Lookie: http://www.projectmazda.com/host/redprotege/undervalvecover1.jpg http://www.projectmazda.com/host/redprotege/undervalvecover2.jpg It is a 1996 Mazda Protege with the 1.5 Z5-DE engine. It has 127k miles and seems to run fine, no valvetrain noise (has solid lifters) and seems to have enough power to get around. But I'm still concerned with the amount of sludge build up. Any suggestions on how to safely get rid of this stuff via flushs or cleaners? I don't know if doing a kerosene flush would be such a hot idea since the amount of loose crap it'd free up might clog oil passages. Any suggestions would be appreciated.