Can I use E-85 fuel in my 2006 Mitsubishi Endeavor LS?

Absolutely NOT! I can't believe someone would recommend that. The Endeavor is especailly sensitive to fuel. Not only should you NOT run E-85, but you should use premium. The 3.8L has many ways to retard timing, but low grade fuel will still cause significant spark knock. E-85 would be a disaster and void your warranty.