I recently ran out of the chain lube I was using (Yamalube -- dealer recommended). It was always kind of tacky (even after drying for a few days) and picked up a lot of dirt, so instead of just buying the same stuff again I thought I'd do some research and see if there is something that might work better. I read a lot of chain lube threads here and needless to say, there are a lot of different opinions as to what is "best". There is some consensus that cleaning with WD-40 is a good idea. Some people use WD-40 exclusively. Others say WD-40 is bad for the O-rings and/or can get past the rings and dilute the factory lube. Being naturally curious, I went to RK-Japan, the mfr of the OE chain on my DR-Z400: http://global.rk-japan.co.jp/ There I found the US distributor: https://rkexcelamerica.com/products/rk-chains/ On their website I found this PDF: http://rkexcelamerica.com/wp-content/uploads/2018/04/1461079033a68e02b1b46743bafb1f09a74a0687b3.pdf In that PDF, in BOLD red font it says: "DO NOT USE KEROSENE OR WD-40 on a sealed chain!!" So I called the number listed: 760-732-3161. The guy who answered said they (RK Excel America) are 'middlemen'. They simply repeat what RK Japan tells them. He did say that WD-40 used to be OK, but is no longer recommended. He did not have any answers, so he connected me with marketing. The woman I spoke with confirmed that WD-40 is no longer recommended, because it disintegrates the 'nitrile butadiene' O-rings. Specifically, she said it "changes the molecular structure of the O-rings". She stressed that any cleaner or lube must be labeled "O-ring safe". Being a cynic by nature, it occurred to me that perhaps RK has their own products and saw WD-40 as the competition, but she said they sell nothing here in the U.S., only in Japan. So no conflict of interest. It looks like nitrile butadiene is not the most chemical-resistant material: https://mykin.com/rubber-chemical-resistance-chart I've ordered a can of Bel-Ray Super Clean lube to try, but I'm looking for an O-ring safe chain cleaner. According to the chart at the link above, denatured alcohol and methanol are fine, but there's probably something better. Oddly, it says kerosene is OK as well. Essentially all oils that I saw listed are safe. Stoddard Solvent is listed as being O-ring friendly. Near as I can tell, it is mineral spirits. Unless there is some reason not to use it I may go that way. In any case, I figured I'd pass that on FWIW.