WE'RE BACK...

Okay, so it's been awhile since I posted.  The firewall issue has been resolved.  So here's a challenge:

You need to fill the sump of a helicopter engine with exactly 4 gallons of 2190 TEP oil.  The trouble is, the only things you have available, aside from the helo itself, is a 200 gallon tank of oil, a 5 gallon can, and a 3 gallon can.   Although you can measure exactly 3 or 5 gallons precisely, you can not “eyeball” or estimate any other amount.  How do measure exactly 4 gallons?

This challenge will expire at 0730, Tuesday, 16 April.  Good luck!

"Looks like about four gallons to me."