Okay, Perhaps I missed it in the 5W/20 Myths thread, but just how much MPG gain does 5W/20 offer over 5W/30? I used about a quart and a half of oil over a 3000 mile period in my 2005 Dodge Grand Caravan (3.8 V6). I use Havoline 5W/20. I was thinking of switching to Havoline 5W/30 on next OC to see if that didn't improve things. Curious how it will affect MPG.