The Tundra requires that the oil change be done at 5,000 miles for a flex-fuel vehicle (mine is), with a 2,500 mile interval for severe service in a flex-fuel vehicle. I do run E85 fairly often (it's $1.79 here on base, and while my MPG declines, my cost per mile is cheaper on E85 than gasoline). I mentioned this to Blackstone, and it's the reason that I wanted a UOA. I had gone a bit over Toyota's required OCI, and I was running E85 often.
The truck also specifies a 0W20 (TGMO) and for the first two years that I owned it, Toyota changed the oil. Interestingly, our local dealer in VB used Valvoline 0W20, not the TGMO. For this change, the first that I had done, I got a great deal on the Pennzoil Ultra Platinum 5W30, so I ran that with a genuine Toyota filter. I've still got a couple of jugs of the 5W30 Ultra Platinum, so it won't be back on 0W20 for a while...
The truck also specifies a 0W20 (TGMO) and for the first two years that I owned it, Toyota changed the oil. Interestingly, our local dealer in VB used Valvoline 0W20, not the TGMO. For this change, the first that I had done, I got a great deal on the Pennzoil Ultra Platinum 5W30, so I ran that with a genuine Toyota filter. I've still got a couple of jugs of the 5W30 Ultra Platinum, so it won't be back on 0W20 for a while...