Gummed up tubeless valves

Is there any trick to unclogging gooed up tubeless valve cores? Petrol, white spirit, WD-40?

This is not a wind up.
any degreaser will do..Acetone is the king if you have it..its in Nail Varnish remover..
Petrol is never a good degreaser theres oil in it. but even wd40 will do the trick !!
Slightly mixed up there Rich,petrol is a perfect degreaser.Its diesel that is oily,and so not a great degreaser.
i don't know Mick..I was told by a scientist that petrol is nearly as oily as Diesel and leaves a residue but as we were involved in something other than cleaning bicycle bits, go on then !