dip stick tube O ring

[mcung13]

I replaced it on 530i by slipping the o ring to dipstick tube first and then pushing the tube in. It required bit of force to pop it in.

Just on the very end of the tube? And is it just bolt further up the tube that secures it?

Not at the end of the tube, but at the ridge. Make it properly oily tough. You will feel it when it pops in place.
I spent some time trying different ways to get it in, but this way worked for me.
And yes, only one bolt secures the dipstick tube.