Good question, it makes sense that both would benefit. I think some diesel oils
do have friction modifiers, but not many of them. I've never had a problem with clutch slip, so I assume the ones I use (Castrol GTXD, Wallmart's finest, Halfrauds' own) don't have them, though that's hardly scientific. A web search would probably clear this one up. Phosphorus is higher in diesel oils, making them better at dealing with high pressure. Perhaps the modifiers used in petrol engined car oils have a negative effect on how the phosphorus works, or on the anti-shear qualities needed in a diesel engine, who knows?
Either way, plenty of people outside the UK use diesel oil. See
http://www.shell.com/home/PlainPage...nPageServlet?FC=/rotella-en/html/iwgen/ask_our_expert/app_askourexpert_faq.html
for one mention of using diesel oils in bikes. It makes sense when you think about it - so long as the modifiers aren't there, the formulation of a diesel oil is designed for high compression and should be good for bike engines, especially low-tuned ones like Honda's V-twins. Diesels lead a tough life, especially the modern stressed engines. Of course we have no need for anti-soot formulations, but they presumably do no harm. I doubt they are 'better' at protecting your pride and joy's internals than a high quality bike-specific oil, but I also doubt they are much worse, and certainly do the job.
The trouble with the modern biking community (mostly money-no-object 'leisure bikers', unlike poorer previous generations) is that we are quite vulnerable to marketing hype. Except for Enfields, bikes don't generally sell well when manufacturers tell us their latest model is low tech, or at least the same technically as a late '80's model. We want max power, lowest weight and high-tech materials and designs - the market is mostly about competition and racing, after all. Why
would anyone who buys into that use anything other than the 'best', most 'suitable' oil for the job? We don't see how these wizz oils perform, so it's a bit of an 'Emperor's new clothes' deal. All I want in an oil is something that protects my engine and doesn't cost a fortune. I don't care about whether I get a few more BHP because of its slippery properties - if I cared about power, I wouldn't have an AT
