Many injector cleaners consist mainly of kerosene,so yes,a little paraffin would be a cleaner,but also yes,lots will get you in major trouble with the VOSA.
And if you think it doesnt happen......2 weeks ago VOSA had a mobile test station on the A30 dual carraigeway with police motorbikes cruising up and down both sides picking up custom and escorting them to the layby where the poor sods were took apart by the men with clipboards and ,yes,had their tanks dipped.
The really,REALLY great bit is that they dont bother with the smoke belching eastern euro trucks as its a waste of their (police and VOSA) time because the drivers will be out of the country before any court dates and so the cases become non-cost-effective.
Like we need more stealth taxes.