sounds like a decent car.

check the crank for warpage, check your rods for bends and twists
check the valve guides
get some new piston rings and main/rod bearings

check your cylinder bores for even wear

check your cam for any wear

let us know what you find!

__________________
Pierre Hedary 1985 280SEL, 1970 111.026 in progress
Mercedes technical advice hotline: 407 765 2867
[servicing older Mercedes in the state of Florida with competence and passion].

From the standpoint of an honest MB technician, Vegetable oil is a threat to your diesel engine's mechanical integrity.