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Bel-Ray Specialty Lubricants: Tech Notes, Vol 3, Issue 9

September, 2012

How to Read and Understand API and JASO Ratings

One question we receive a lot concerns how to compare different oils when making a purchase. Short of having access to a lab or an extensive knowledge about lubricants all you really have to go on is the packaging; those pretty labels that were designed to try to get you to buy the product. Fortunately most companies list the API and JASO ratings on the label. Once you understand these ratings the comparison becomes a lot less difficult.

API Ratings

API (American Petroleum Institute) ratings only concern the engine without regard for the wet clutch or transmission. The American Petroleum Institute has several different ratings depending on what type of engine the product should be used for (two-stroke or four-stroke, gasoline or diesel). Since the majority of motorcycle engines are four-stroke gasoline engines those are the ratings we will focus on.

All of the ratings for gasoline four-stroke engines start with an S (for Service); the second letter is the rating. Although considered obsolete by the American Petroleum Institute, SG is the minimum rating recommended by many of the motorcycle manufacturers and is still quite common in the powersports industry. The further down the alphabet the higher the rating, with SN being the highest rating currently available. To meet a given API rating several aspects of the oil are tested. The tests not only judge how well the oil protects the engine, but also how well the oil itself holds up. A few of the characteristics tested include wear resistance, oxidation and corrosion resistance, and deposit control. A product must pass every test to a satisfactory level to meet a given API rating. The four most commonly found ratings in the powersports industry are SG, SJ, SL and SM.

JASO Ratings

JASO (Japanese Automotive Standards Organization) ratings are used because the American Petroleum Institute does not

Look for the API / JASO ratings to
make knowledgeable comparisons.

set ratings for wet clutch compatibility. There are three JASO ratings we will look at. JASO MA is the minimum required rating by the motorcycle manufacturers for any motorcycle that shares its engine oil with the transmission and clutch. This rating indicates that the oil will allow enough friction between your clutch plates for proper operation. The highest available rating is the MA2 rating. A product with the MA2 rating will allow a higher amount of friction within the clutch. This means less wear over time, fewer harmful deposits in the oil, and potentially more horsepower and torque reaching the rear wheel. Oil that has the JASO MB rating, or does not have one of these ratings present, is not suitable for engines that share the oil with the clutch and transmission.


Most of Bel-Ray’s four-stroke powersports line meets or exceeds the API SM and JASO MA2 standards. The few products that don’t meet those standards were formulated to meet specific criteria within the applications those products were created for (Example: our Friction Modified Thumper Oil API SM / JASO MB was designed for dirt bike engines that have separate oils for the engine and transmission). Now that you have a better understanding of these ratings you can make a better comparison of Bel-Ray products to competitor products. Until next time, have fun and keep the rubber side down!

Bel-Ray 21st Century Motor Oil: The Best Lubricant of the Century

Over the years diesel engine oils have been categorized as commodity lubricants, when in reality they are not. Engine manufacturers (OEMs) require performance lubricants to meet the demands their engines are exposed to. Bel-Ray total performance lubricants, the very meaning of quality and excellence, are formulated diesel engine oils that meet and exceed OEM specifications. Bel-Ray products have proven their value in real world applications for many years.

Bel-Ray 21st Century Motor Oil, known now as Bel-Ray Heavy Duty Diesel Engine Oil, has a history of proven value going back many years. In 1987 the high performance of our products was shown in a field trial of a Cummins NT-855 engine—the Bel-Ray engine oil could extend the drain interval up to 500 hours! That is 100% more hours than the manufacturer’s suggested 250 hours. Bel-Ray 21st Century Motor Oil 20W-50 was tested against Shell Rotella 15W-40. When the normal 25,000 operating hours was reached and it was time to perform overhaul maintenance on the two engines, the engine that was lubricated with Shell Rotella needed a complete overhaul with an estimated cost around $40,000 USD. The cost of repairs for the engine lubricated with Bel-Ray 21st Century Motor Oil 20W-50 was only $430 USD! The total operating hours of the engine lubricated with Bel-Ray 21st Century Motor Oil 20W-50 reached 72,000 hours whereas the estimated maximum hours of operation was 60,000 hours.

This proven value case study caught the attention of maintenance engineers at some mine sites in Chile. Additional field tests were performed at Compañía Minera Cerro Colorado LTD, Finning Chile and Mina de Rosario Collahuasi, in the engines of CAT 3516B, CAT 793C and CAT 789B. The results obtained were an increase in drain intervals from 250 hours to 500 hours, 7% increase in the availability of the equipment, 50% reduction in lubricant consumption and less environmental impact due to the decrease in disposal of used lubricant. Currently the above mines are using the Bel-Ray Heavy Duty Diesel Engine Oil 15W-40 (61580).

Bel-Ray Heavy Duty Diesel Engine Oil, with one of the highest TBN levels in the market and the best additives to protect against wear and oxidation, is the best diesel engine oil that you can use to protect your engines.

By choosing Bel-Ray, you will have the confidence that your investment is our investment and we are here to protect your equipment. Bel-Ray Heavy Duty Diesel Engine oil is the very definition of quality and excellence.

What is a Normal Level for Wear Metal?

We are asked many times, what is the wear metal target for our equipment using your oil? This sounds like a reasonable question, until you take into account; the different sizes, loads, environments, contaminants and lubricants used in equipment. The question becomes much more complicated, but this is what we ask ourselves every time we review an oil analysis report. If we want our oil analysis program to help us determine machinery condition we need to ask, what is a normal level for wear metal for our equipment?

Many operations have multiple pieces of equipment that are of the same make and model or of similar configuration. By analyzing the oil analysis reports for your equipment you can get a much better idea of what is Normal and what the limits for Caution and Critical should be.

Start with an inventory of your equipment and the lubricants that are used. Subdivide the inventory into groups of like machines and lubricants. These pieces of equipment can be used as a family of machines that you can use to determine what the Normal wear metal level should be. Now review the oil analysis reports for each piece of equipment; you should have enough reports so you can see a trend for each machine. You don’t want to set limits on one oil report, you need trends to show what the real levels of wear metals are. Now, based on the determined levels for the various wear metals, you can calculate the Mean or Average and then calculate the Standard Deviation for the number of samples you have. You can use Excel to calculate these values for you.

The following is an example: The numbers represent 10 different machines and list the wear metal value of interest foreach machine. 102 is the Mean or Average of the 10 values. 44 is the Standard Deviation for the values. Now to determine the limits Caution and Critical for the group of equipment, we take the Mean or Average plus one Standard Deviation for Caution and the Mean plus two Standard Deviations for Critical.

Now you know what is Normal for your family of equipment and what the Caution limits and Critical limits are. This family of machine method is a much more accurate method for determining what is a Normal level of wear metal for your equipment. If you need any assistance with the process contact your Bel-Ray Sales Representative.