ok this is from 94 but still
a few highlights
Help From the Scientific Quarter
About the same time we began looking into the oil viscosity retention question, we received a letter from John Woolum. a professor of physics at California State University - and a motorcyclist - who noted that he was investigating in the same area on his own. Not being ones to look a gift horse in the mouth, we contacted Dr. Woolum and encouraged him to expand his research on our behalf.
Later in this article Dr. Woolum explains the laboratory procedures he used to generate the statistics used in this article. but for the mean-time let's just take a look at the bottom line when five popular oils (three automotive and two motorcycle) were compared for relative viscosity retention after use in the same motorcycle. (See Figure 2)
As can be seen from the figures, the best-performing oil of the group tested was Mobil 1 automotive oil, a fully synthetic product. In today's market, virtually all oils sold are to some extent para-synthetic, since even standard petroleum products usually contain at least some synthetic-derived additives. However, for the sake of simplicity in this article we have listed the products as petroleum if the primary components are from basic petroleum stock. Those listed as synthetics have their primary components derived from basic synthetic stocks, and may or may not contain any additives derived from petroleum products.
The results of these tests seem to support some of the long-standing theories about oils while casting serious doubt on others. Going by these tests it would seem logical to assume that:
1.The viscosity of synthetic-based oils generally drops more slowly than that of petroleum-based oils in the same application.
2.Comparing these figures to viscosity retention for the same oils when used in an automobile (see later text by Prof. Woolum) would indicate that motorcycles are indeed harder on oils than cars.
3.The fastest and most significant drop in the viscosity of petroleum-based oils used in motorcycles occurs during the first 800 miles (or less) of use.
All of these results (1-3) agree with everything the oil companies have been telling us all along. However, the same test data also indicates that:
4.The viscosity of petroleum-based oils, whether designed for auto or motorcycle application, drop at approximately the same rate when used in a motorcycle.
5.There is no evidence that motorcycle-specific oils out-perform their automotive counterparts in viscosity retention when used in a motorcycle.
These last two results (4-5) definitely do not agree with what the motorcycle oil producers have been telling us. In fact the test results not only indicate the two motorcycle oils being outperformed in viscosity retention by the two automotive synthetic products. but even by the relatively inexpensive Castrol GTX, which is a petroleum product. This directly contradicts the advertising claims made by the motorcycle oil producers.
What we, as well as the AMI, your local mechanic and all the other motorcycling publications have been doing is simply repeating what we have been carefully taught to believe over the years. The only problem with this approach is that our only source of information has been the people who stand to profit from our faith in the superiority of motorcycle-specific oils.
The idea, of course, is not so much to educate as to frighten the customer into paying for the more expensive motorcycle oil that only guess-who sells. Such techniques have played on our fears with great effect, to the point where high-priced, motorcycle-specific lubricants have become staple profit producing items in the majority of motorcycle dealership parts departments throughout the country.
In most cases where motorcycle oil producers show comparisons between their products and automotive oils, you will find them using SE- or SF-rated oils as the "automotive standard." These are oils that were designed and rated for the cars of 10 to 20 years ago. We have yet to see a motorcycle oil compared in testing to the 1990's standard, SG-rated premium automotive oils.