I know I have a slight oil leak from the head gasket ( maybe a couple of tiny drops a night) that I have lived with for the past several years. However, during the past couple of months, I noticed oil puddle on my garage floor has gotten bigger ( about the size of a bagel each night). Coincidentally, I have also noticed my oil consumption to have gone up to about a quart per 700 miles. I have cleaned my engine in an effort to determine where the leak might be coming from. After cleaning the engine and with the engine dry, with no trace of oil leak from the head gasket area, I still noticed that oil is seeping/leaking at the bottom of the engine where it meets the transmission housing. It appears to be engine oil and NOT transmission oil. I do not suspect leaky valve stem seals ( as the cause of oil consumption issue) as I have replaced the seals about 3-4 years ago. I would like to determine the source of the oil leak as my first step towards resolving the oil consumption issue. I am guessing, it could be upper oil pan gasket where it might be hidden by the transmission housing. any ideas where else I should look?

If you use a "catch" pan under the car?? see how much actually is leaking.
Sounds like a rear main seal leak.

Consumption sounds like valve guides.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Also may be your headgasket. Take a flashlight and see if oil is collecting under the intake manifold. If it is, it will drain to the back of the engine dripping at the torque converter like a rear main seal is bad.

thank you both for the inputs. The intake manifold theory is interesting. I will surely verify all possibilities.