Yes, I would agree with you in principle as the service CD is totally useless when it comes to the bit with the compression test, I did mine a few days ago on the 500SEL (117 engine) and just used some sound engineering practice. I remember changing the plugs some 10000 kms ago and then use anti seize compound and cranked them up to the book figure of 25Nms. When I tried to gem them out this time, oh boy, were they tight, and all gummed up too ? I will never again use antiseize grease on an alloy head. I thought that the dissimilar metals might give me problems when it came to changing them, and it just made it worse ! The 117 engine plugs a re a bit tricky to get at quiclky as I had to use a different combinations of 3/8" drive extensions and universals. By the time I had finished, the engine was fairly cool and this time I replaced the plugs nice and clean and wrenched them up to the higher end of the torque setting. I guess this debate could go on forever, just depends on your choice and experience. I do agree though that you need the engine as near as you can to it's normal operating temperature. ( just as you do when you change the oil, eh Larry ?