Ok, I'll just give you my preferences. I don't want to get into 5 more post having to defend my personal choices.
Motul, Motul, and more Motul. I love the stuff. I no longer have the article, but I remember about 2 years a technical, un-biased report came out specific to motorcycle oils. When an internal combustion engine fires, it burns gasoline which has a high concentration of sulfur, it uses atmosphere to get it's oxygen (only 21% of air is oxygen), and it ingest large doses of moisture which condenses inside the engine internals and exhaust where they will remain unless burned off. The resultant mixture is sulfuric acid. Motul was one of the leaders in additive packages that combatted the effects of sulfuric acid by having propietary additives that helped to neutralize the acids that form.
Any and all short rides generate this sulfuric acid becuase the cool engine and low exhaust heat during warm-up generate a lot of condensation with blows by the rings and makes it's way into the oil. It's not an issue on a 2 stroke because each intake charge brings a fresh supply of oil and fuel - every bit a total-loss system. The transmission is also seperate and never gets exposed to the combustion process, so you guesssed it - no sulfur, no condensation = no acid.
The CB's and the XS's and the VF's you mention try to have their cranks, clutch, transmission, and rings all live in that same cozy place -the crankcase.The thing I can never convince many people to try is to spend the $10 or so to put 1 change of synthetic oil in your air-cooled and abused lawnmower for 1 season. The color and quality at the end of the season will have you preaching too. I swear, every lawnmower I have owned in the last 20 years gets a first oil change to Mobil 1. Go out this wekend and crank your $200 Briggs and Stratton, let her warm and drain. You'll likely smell it, it's burnt, it's black, it's way too thick. But, let it drain. Now put in he 1-2 quarts of Mobil 1 10-30 synthetic and run it for the rest of this year. Heck, mine has been in my 9hp Snapper for 2-3 years now and it's almost as clean as the day it was changed - this mower with bagger is used once, sometimes twice a week. In fact, I don't worry about oftern changes because the mower runs long and hard enough to get hot and the moisture is boiled out from any condensation that might have occured. Do that $10 test, then come back and argue. You'll put it in everything you own. The key to remember is that the combustion chamber walls get up to 1,400 degrees. Conventional oil splashing up on the cylinder walls and under the piston burns and smokes at just over 300 degrees. When the oi burns, it not only causes varnish and vapor, it leaves a thicker oil in the pan for the next start-up where the oil pump is going to try and pump it's life-giving juice to vital parts. Combine that with impeded flow, you've got metal-to-metal for the first several seconds of every start-up. Motul, Redline all have a flash-point in the 500 degrees range, they have buffers to help reduce the effects of acid, they flow when cold much better -yes, I have my opinions and preferences.
One last kick in the pants - save the next 6 pill bottles or take a small, clear assortment tray (hardware store variety) and put just a little oil from your favorites in the bottles or compartments. Now take at least one of the synthetics of the same weight and pour into one of the bottles or compartments - the key is to have them all the same shape, quantity, and size - Now, freeze those samples in your freezer overnight. The next day, carefully move the tray or the bottles and see for yourself how slowly/thick the conventionals react when compared to a good synthetic - you'll say to yourself "man I want this synthetic in my oil pump so it gets where it's supposed to be about twice as fast as the conventionals, plus at start-up, I need to be careful and not flog it until oil pressure and a little temp is there to help flow.
Preaching Sunday over. Sorry, you but you did ask
Gordon
