R Klasse oil pressure light

I also drive an R Klasse. My oil pressure light came on some time ago. I checked the oil level first, and it was fine. Then I looked at the oil color. It appeared sludgy and darker than usual. Have you checked for oil sludge? Have you used any oil additives recently? An oil leak could also cause this, but you would see oil under the car.

Oil level is ok. I'll check for sludge and oil color tomorrow. No recent additives and no obvious oil leak. If it is sludge, what's the next step?

Sludge suggests infrequent oil changes. Exceeding the maintenance interval on these engines is a common issue. The contaminated oil loses its lubricating properties, triggering the warning. Without seeing the oil, I can't say for sure if that's the problem, but given your symptoms, I recommend taking it to a workshop to have it checked. An oil change may solve it, but it is important to rule out more serious problems.

Thanks. You were right. The maintenance interval was exceeded. The oil change with filter was 165€. The warning light is now off.