I don't believe it but apparently it works 9 times out of 10.
Experiencing a slipping box and losing drive after a few minutes? Happened to me once, mechanic told me it needed a new box so ended up scrapping the car. Wish I had been told this little trick beforehand. For the cost of doing it over replacing the box or the whole car, it's worth a try I reckon.
Drain the box, fill to operating levels with diesel, yes diesel, run the car for about an hour (in gear on some axle stands I guess), drain and clean filter and refill with proper fluid. Fixed!! Full function restored!!
I wouldn't have believed it but saw it done on an Audi 80 with the same problems my old 100 had. It supposedly cleans the belts and the valves.
Anyone know why diesel has this effect?