Unfortunately, fork oil doesn't really have a standard. Bell ray's 6.5 maybe Gloden Spector's 8.0 You want quick and simple? Go down to the BMW shop and get what's recommended for your bike. Or, you take my word, a guy you never met, and use Mobile 1 synthetic ATF. That's what I use. I like it. And I'm known as an upstanding pillar of society.