Yellow gunk in brake reservoir?

[Katman]

....and are more hydroscopic.

As odd as it might sound, the word is actually hygroscopic.

[AllanB]

Other possibility, it already had 5 in it and his mate put 5.1 in?
Do any of us really know what the last mechanic put in the bike unless we bought it in the crate and installed the fluids ourselves?

Awwww man now you are really fucking with Casssssss's head! But a fair point.

[nodrog:Me]

As odd as it might sound, the word is actually hygroscopic.

its grease lightening.....

[schrodingers cat]

As odd as it might sound, the word is actually hygroscopic.

Hmmm struggled there didn't I?
Mind you, I can spell pedant.