used motor oil for fuel

[furyfins]

I am new to this site. I had been running between 50 and 90% filtered to less than 10 microns used oil picked up from auto shops and ran through my 3 stage filtration system. Have ran a truck a 7.3 mechanical injected ford turbo diesel with nearly 200,000 miles on this for approx. 20,000 miles with minimal trouble. Recently have been putting about 10% of this filtered oil in my girlfriends 97 tdi jetta. Have seen no change in how it runs. Has anyone experimented with used oil in TDI's? I am thinking about uping the % as the weather gets warmer.

[chittychittybangbang]

You could but as you have hinted at, the wear inside used motor oil isn't good for the long term life of the engine. I don't know how fine it can be filtered. On your 97 it's certainly more tolerant than a 2004+ PD engine or new common rail engine, not just in the fuel injection but the emissions filters.

You mentioned "minimal trouble" Would that be worth it with the girlfriend if her car has a problem