I run 10w40 or 15w40 oils, not picky on brand. I've been trying the common diesel oils. Using Delo in there right now. Delvac was on sale for $9 per gallon so I stocked up. I have diesel trucks too. I didn't know a oil could get rid of the first gear clunk. I can't tell any thing between a dino moto 10w40 and a dino 15w40 diesel oil as far as shifting goes. The 5w40 diesel oil shifts to hard for me, I only tried it once in both of my bikes. The FJR didn't like the stuff either.
I haven't had any issues with TwinAir filters and thats what I have in the DR with the PJ1 filter oil and cleaner. I use the standard NGK plugs. The magnetic oil drain plug seems to do its job well. After reading all the chain threads I'm still sticking to a 525 DID X ring and the 14/15 CS with the stock rear sprocket. I use Procycles CS retainer.
I do use a chain oiler, a simple TUTORO. So far so good, I like the manual operation. I don't run it all the time and drown the bike with oil. Just enough to oil the chain and no more. Turn it off well before hitting dirt etc.. Works for me. I used chain wax before and didn't like the build up and cleaning.
Upper chain roller was removed when the bike was new, still running the stock lower one, I should change it soon now that I'm riding the DR as my main bike...