I'm aware of how to check the oil level on the W210 via the instrument panel, as I had a 99 E300 turbodiesel from 99 until 02.

With the key in pos 2 (but engine not running), the normal msg talking about how the car must be level yada yada displays ... then says checking the oil level is not possible.

I'm leaning toward a gunked up level sensor given how dirty and contaminated the oil is in that car.

Lance, if the condition of the oil is that bad an immediate oil change is warranted. Be sure to remove/replace the oil level sender after the oil is drained. You may want to research some additives that could be used briefly to "clean" the engine internals before changing the oil.

At idle does that engine make any strange noises, such as very noisy hydraulic valve lifters? It's a shame the owner has abused that vehicle.

Engine oil flush can cause engine damage and isn't recommended. Sludge builds up slowly and if suddenly broken loose by a chemical, the oil pickup screen can become clogged starving the engine for oil pressure.

For the most part, sludge will just sit there in low areas and not cause an issue. If oil galleys are becoming clogged, the only safe method is disassembly and removal by mechanical means.

Our guys solution would be to change the oil now, run the car to hot then park it, remove the oil cap and let moisture escape. Repeat this cycle a few times then change the oil at 2,000 to 3,000 miles. After this is accomplished, revert to oil changes every 4,000.

I think we need to get back to the first post. The request was to check the oil. The mayonnaise doesn’t mean the end of the world. Change the oil anyway and send him on his way. The less done to the car the better. Otherwise when the next thing fails our friend Lance’s good intentions will be on the hook. The car is being driven into the ground and the owner is going to change habits. Putting effort into the car now won’t change that.

Gift the guy a dipstick from a 98-99 E320 so he doesn’t come back.

Sixto
98 E320s sedan and wagon
02 C320 wagon

I did exactly that...changed the oil and filter, then sent him on his way with a dipstick.

Thanks for the replies!

Quick Update -

He's driven about 700 miles (mostly highway) and so far, the oil cap and valve cover opening remain clean and free of that nasty slimy crap. Keeping our fingers crossed.