There are thousands of old storage tanks dotting the landscape across the nation with untold gallons of old fuel inside them. How many of them have been checked recently? Probably not that many. If you were to open one up and draw a fuel sample, you could well find the fuel inside looks dark and nasty. Fuel like that is obviously bad.
Visual or “sensory” inspections of stored fuel are better than no inspections at all. But they only go so far. The only thing that will give you a definitive answer to questions about the true condition of stored fuel is analytical fuel testing.
Using a combination of ASTM and other test protocols, you can get objective numerical indicators on essential measures of fuel efficacy like its stability rating, water and sediment content, even how many microbes it has. Analytical testing is also the only way to know the cetane rating and sulfur content of the fuel – essential measures that yield no clues just by looking at them.
It’s recommended that you have analytical fuel testing done on all your stored fuel tanks on an annual basis. Which tests to run? If you’re governed by one of the sets of regulations like ACHA, you should have information on that. If not, there are resources (including here at the Bell blog) that can give you valuable direction on which tests are most important and which tests you can bypass.