Diesel theft on farms: warning signs and how to stop it

The clearest sign of diesel theft on a farm is a missing diesel that you cannot explain: the tank holds less than your records say it should, or a vehicle uses more than it did in the previous month while doing the same amount of work. Some missing diesel proves nothing, because a leak, a metering error or a missed entry looks identical. However a pattern that repeats is what tells you to investigate.

The good news is that you do not need cameras everywhere to deal with it. Locks, knowing who was at the pump, a record of every litre and a regular tank check will stop most losses, and will show you quickly if something is still leaking away.

What are the warning signs of diesel theft on a farm?

Look for these, ideally in your records rather than by gut feel:

• The tank is lower than the book says. You measure the tank and it holds fewer litres than deliveries minus litres logged would suggest, and it happens again next month.
• A vehicle's consumption jumps. The same tractor doing similar work suddenly uses more litres per hour, or a bakkie uses more per 100 km.
• Pump readings that do not add up. The cumulative pump meter has changed by more litres than were written down as dispensed.
• Refuels with no matching entry. The meter moved, but there is no log for it, or log entries are bunched together at the end of the week.
• Deliveries that look short. The tank level rose by less than the delivery note says.
• Fuel used at odd times. Refuels at night, on weekends or on days when the vehicle was not working.
• Signs at the tank. A damaged lock or hose, drips on the ground, or a tank that is open when it should not be.

Not one of these is proof. Each has an innocent explanation, which is why the next sections matter as much as the warning signs.

How do I stop diesel theft on my farm?

Think in layers: make taking diesel hard, make taking it visible, and make it easy to notice quickly.

1. Secure the tank and the pump

• Keep the tank, pump and nozzle locked when nobody is fuelling. Lock the pump or its isolating valve, not just the hose.
• Fit a lockable filler cap and, where it suits your tank, an anti-siphon device. ServiceLink SA lists lockable dispensing, anti-siphon devices, fencing, lighting and cameras among its recommended controls.
• Put the tank where it can be seen from the house or yard, with some lighting.
• Keep spare keys to a minimum and know who has each one.

2. Decide who may refuel, and be able to tell them apart

Shared access is the weak point. If three people use one key and one logbook, you can never say who was there. Limit fuelling to named people, and where you can, give each one their own login rather than one shared password.

3. Log every refuel, with the cumulative pump reading

Each time diesel leaves the tank, write down the date, vehicle, litres, the cumulative pump meter reading, the odometer or hour meter, the activity and who made the refuel. The cumulative pump reading is the key one: the difference between two readings is what really left the tank, which you can compare with what was written down. For the layout of a good record, see how to keep a farm diesel logbook.

4. Measure the tank regularly and reconcile

Measure what is actually in the tank and compare it with what the records say should be there. Random, unannounced checks add to the deterrent. How to measure is covered in how to measure diesel tank levels.

5. Check every delivery

Do not leave the driver to fill the tank alone. Check the tank before and after, compare the rise in volume with the litres on the delivery note, and keep the note.

6. Check consumption per vehicle

Compare each machine with its own history: litres per hour for tractors and harvesters, litres per 100 km for bakkies and trucks. Compare it against its own normal for the same kind of work, because ploughing and carting are different. A machine that drifts away from its own history is worth a look, and so is a fuel card used outside normal routes.

Why does the tank not match the records, if it is not theft?

Rule these out first, because they are far more common than theft:

• An unlogged refuel, such as a jerrycan or a pump that was filled in a hurry.
• A wrong dip or the wrong chart. The measurement was off.
• Temperature. Diesel expands as it warms. The Logistics Cluster notes that diesel at 25°C takes up about 2.5% more volume than at 0°C, so readings taken at different times of day are not strictly comparable. Rather take measurements at a specified time to ensure comparable results.
• Pump meter error Some pump meter readings can have some 'noise'.
• A leak in a hose, fitting, valve or the tank itself. Look for wet patches and damp ground.
• Evaporation and spills when filling.

How do I investigate a discrepancy without accusing anyone?

Treat it as a question about the system, not about a person, until the evidence says otherwise. Accusing someone wrongly can result in conflict.

1. Measure again, the same way, and note the time and temperature.
2. Check the paperwork. Are all deliveries and issues entered? Is there an entry on the wrong tank or the wrong date?
3. Check the equipment. Pump meter, hoses, valves, tank base.
4. Find when the gap opened. With regular readings you can narrow it to a week, and then to who had access that week.
5. Tighten the controls and watch. Lock up, name the people who may refuel, and measure again a week later. If the gap stops, you have learnt something without an accusation.
6. Talk to people in neutral terms. Say the numbers do not match and you are trying to find out why. Ask what they saw.
7. If you do suspect theft, keep your records, speak to the SAPS and take advice before disciplinary action. Employment law requires a fair process. That is general information, not legal advice.

Can software help?

It can make the gap visible sooner. AgriTrekker, for example, logs refuels and tank measurements from a phone (even without signal), compares the litres pumped from a tank with the litres logged into vehicles and with dip measurements, marks entries that do not add up, and keeps the history of any edited entry. It shows you where to look; it does not tell you who. The judgement stays with you.

FAQ

How can I tell if someone is stealing diesel on my farm?

Compare the tank, the pump meter and your logs. If the tank is consistently lower than the records say it should be, or the pump meter moves by more litres than are logged, and you have ruled out leaks and measuring error, theft is one possibility. A single gap is not enough; look for a pattern over several weeks.

What is the best way to stop fuel theft on a farm?

No single measure does it. The combination that works is a locked tank and pump, named people who may refuel, a log of every fill with the pump reading, regular tank measurements and checks on every delivery.

How often should I check my diesel tank?

Often enough to catch a problem while you can still trace it. Monthly is a minimum; weekly on a large or busy operation. Unannounced checks help.

Should I install cameras?

They can help as a deterrent and as evidence, but they do not replace records. Without a log and a tank check you would not know what to look back at.

What should I do if I think a worker is stealing diesel?

Do not confront anyone on suspicion alone. Collect the readings and logs first, tighten access, and remeasure. If the evidence points to theft, take advice and follow a fair process before acting.