using diesel to flush the engine is a major mistake.

If you feel you need to flush it out, just change the oil, then change it a day later.

Proper oil for diesel engines is already full of detergents. (If its a diesel car) otherwise just change the oil more often.

Diesel attacks the material used in bearings.

Its an old mechanics wives tale - it might seem to work, but its not good.

I notice he dismissed crud falling to the bottom of the sump - thats exactly what will happen - and it will gather around the oil pickup, where it will stay lodged, and eventually block the oil pickup, causing loss of oil pressure. It cant get sucked through the gauze, so it collects around the outside

have seen it loads of times. normally its instant gasket that gets dislodged though!

he also seems to think that oil doesnt circulate round the turbos unless they are spooled up - the oil is ALWAYS circulating round them. Depending on what sort of bearings are in the turbo, it will wreck them too.

Diesel OIL will work as a flush though, due to all the detergents. Run it for a few hundred miles.

FWIW though, no need to do a flush unless you have used hair conditioner instead of oil at the last fillup! Modern stuff is pretty good

I flushed with diesel in an old VW bus with stuck  hydralic lifters and it worked fine. (I added 4 liters diesel and cranked engine until oilpressure light went out and then drained and put new oil in) Tried just chainging the oil first but it did not help but with a flush the lifters unstuck and the car continued to run well for a long time.