After reading a lot of great posts for pro and con Car vs. MC oil, I came across this article from Motorcycle Consumer News.

I want to emphasize I respect both sides of the fence, but I thought this article puts the question in context with modern car lube demands relative to motorcycles and the conclusions seem to be based on quantifiable facts.

It's your bike and your dime... check it out.



Motorcycle Consumer News

Motorcycle Oils vs. Automotive Oils

Surprising New Evidence on the Viscosity-Retention Question

Walk into any motorcycle dealership parts department and you are virtually guaranteed to see prominent displays of oils produced specifically for use in motorcycle engines. Since dealers are not about to waste valuable floor or counter space on a product unless it produces a decent profit, it is obvious that motorcycle-specific oils have become one of the premier parts department cash cows of the 1990s.

Of course advances in lubrication technology have resulted in some fairly expensive premium, synthetic and synthetic-blend products for automobiles also. But as you can see from our pricing research at a half-dozen auto parts and cycle parts stores, the average purchase price for the motorcycle-specific lubricants runs about 120 percent higher for petroleum products and 185 percent higher for synthetic products than do their automotive counterparts. (See Figure 1)

The companies marketing these high-priced motorcycle lubricants would have us believe that their products are so superior to the automotive oils as to justify paying two and three times the price. But are we really getting the added protection promised when we purchase these products? MCN decided to look beyond the advertising-hype, specifically to see if the claims of prolonged and superior viscosity retention could be verified. What we found may very well change your mind about what should go into your motorcycle's crankcase in the future.

So The Story Goes ...

Many motorcyclists have long doubted the need to pay the inflated prices asked for most motorcycle-specific engine oils. An even larger number of us have harbored at least some degree of skepticism about the claims made for motorcycle oils, but have been reluctant to turn away from them, for fear of damaging our precious machines if the claims should happen to be true. Most of this fear comes from very successful marketing campaigns mounted by the manufacturers and distributors of motorcycle-specific lubricants.

For example, a monthly trade publication for motorcycle dealers recently published an article suggesting, "negative selling techniques" to "educate customers" against purchasing automotive oil for their bikes. The example in the article begins with the benevolent dealer looking the poor, dumb customer in the eye and asking, in an incredulous voice, "You're not really using that in your motorcycle, are you?"

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.

The campaigns promoting motorcycle-specific oils have successfully indoctrinated an entire Generation of motorcycle riders and mechanics. The doctrine is now so ingrained in the industry that questioning its veracity instantly marks you as an ill-educated outsider. Even MCN has fallen victim to the hype, espousing the superiority of such products in these very pages. Our own technical experts from the American Motorcycle Institute have repeatedly advised our readers against the dangers of straying from the straight and narrow path.

What we, as well as the AMI, your local mechanic and all the other motorcycling publications

 

This appears to be the rather old article from MCN. Has good info in it, but is now outdated. Please provide the link to the source as posting this is a copyright violation, especially without attributing the source.

 

Here's the link: http://www.xs11.com/stories/mcnoil94.htm. Sorry for any potential indescretions, it was on the net and I figured public domain to share with a forum.

It is from the 90's, but seems to me even more relevant now as many car engines are smaller and higher revving with bike engines becoming larger displacement, sharing more common lubrication attributes than they did 10-15 years ago.

BTW Skip, I enjoy your posts!

 

Blueson2s,

Was there a chart or graph that went with this article?

 

This was the original oil test they published. MCN has since done a second test and had some followup articles. Basically they do conclude that a good quality automotive oil of the correct viscosity is probably OK to run in motorcycles, that the motorcycle designation is more for marketing and higher prices than real formulation. They do caution in later articles about some of the friction reducing chemicals in newer energy efficient rated oils, but these are only in viscosities that no one should run in a motorcycle, like 5w30 or 10w30. Most heavier viscosity diesel rated oils(C)do not contain these friction modifiers.

I run Castrol Syntec 10W40 auto oil in my Suzuki 1200 Bandit because that's the recommended viscosity and Mobil 1 20w50 vtwin in my Harley. Based on MCN's report, I'd probably do fine with 15w50Mobil car oil as well.

 

I recall this MCN article, which came out in the late-90's IIRC, but I disagree that it is outdated. Many of their assertions hold true today as they did when the article was written. The only caveat on friction modifiers has been that they should not be run in a wet-clutch environment (MCN Jan. 2003, p. 16). IOW, bikes that share engine and clutch oil might need to avoid these friction modifiers. I've read articles--one by Quick Throttle magazine, copied recently in this forum--that suggest that this claim is without credible evidence. I've run motor oils rich in moly in an HD Evo primary and never had a problem with the clutches. That said, I'm avoiding it in my new SG's primary for two reasons: (1) precautionary, and (2) primary oil does not need to be expensive or rich in additives, and any good fossil engine oil or ATF will do nicely. Redline even recommends their MTL, a gear oil, for the HD primary. I don't think it contains any moly or other friction modifiers, but their engine oil is rich in moly (>900ppm). This is good for the engine and almost everything else, but at best unnecessary for the primary.

