Hey Johnny,this may be a super dumb noob-ish posted a zillion and one times question,but what`s the difference between GF4 and GF5 oil? Reason I ask is that I saw at Walmart yesterday that they finally have the new label GF5 Pennzoil yb 20W50 :^)I had to buy some ATF for my power steering. It was a lil low. Guess it`s about time seeing it`s 14 year old fluid,haha! I drained it and refilled it with Pennzoil Dexron ATF. The oil bug almost bit me as I came VERY close to buying 5 quarts of it (the GF 5 yb 20W50).