pouring grey smoke out of an 07
 

hey everybody looking for some confirmation. i am working on a 2007 f350 6.0 with no mods. he said it just started running bad all of a sudden and pouring grey smoke. only codes are cylinder number 8 contribution/balance. ran cylinder contribution test and all seven cylinders except number one are showing negative readings at idle. i have done other egr problems before and all of them had white smoke pouring out but this is more grey. i am wondering if i have a stuck open number eight injector mixed with a cracked egr cooler causing the grey instead of white smoke. has anyone seen grey smoke from a cooler. it is also low on antifreeze and has a mild extended crank. thanks for any advice.