I watched my fathers air compressor burn up once when it was connected to an extenstions cord. What happens is, when a compressor first kicks on, the most electricity it will ever draw is with the first revolution of the motor and compressor. The warning to use no extension cords is really just posted for people with little brains. You can use an extention cord as its capacity is greater than the max amps rating for your compressor. At the same time, no matter what a cord say it can handle, the longer it is the less it can handle. So if you connect multiple cords together, you have just created a giant resistor. So what I am trying to say is some compressors won't even turn over if the extension cord.is to small. Others may unknowingly be working harder than normal becuase its not getting enough juice.
A 16 guage cord can handle 10amps of power or just over 1000 watts.
12 guage, 15amps, 1700 watts
10 guage, 20amps, 2300 watts
Also the condition of a cord end or the plug may effect a cords capacity. If it is dirty, corroded or missing some metal. Electricity has to travel through the dirt and corosion.
Ok thats enough of a lesson for now.
Do you fear whats waiting in the woods?