There's a pretty decent chance you've made a mess pouring oil before. You know how it goes—you start emptying out a bottle, the dreaded glug begins, and before long, you've got a mess on your hands (and/or valve covers). Thankfully, there's a simple way to avoid this issue that you might not know about.
As the guys at explain, you need to hold your oil bottle by the bottom when pouring. It's counterintuitive, since it's the opposite of how you'd hold a milk bottle, but there's science behind it.
When you pour oil holding the bottle near the lid, air enters and gets trapped in the corner, which causes the glugging. A milk bottle doesn't have this issue since the handle is hollow, giving air a place to be. By holding an oil bottle by the bottom (as seen in the picture above), air won't get trapped, and the oil will flow out smoothly.