A real important thing to realize when reading and giving opinions about oil and its worth on a forum like this.......
This is an American site so most information is based on American information and directed to an American populace.
Oil varies from country to country and continent to continent.
I have made the mistake before about basing information given about the XS650 from the gurus, (no disrespect intended or implied), based on American information and have applied it to mine here in Australia and found that some things are different. Some small things but could be very important to the overall running of the bike.
My point is on the oil, Learn about what Viscosity means and how it relates to your situation and combine that with research locally, from your local manufacturers, most will have the relevant information regarding ZDDP and viscosity flows information in their fact sheets.
One thing to remember is the standard for oil rating is a set standard. Some multiple weight oils may be a the top end of their rating, closer to a higher rating and some will be at the bottom end of their rating making a lower rated oil as good.
Higher ZDDP levels also affect the oil Viscosity and if ZDDP is added to oil it could do more harm than good, (Caution to angus67). Their is a myth that all oil companies removed or lowered their ZDDP content to .08 to all oils for environmental purposes, but the truth is the laws only applied to oils, (multiple weight), up to and including 30 weight oils. Some of the multiple weight 40's and higher still have more ZDDP than motorcycle specific oils.
Here is some information on ZDDP and its relation to oils and how the Viscosity flow rate is determined. I have included some technical data and the variations on weight aand ZDDP levels on one make of oil,
Modern Oils in Older Engines. From the Jaguar Driver Club
Understanding the SAE Motor Oil Viscosity Standard
ZINC MYTHS AND LEGENDS 2010 UPDATE Although this is from an oil company it explains the various countries requirements and a lot of the myths that relate to this discussion.
15W/40; semi synthetic car light duty diesel oil,
15W/40; heavy duty diesel oil,
20W/50; mineral oil for older cars
20W/50;motorcycle specific
It was some document from an oil company saying in effect reduced zinc was still a sufficient amount. Old engine, new engine, style of valvetrain; who knows. But I'm not seeing any problems. I get adjuster pitting but nothing else, so I'm still happy. No clear reason to switch to a much harder to find oil at the present time.
