82 300SD Oil in turbo charger

It won't start because:

1. it doesn't crank?
2. it cranks but won't fire?
3. have you checked the glow plug relay's fuse?

Oil inside the air cleaner is common and can be fixed so don't let that mislead you as to the current no start problem.

These engines don't just die, they exhibit lots of symptoms before their death so take another look at it.

Glow plug relay is a black box on the left fender. It has a plastic cover that unlatches and slides UP. Under that cover is an 80 amp fuse or fusible link; it should be intact, your car's is probably not and needs to be replaced. Dealer sells these for $1 or $2, buy a spare.