 10w20, 5w20, are energy-conserving. All 5w40, 5w50, 10w40, 15w40, 15w50, and 20w50 oils which I have found are not energy-conserving and can be recommended for general motorcycle use.

It is commonly mis-stated that "SJ and SL oils have friction modifiers which will cause wet clutch slippage." In reality, all oils have friction modifiers, that's how they work. ZDDP itself is a friction modifier. The real issue is to avoid getting the friction so low, with very thin oils containing extra amounts of friction modifiers, that clutches will slip under normal use. Stay away from energy conserving oils and you should be fine, if your clutch is in good working order.

Synthetic or Conventional

What about synthetic vs. semi-synthetic vs. "dino" oils? All motor oils have several special additives formulated into the oil to protect from corrosion and wear, plus detergents to keep combustion products in the oil. For normal (non-extreme) use, "dino" oils protect as well as the synthetic oils. However, if you plan to race, run at extremely high temperatures, or plan to extend oil-change intervals, or simply want the best, then a synthetic or semi-synthetic may be your best choice.

Real World Test Results

Are there any "real world" examples of long motorcycle engine life using automotive oils? There is a good one in the June 1996 issue of Sport Rider magazine in a report called the "100,000 mile Honda CBR900RR." The owner used conventional Castrol GTX oil, 10W40 in the winter, 20W50 in the summer. He changed it every 4,000 miles, changing the filter every OTHER oil change. No valve clearance adjustments were required after the initial one at 16,000 miles. And a dyno test against the same model with only 6,722 miles showed torque and horsepower virtually identical. The 100,000 mile bike was even used for some racing. In a subsequent follow-up, the same CBR had passed 200,000 miles and was still going strong! Plus, many motorcyclists have emailed me with their very positive results using nothing but automotive oils for years in a variety of rides. Oils have changed over the past 10 years, but that just means we need to be more careful in our choices.

Frequency Asked Questions

  1. What is a reasonable oil-change interval?

    Most manuals recommend not to exceed 8,000 miles after break-in. But short-trip riding is considered severe service and the most common oil change interval is 3,000 to 4,000 miles. However, a long trip is the easiest service for the oil and going 6,000 to 8,000 miles between changes while on a cross-country ride is routine. Also, the use of synthetic oils can easily double the oil-change interval.

  2. Will changing the oil even more frequently, like every 1,000 miles, prolong the life of the engine?

    Not very likely, because even at 3,000 to 4,000 miles, the oil and additives are not degraded very much. Changing more often just wastes money.

  3. What about the claims that motorcycle-specific oils contain "special polymers which are resistant to breakdown caused by motorcycle transmissions?

    Oils usually require the addition of polymers, called VI improvers, to create a multi-viscosity oil, like 10W-40. Whether it is a motorcycle oil or an automotive oil, all polymers are subject to some degradation in the transmission. Full synthetic oils tend to have less polymer than conventional oils and therefore degrade less.

  4. Why are motorcycle oils so much more expensive than automotive oils?

    Cost of doing business is higher per quart of motorcycle oil. Large oil companies make so much more product that their profit margin per quart does not have to be so high. That's why the newer motorcycle oils being marketed by some oil companies are only marginally more expensive than their automotive counterparts.

  5. What about the claims by specialty motorcycle oil manufacturers, that their oil is better?

    That's a good one. Next time you hear that line, simply ask, "What evidence do you have?" I've never seen any. If you do get any, please let me know! I don't believe that there is any.
Now, armed with all this information, you are ready to make your choice between automotive oil and motorcycle oil. Either will work fine. Your motorcycle probably cannot tell any difference. There are many riders, the author included, who use nothing but good quality automotive motor oils. There also are many who use nothing but motorcycle oils. All indications are that both choices work equally well because motorcycle engines are designed so well that the oil really doesn't make any measurable difference. As long as it meets SG, SH, SJ, or SL service requirements.

In the past several years, various reports went around regarding independent studies that showed "automotive" oils that are not energy-conserving (EC) work just as well as motorcycle-specific oil and in many cases better. In former revisions to this article I listed the oils I found locally (Houston, Tx) that were 10w40 and heavier and not energy-conserving. I've discontinued that as it adds little value. All one needs to do is look at the back of the oil container where the lower half of the identification circle will have the words "energy conserving" if it is. Don't use those in wet clutch motorcycle applications, as they may cause clutch slippage. If the lower half of that circle is blank, as all 10w40 and heavier oils should, that means it is NOT energy conserving and should be fine in wet clutch applications.

