Submission
A note on sabotage of heavy machinery: please don’t waste your time messing with fuel or filtration systems. The idea of adding something to a fuel tank is (unfortunately) a widely known sabotage technique that the average person might think of, but it is most likely ineffective on modern vehicles or heavy equipment. Filtration systems are designed to filter out contaminants.
Bleach is typically added to engine oil. The rule of thumb is to add 10 fluid ounces of bleach per gallon of engine oil. This equals one gallon of bleach per 12.8 gallons of engine oil, which should be enough for an average-sized piece of heavy machinery. Larger machines will need more, smaller machines will need less. You may want to look up the specifications of the particular models of equipment on site to be sure of their fluid capacities.
The fuel is probably the least sensitive fluid in the machine; in addition to engine oil, try messing with the transmission fluid, hydraulic fluid, or exhaust fluid. For starter ideas on what to add to these fluids, check out this old Dear Ned Ludd column. [https://efmechanicsguild.wordpress.com/2016/09/06/a-nice-dear-ned-ludd-from-an-ef-journal-last-year/]
Have fun out there!