Oh goodness, here is an old wive's tale (or maybe not!). I got deep into oil research a few years ago based on an oil thread. Yup, you know how that goes. Well I came across some interesting info and followed it to the source. I don't think I could find the link again but basically what it said was to add 1oz 2 stroke oil to 5 gallons of regular gas and use in your 4 stroke bike. Basically, that little bit of oil added better lubrication, protection to the top end, longer engine life. There was much testing done with best results at that mixture. I will see if I can find the article again and post it here.
What's your favorite? T4 or T6? I think old school thumpers like the klr like the T4. I found the old pigs just did not like the T6 synthetic as much.