Heavy-Duty Oils

My favorite oils and the ones I most mostly recommend for motorcycle use, are the "heavy-duty" oils. They are commonly misunderstood, and often referred to as "diesel oils." They are NOT energy conserving, have higher zinc levels, as high as 0.16%, and by virtue of their multi-duty have a better engine protection package than an oil that is only rated "SL". These heavy-duty oils are rated SJ or SL, plus CH-4. They are currently closer in formulation to the motorcycle specific oils and to the "SG" oils that many motorcycle makers recommend. Following are some examples of these oils, generally 15w40 oils by industry convention. There may be several other 15w40 oils that I am not familiar with.

  1. Castrol RX Super 15w40
  2. Chevron Delo 400 15w40
  3. Mobil Delvac 1300 Super 15w40
  4. Pennzoil Long-Life 15w40
  5. Quaker State 4X4 Synthetic Blend 15w40
  6. Shell Rotella-T 15w40 (my personal favorite)
  7. SuperTech 2000 (WalMart) 15w40
  8. Valvoline All Fleet 15w40
  9. Castrol Syntec Blend Truck and 4X4 15w40
Full Synthetics - for Maximum Protection

For years Mobil One 15w50 has been a favorite of motorcyclists. In recent years it has gone from its original formulation to an improved SJ "TriSynthetic", and more recently as SL "SuperSyn." several of us have received conflicting information on this new "flavor" of Mobil One, but the consensus appears to be that the new SuperSyn has additional friction modifiers and may no longer be a good choice for motorcycles. However, I have heard from several VFR owners still using it with favorable results. Therefore, YMMV. Mobil naturally recommends their motorcycle Mobil One.

A fairly new player in the synthetic market is Shell with Rotella-T Full Synthetic 5w40. It is not energy-conserving and according to Shell performs competitively with Mobil Delvac One full synthtetic, which means it offers even more protection than does Mobil One 15w50. A number of motorcyclists have reported to me good results so far with his use of the new Synthetic Rotella-T. I put it in my own VFR at my last oil change.

Delvac One should be an excellent motorcycle oil but is generally available only at truck stops or in commercial quantities. For those who may have connections with a long-haul trucking operation, where Delvac One is known to be used in oil change intervals up to 150,000 miles, or even more, you may want to try it if the price is right.

There are a number of other synthetic and semi-synthetic oils available and I have no reason to believe they are in any way inferior. Just follow the advice and use one which is not energy conserving.

Important Note: Be sure and use the recommended viscosity range, e.g. 10w40, 20w50, etc. for the climate in your area. In general, to protect your motor use the heaviest oil you can that still meets the manufacturer's guidelines. For example, 20w50 is better in warm weather than 10w40, because it gives you a thicker oil cushion between bearing surfaces at operating temperature. For racing, a thinner oil will offer less resistance and thus more power, but will offer less protection.

I personally believe in these oils and use nothing else in my motorcycles. As always, you have to make your own, informed decisions.

A Note on Warranties

Since it is generally accepted within the industry that current classifications also meet all older ones, there can legally be no warranty issue. In fact, some oils actually say on the package "SG" in addition to SH , SJ and SL. However, if any of the very newest motorcycles specify oil meeting the new JASO, or other motorcycle-specific oil specifications, and no reference to "SG" or similar automotive specs, then you may have a potential warranty issue so behave accordingly.

And finally, it is gratifying to have received so many emails the past three (3) years from motorcyclists finding this oil and oil filter information useful to them. Keep them coming. I am happy to help, and I plan further updates as things change significantly. Please refer to Oil Filter Alternatives - Honda Motorcycles also by Mike Guillory for a comprehensive review of various oil filters.

Web Master's Note

The author is a Chemist, retired from a major Oil and Chemical Company, after a career in the Quality Assurance of Fuels, Lubricants, and Chemical products. He and his wife both ride.

Mike in Houston
'94 VFR750 "XENA"
'85 V65 Magna "YELLOW SONIA"

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