oil filter on a Mercedes 190E 1986 is in the back of engine
No they dont.
up top on left side... looks like power steering pump
castrol magnatex 10w 40 a3/b3
5 litres
Mercedes 2.6 (m103) oil pressure reliefThe oil pressure relief valve on a Mercedes 190e 2.6 (103) is mounted in the oil pump housing. Access is by removing the sump where the oil pump housing is located at the front of the engine. The relief valve consists of four components, a screw plug, a compression spring, a guide pin, and a piston. Remove the screw plug and withdraw the spring the pin and the piston. Refit in the reverse order to removal and torque the screw plug to 50Nm.
By this I assume you mean the amount of oil that will fill the engine to the maximum oil guage level when the engine is empty. For the 190E 2.6 it is between 6 and 7 lts (1.5gallons)
Picture of oil pump 32
The oil pump is located at the bottom of the engine, inside of the oil pan.
doesnt have one for that, only check engine, low oil, washer fluid, low coolant, break pads sensor, e-brake, high beam.
On top of engine at the back, on the right hand side, behind air filter.
Remove the air filter, And its located right in the back.