my guess to where you got oil containers? you own a ford? or like me a home depot john deere ride on lawn mower, 1 liter per hour...and it is 4 years old..
2x4 are 8 feet so for using as much wood as possible i would think it is 20 wide and probably 22 long some built with a " lean too " on the end. it is a piece as an after thought when they realized the bumper would not fit in the garage so they built a 4 foot piece on the end to make do...