I have been lurking here for awhile but this is my first post. I used to own a F150 Triton engine. It required 5w-20. right before I sent it back to the dealer when the lease ended, I bought 2 cases of Motocraft 5w 20 semi synthetic. (Stupid is as stupid does). I got a Ford Explorer 6 cylinder and it uses 5w-30. Can I use the 5/20 in the explorer? Will it do any damage? Is it enough protection at high Temps? or should I find a f-150 owner and give him a present. One guy told me to use it half 5w-20 to half 5w-30. I was told long a go to not mix grades what do you guys think? I have 20 qts, needs to get out of the garage.