IIRC 10-12 gallons of fuel is the right ratio for a techron bottle.

 

I have always wondered about these products. Another popular one is Lubro Moly. They are a european motor oil and additive company. I have never been able to find any conclusive evidence that any of these products really work that I have confidence are independent.

Also, there is not an abundance refiners around the nation. Costco gas could be purchased from the same refiner as name brand gas in many locations. There are not a lot of places to buy wholesale like 30-40 years ago. I am not even sure that all the name brand gas stations get their gas from their own company across the nation. I can not deal with the lines, so I have never used and do not belong...

 

Refineries will sell gas to both their branded stations and any contracts like Costco, Safeway, etc. But the “additives” are blended in accordingly to contract at the refinery truck loading rack. So for example; Chevron will put Techron into trucks headed for their branded stations, but it’s not likely being added to fuel they sell to non-branded contract suppliers.

I have used Redline products for years and IMO their injector cleaners, like their oils, are all very good. I've had great results using their injector cleaner in my Cummins diesel.

 

I would do all of the above:
Techron every 6mo
Clean throttle bodies