I would hope this is not a single point of failure. I would suspect you have an oil level, quality and pressure sensors and probably more. Any one of them could probably trigger a code if you have a critical problem. And other then you old iron heads out there who has a problem with their MB diesel loosing oil unless there is a crtical malfunction(oil cooler line busted). The dipstick tube is probably still there for the topsider. One might be able to get a dipstick and put in it if you are that crazy about it.

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My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory