When your car reaches operating temp, the oil pressure while idling, should float around the 1st mark on the oil pressure gage located on the cluster. Depending on the weigh of oil, the viscosity of the oil (15w50 vrs 0w 40/50) will influence the pressure. Pressure should always peg to to the top of the gage when depressing the peddle.

Do not over fill the oil capacity. Overfilling will have an adverse effect due to foaming. The oil level should be in the middle of the dipstick. Overfilling might be part of your current problem. I've never overfilled to 10quarts so I can't comment. Remove enough oil to bring the level to the middle of the indicator and see if your problem persists.

I don't think you will find a "paper" service manual for the W140. You can find a CD/DVD version. Others have had success using the Alldatadiy.com site.

I'm unsure of the cut off date for the M119 engines, when the oiler tubes moved to plastic. You might pose this question on the forum. You could always remove the valve cover and look, but this could create other problems depending on the age of your plug wires, upper wiring harness and old hardened rubber hoses on the top of the engine.

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML