I have this on/off performance issues especially with my diesel fed vehicles. I attribute it to 'dirty diesel' as they usually occur shortly after refuelling.

Has anybody ever stumbled on some info about DIY testing for diesel contamination.

At least there is this simple 'Blot Test' for petrol:

"Place a few drops of petrol on a blotting paper and let the fuel evaporate, it should not leave any mark on the blotting paper, otherwise it is adulterated".

For diesel, I have a quick pass on 'specific gravity test' (not so simple to do) used by Fuel stations to estimate the volume of their diesel at different temperatures, looking for possible 'ghost delivery'.

The Depot could have supplied them a particular volume of diesel only to find out later that some is missing due to contraction, as the station fuel tank is a lot colder than the delivery truck tank.

Any practical solution to avoid dirty fuels, simple gadgets or workarounds.