One more item for the checklist, bad gas.
My car recently suffered hard starting problems.
Fuel cleaner, and water remover did not help, new plugs didn't, cap, wires and rototr all ok.
refueld at one station and problem went away. refueld at another next time, problem happened again. Refueld the last 8 times at same station, problem has not happened since.
Low octane in the hi test pumps to make more profit is what I have experienced first hand at a few stations here. It will cause similar symptoms to what will cause rough idle and wierd probs.
As for chains, MB chains are known to be quite reliable. Most last 100k if not more.
What larry says is great advice. He has put hundreds of thousands of miles on his cars, before any major work was done. Changing the oil hot and often is preventative maintnance at its cheapest and easiest.
It costs me maybe $25 every 3000 miles for oil changes. The car will be better off as long as the oil is clean and the filter is new.
I agree that damage occurs on startup, thats a given, but mb engines were designed to pressurize in seconds to reduce the wear.
My brothers car has 160k on the odo. Its a 1985 380SL with the double row timing chain. Our mechanic recommended doing the chain as preventative maintenance sometime in the next 10k miles. We have no idea if it was ever done before, but the car still drives great. The mech would charge only $500 or so to do the chain, which I think is very cheap. I told my brother he might as well do it now, but he's the kind of person that likes to break cars and abuse them.. He's the only person I know, who has had to get rid of every car he had because of catastrophic failure.
All my cars were still running very nicely when I got rid of them.
Maintenance works, preventative maintenenace works. Find a good mechanic, or buy the manuals and cdroms and do it your self, either way you can't go wrong.
Every thing you do to be preventative helps.
Alon