In the Feb. 2003 issue of MCN they report that many of the car oils tested actually had higher levels of phosphorus and zinc than motorcycle oils, despite the often-held opinions that they contain less because of the threat to catalytic converters. Their observations of oil with friction modifiers was that it made transmissions shift smoother, but some complained about its effect on clutches. It isn't known if the oil was the real problem in these anecdotal reports.

MCN's later oil test, done several years ago (I quit subscribing in 2003), was marred by logistical problems, like losing several samples in the mail, which severely jeoporized the results of the test. Many modern oils contain moly, which is a friction modifier and IMO important anti-friction additive. Mobil 1 15w50, Redline, and Royal Purple are three leading oils that use it--and it is included in the additive packages of many "energy-saving" oils that you've already correctly said are too thin for motorcycle use. In the HD engine, friction modifiers are a virtue since their only alleged vice is possible averse reaction in wet clutches.

American Iron magazine also published oil tests, and they came to the same conclusion that "car oil" was perfectly suitable for MC's as long as the viscosity met manufacturer's specs. In fact, they highlighted one oil as a glowing example--Mobil 1 15w50, which performed as well as the VT variant and better thanmost other oils tested, and cost less than any other synthetic tested.

 

The only reason I called the article outdated was that the oils tested, and the results from those tests, are no longer valid. The oil formulationshave changed tremendously since the tests were run. Comparisons between the varied oils might not, and probably do not, applyany longer. As an example, the car oil Mobil 1 15w-50 has changed formulations at least 3 times since the article was written.

Pinned to the top of this forum are several articles about oil. Take the time to read them. Many of the questions that arise over and over again are covered in them.

 

Snobal,

There is a chart that goes with the article, but it didn't want to format after I copied it. If you have trouble with the link go to ask.com, type in car vs. motorcycle oil and the article can be found on the first page.

Iclick, agreed--old doesn't always mean outdated. Interesting to note the conclusions from later studies.

Editorial sidebar here. I've always used HD lube products until they eliminated their separate primary and tranny fluid. I was a fanatic to use only Bar & Shield stuff but when they made the change I started to question the application of an "all in one fluid." I totally agree with Skip that a "do-all" product has to make compromises across the spectrum of its application. I used it, but I didn't like it.

The fallout from this questioning got me reading posts here and researching on the net, challenging notions I've held for a long, long time. It's ironic that in some cases, some car oils may work even better than MC oils. For me good 'ol dino Castrol 20-50 GTX in the engine, Castrol 10-40 in the primary (I'm a Castrol fan, I restore vintage British sports cars as a hobby and have used it for many years with excellent results) and Mobil 1 75-90 in the tranny will be the combo of choice. I had a hard time deciding between F type ATF for the primary or Castrol, but with an open bearing and other components the trade-off seems better to assure good lubrication with Castrol and Clutch slip should not be a problem with dino juice.

My motivation to go separate product for engine, primary and tranny is not to save a few nickels (although it's a nice by-product) it's to provide the job it was specifically designed to do and to make a choice on what is quantifiable, not what some marketing language espouses AND, how cool to get what you need at any auto store or Walmart if you're on the road and ya gotta get the stuff.

I respect the different opinions and beliefs I've come across in researching this topic. There will never be a concensus on what is the truth behind Car vs. MC oil but as a gearhead, I'm always interested to keep learning and reading other opinions.

Gotta go, the Fatboy is getting thirsty!

 

My response to your use of "outdated" was to point out that the issue of car oil vs. MC oil was unchanged, not necessarily the placement of specific oils in the tests.

 

I started riding Harleys in the days when HD had no synthetic product to offer and there were old wives' tales floating around about skating bearings, etc. I used a synthetic oil in my '96 and it managed to survive without engine work for >100k miles on it. I also used a synthetic gear oil for the tranny, not HD's brand, which wasn't a full-synthetic.
The primary does not require high-tech oil, and for years I ran HD's Primary Oil, which I think was a good product, but when the price escalated >$2 I started using a $1/qt. oil from Walmart, and it worked just as well. Formula+ by all accounts is a 10w30 or 40 engine oil with no more than an average additive package, and at $6.50 (or thereabouts) is a ripoff. I'm using Castrol GTX, ~$2/qt. at Wal-Mart, and it also works fine.

I've used Castrol GTX 20w50 in my '66 Corvette (factory 427) for 24 years. I don't use anything "better" because it isn't driven much and doesn't need anything more expensive. Besides, it holds six quarts. For me, although I consider GTX perhaps the best of the fossil oils, I would use only synthetic in the engine and tranny. I did use GTX in my new SG during its break-in period, though.

To me, that's the beauty of having three separate holes, so you can select the right product for the right hole. I wouldn't want it any other way.