I was reading that post on the 5w20, and what ford recommends. But, I've been using 10w40 oil in my truck ever since I got it. I believe when I had other shops do the oil change they also used 10w40 (at least that is what the stickers said). So, is there anything wrong with using this oil? I also live in Arizona, so it does get pretty hot. I'm also supercharged if that makes a difference. Thanks for any info.

 

Anybody?

 

Mineral or synthetic? If mineral, it's probably better in that climate, as the heavier weight oil has more viscosity when it heats up; but if you're using synthetic, you won't be doing any better with it (maybe more strain and parasitic losses than anything else), but again, in a hot climate I'm sure you're just fine.