I have a 98 e300 160K purchased with 15500 K, Having the head redone because of a seized glow plug due to carbon build up. I would recommend if any body is going to grease a 210 they should have the plugs changed and the head reamed and done every 25 to 50K miles this will prevent coking of the tips. Also much More frequent oil changes. I use Ams oil 15/40 and See 32+ mpg and changed it at 155000 mile from 0/40.I was going to goto 10K es on the ams-oil but the head is being worked on was first quoted 4500+ tax but with shopping around i got it down to 2500 out the door with all parts.

I you see your check engine light go on and the glow plug timer not going o you have a glow plug issue.