Not sure what you mean.
Which oil dipstick? engine oil is the one at the front of the engine on the right side of the car, transmission is at the back of the engine, also on the right side of the car.
Aluminium tube - there is nothing like that connected to the starter, exactly where does it come from?
Where abouts is the rubber pipe in relation to the engine?
Could be heater, transmission oil cooling, power steering. On my E220 there is such a pipe under the crankshaft pulley but that's for the self levelling suspension and goes from the pump to the rear of the car, nowhere near the starter.
A photo would help.
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)