I'm sorry, I read the rebate, then I read the rebate form you have to fill out, and I found it to be very straight forward and easy to understand, and all the print appeared to be the same size. Here are the conditions as copied and pasted from the form.
Conditions
Because fuel economy improvement is achieved after first-time use of P.i. in a vehicle with accumulated deposits, the P.i. money-back
guarantee is limited to vehicles with a minimum of 25,000 miles. Those vehicles must not have been previously treated with P.i. and must not
have undergone any fuel system or fuel injector cleaning or replacement procedure. P.i. must be used with a full tank of gas, and that tank
must be run until near-empty. Fuel economy will then be measured after the following tankful of gas, and if no improvement is realized the
money-back guarantee applies. P.i. must be used in accordance with the treat rates listed on the bottle. This offer is limited to one refund per
customer and is good through May 31, 2009.