After using this, it soon becomes clear why the dumpy shape of our Screwfix Best Buy is such a good idea. When less than half full, this slender design is prone to toppling over, and you have to hold it while working the pump. However, the 6.5-litre capacity can’t be argued with, nor can the length of the tubes supplied. But the dipstick tube is compact and not especially flexible, meaning curves could pose a problem.