Sorry I also knew you were on regular diesel currently.I was just trying to correct the waste motor oil versus wvo issue.

I still think now that if you have never checked the injection pump timing since aquiring the car. Previous owner or owners may have retarded the timing to cover up the number four cylinder issue would not suprise me. If so should be an easy fix. Hopefully that will be all of it.

.I also do not think either that putting only seventy gallons of used motor oil through has particualrily had any negative effects. Other than perhaps some carbon buildup.