Mobil 1 gear oil question

I use 89 in my grasshopper during peak growing season. In the off season I run ethonal free. I have been told as long as 89 doesn't sit to long it's fine to run. I put a little fuel treatment in it too.

 

So it seems as long as I change the oil out at 30,000 it doesn't really matter...good to know thanks! On another I used ethanol free 91 octane gas from upstate NY and increased my mpg's significantly. I was towing over the weekend for 3 days and the same load and trailer 1st day Shell 87 octane 18.4 @ 60 miles an hour 2nd day Shell 93 octane 19.2 @ 60 miles an hour and 3rd day Stewart's 91 octane ethanol free 20.7 @ 60 miles an hour. In my opinion the added cost is worth every penny. I can't physically can't prove that the truck ran better but I feel the ethanol free gas improved throttle response and just felt smoother.

 

All I hear is that you have to reprogram the computer to see any benefit from higher octane gas.

 

I am going to continue testing the possibility of better mpg's from a higher octane gas but it does not come close to ethanol free gas. The 93 octane does make my taco run quieter and smoother but again I have no way of proving this. I guess you can't believe everything you hear...