The supplier I buy from supply companies who use several hundred thousand liters per month in industrial furnaces and the like. The supplier has each new delivery tested by the Sasol lab connected to UCT. They avoid e.g. the Engen product as it has a lower calorific value. Their good name is at stake as the clients will notice that they have to use more liters per hour to achieve the same result or if their furnaces coke up faster.
I have had two bad cans of Laurel which caused my lanterns, especially Tilleys and Coleman table lamps to burn brightly for the first few minutes and then get dimmer and redder and then start gently flaming with blackened mantles.
Using this paraffin cured them immediately.
I have also used JetA-1 which smells different but burns quite well. Model plane hobby shop sold it for R9,60 per liter.