Originally Posted by snrusnak
Yes the 91 tune with 93 octane is ok. And should be ok for towing as well, at least for light-medium loads. Not sure how that'd go with heavy loads.
I'd stop the lucas though. You don't need anything additional to the fuel coming out of the pump. A treatment of seafoam or something similar occasionally will help keep the fuel system clean, but don't waste the money using it constantly. It might even effect the octane rating of the fuel.
I am towing a heavy load, so it sounds like I just need to discontinue and go to stock...
The only reason I have continued using it is I get about 3/4mpg gain using it; i will stop using for now and see what I can figure out, but financially I come out ahead with it in the tank at 4-5oz/tank.