I just grabbed about 20 quarts of this stuff from Walmart which has the 10-30 and 10-40 on closeout at $1.00 a quart. It's the synthetic blend. Is this stuff just as good as the normal dino stuff out there like Pennzoil yb, mobil 5000, valvoline premium etc etc... If so, I think I'll go back and grab the rest of the 10-30 they had. I have a 2004 Yukon Denali and 2002 Nissan Altima 2.5s. Live in Arizona so I don't see any problem with the 10-30's as opposed to 5-30's. Always use a Wix filter... What's the norm on an oil like this, around 5,000 miles before changing it out? Thanks guys.