Two checks, and they answer different questions
An outlet keeps the means to do two things on the forecourt, and they are not interchangeable. Confusing them is how a check that proves nothing gets treated as settling the matter.
The density check measures the fuel against the density recorded for that consignment. Every batch arrives with a density at 15°C on its invoice, and the fuel in the tank should still be that density once you correct for the temperature it is actually at. A reading well outside tolerance says something has been added or the wrong product is in the tank. A reading inside it says the bulk composition is what it should be — which is most of what a customer is asking.
The filter paper test is a spot check for the specific case of kerosene or oil in petrol. A few drops on clean filter paper should evaporate away and leave nothing. A stain that persists after the petrol has gone points at something heavier mixed in. It is quick, it is visual, and a customer can watch it happen — which is a large part of its value.
What neither test proves
Neither is a laboratory analysis, and neither will detect a small adulteration or one done with a similar-density product. They are screening checks: they can raise a real problem and they can reassure a reasonable customer, but a disputed result goes to a sample and a laboratory, not to a louder argument on the forecourt.
How to handle the person asking
The checks are the easy part. The part that decides how the next hour goes is what happens around them.
Do it in front of them, without being asked twice. A dealer who performs the check readily has already answered most of the suspicion, and one who hesitates has confirmed it regardless of what the reading says. Read the density out loud against the figure on the record for that batch, so the comparison is visible rather than asserted.
- Keep the density record for the current consignment where staff can reach it, not filed in an office. A check nobody can compare against is theatre.
- Correct for temperature before comparing. Fuel at 38°C reads lighter than the same fuel at 15°C, and the difference is large enough to look like a failed check when nothing is wrong — the density calculator does the correction.
- Record every check: date, time, nozzle, product, density read, temperature, and the batch it was compared against. A log is what turns a later complaint from your word against theirs into a document — the free quality check log does the correction for you.
- If a reading is genuinely out, stop selling from that nozzle before doing anything else, and escalate. Continuing to sell while investigating is the decision that turns a supply problem into your problem.
Most quality disputes are decided before anyone complains
By the time a customer is standing at the office window, the only evidence that helps is evidence you already had. Three habits produce it, and all three are things a well-run outlet does anyway.
Dip and record density at every delivery, not just when something looks wrong — the tanker delivery checklist has the full sequence. Check for water with finding paste on the dip rod at the same time, because water is the contamination most likely to arrive without anyone intending it. And keep the per-tank record continuous, so a change in density has a date attached rather than being discovered as a difference from something remembered.
Frequently asked questions
Can a customer demand a density check?
Asking for one is normal and outlets are expected to be able to do it. Treat it as routine rather than as an accusation — the check takes a few minutes, and a dealer who does it willingly in front of the customer has usually ended the matter there. Refusing, or being unable to, is what escalates.
What does the filter paper test actually detect?
It screens for heavier adulterants in petrol — kerosene or oil. Petrol evaporates off clean filter paper and leaves nothing; anything left behind after it has gone is not petrol. It will not detect adulteration with a similar, volatile product, and it is not quantitative.
My density reading does not match the invoice. Is the fuel adulterated?
Check the temperature first. Density is quoted at 15°C and fuel in an Indian tank rarely is, so an uncorrected reading routinely looks wrong when nothing is. Correct it, then compare. If it is still outside tolerance after correcting, stop selling from that tank and escalate to your supplier rather than working it out on the forecourt.
Should I keep a written log of quality checks?
Yes, and it is worth more than it costs. A dated log of routine checks turns a later complaint from an argument into a record, and it is the first thing an inspection asks for. Log the routine ones too, not only the ones a customer prompted — a log that only exists when there was a dispute reads as a log kept for disputes.