My daughters boyfriend has several Mazda RX7's. Two as parts cars, all three have bad radiators. You will see a few radiator issues on this site, but the only time I've ever had to replace a Benz radiator was due to damage. A coyote at over 55MPH will cause you to replace your radiator every time, so I don't know how far the original would have gone.
If you're keeping the cooling system flushed, I would expect you to have hose and other cooling system problems long before a radiator problem.
I replaced the hoses on my 300E two years ago. I'm wondering if the originals would have lasted longer. In spite of the catastrophic results of my split molded heater hose, I feel that I have done a good job of maintaining my cars. They're all coming down at once, but they are mostly things that periodic maintenance had nothing to do with, unless you want to say that I should have replaced the clutch as preventive maintenance. I don't think the vibration in my daughters car is the result of lack of maintenance.
I hesitate to post this on MShop. But Monday and yesterday I was driving another car I have, which is an American sports car from Bowling Green, Kentucky. The Vehicle Speed Sensor in the transmission went out which prevented the overdrive from working. This is certainly not something that preventive maintenance would have cured. Of course, that car is a love/hate relationship, I love driving it and hate working on it. I get way too many chances to work on it too. Had to drop the exhaust system, to get to the sensor, piece of %@#(.
The point of this rambling is not to discourage preventive maintenance. But even if you just replace everything all the time because it might fail, you're going to still have some failures, even on a Benz. In my case they just all broke at once.
I have replaced the clutch twice on my 240D, both times it had a broken pressure plate diaphragm finger intermittently jamming up the works and keeping the clutch from releasing. It was the only thing I had to drive this morning, the clutch behaved itself this morning. I got the new clutch yesterday and will replace it this weekend. The 240D is '70's technology, but it is RELIABLE. It has only broken down one time in a manner that caused it to be brought home on a rollback truck. It has a homing instinct. Somehow I know it will make it until I get everything else back on the road, which will probably be Thanksgiving or Christmas the way things are looking.
Thanks for your thoughts and for listening to my depressive ramblings,
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in