Nah, no codes were thrown.
A 1-2 mpg increase isn't all that great, but hey, i figured i'd try it out. It'll eventually pay itself off.

 

oh yeah! 1-2 in these rigs isnt bad at all.
Im glad you chimed in with a real life test because I've always been very skeptical of these things.

 

Thanks for the data, Bama Boy !!

I may have to say no on buying it when you said it causes slower warm-up cos' I am in Toronto. Today is -19C (or -2F) here.

 

Yep no problem. I just start my Disco up about 10 minutes early now and that corrects my slower-warm up lol.

I just did a fill-up, and got 13.94 mpg.
I got 224 miles out of 16.064 Gallons over a period of 12 days.
I had 24 highway miles, and 200 city miles. (My school is literally 2 exits down the highway).
Also i start my Disco up 10 minutes early every day, which gives me about 120 minutes of idle on that tank.

I'm comparing this to my previous fill-ups in December when i was getting about 12.5 mpg and traveling the same route.
13.94 compared to 12.5? I'll take it.