I agree, best to pull them apart and do it properly, but, if it's the night before a ride and you just decided to change the fork oil rather than sleep and it came out mucky, then I have used kero, and I remove the top nut and pull the spring and put a dose of kero in and hand screw the top nut back on and "hand pump" the lower leg up and down, then drain and repeat untill all comes out clean. Dirsel would be probable be just as good. Works for me.