How to clean gunk off piston head?

[ImpactX]

Took my compressor high side off to put in new o rings. It was cover in black gunk. I try scrubbing it with a wet towel. I got most off but there are some that just won't come off. What can I use to clean it? Can I use something like break cleaner or wd40? 

 

[biohazardman]

 

Thant gunk is from the type of oil you use. You should probly change to the correct oil.

Yes you can use those, to clean it off, but be sure you don't get it down inside of the cylinder or on the o-rings or damage can occur.

 

[heavy-impact]

Carb or brake cleaner.

 

[cwcarrera]

A Scotchbrite pad with some mineral spirits will be helpful.