really? **** damn nanny governments mek is the good **** for this job(it is/was used as the main component in parts washer solvent for DECADES but i guess my grandfather dieing at 87 after spending 60 years as a mechanic just isn't long enough of a life span so they bans it, totally unrelated heart failure by the way), next best is lacquer thinner, if that's illegal too then settle for the lacquer film producing gasoline and yes gasoline will leave a lacquer in the cooler it probably wont hurt anything but its not the best(if you spill gas on your clothes they will still reek of gas even after all of it evaporates, that's lacquer), and good luck trying to flush it with anything thicker than gas, tranny fluid and gear oil will get it dirtier than when you started.
oh and acetone that will work awesome unless that's banned too
Edit: Making MEK illegal is so frikken over kill the epa even says it is very unlikely to cause real harm
http://www.epa.gov/chemfact/f_mek.txt it also is nolonger an HAP they delisted it in 2005, it was only on the list in the first place because they didn't really know if it was or not.