Well, I got through my ex'es mom's brake job and now she tells me she's burning 1 qt. of oil every 500-600 miles and smoking a lot. It's an '88 560sl with 79,500 miles. She says there are no drips or puddles under the car, so I assume this is major engine damage here. I'm having her take it in for a compression check and some other diagnostics. But can anyone here tell me about the normal life expectancy of this engine and what a rebuild costs? I told her it was probably a huge and expensive job and she still said she wanted to keep the car at all costs. So what could she be looking at here? Thanks.