Take samples with clean hands! For fuels, the standard calls for a maximum of 10 ppm of sulfur in the fuel. Oils and lubricants, which are soiled by the mechanic's hands, have several thousand/thousands ppm of sulfur each. All it takes is a minor soiling of the cap and the sample tested will be disqualified (outside the standard).

Take the sample right away into a clean container.

If you are taking a sample from a gas station or when delivering fuel to a plant, do not take a sample right away. The ends of the fuel gun always collect impurities that will falsify the result. Pour the first few liters normally into the tank / fuel tank. The same for sink plugs and faucets from machinery and equipment.

It will not hurt to rinse, theoretically clean, the container with tested fuel or oil. This will ensure that any contamination is not the result of a dirty container.

Sample in the presence of all parties involved. If this is not possible document the collection on film until the bottle is capped

Get three one-liter samples from the same location into bottles with numbered seals.

Once you have taken the samples, immediately cap them, describe them and fill out a sampling protocol that includes seal numbers and signatures showing agreement that the procedure was done correctly and all the bottles contain exactly the same fuel/oil.

Send one sample to us, leave another for yourself, and give the third to the other party or, if that's not possible, also keep it with you.