Originally Posted by demarpaint
When I did it I added at the gas station then pumped the gas. I know by the fuel gauge if I need 10 or 15 gallons of fuel. So I'd add either 2 ounces or 3 and pump to a round $ figure ~ 10 or 15 gallons of gas. I might have been a hair over or under on the mix.
I also do it this way. I purchased several 4oz plastic bottles and put 3oz of TC-W3 in each of them, when my fuel gauge reaches 1/4 (21 gal gas tank) I dump the oil in and then gas-up (approx. 15 gallons). IMO this probably mixes the oil with the gas better.
I have been using TC-W3 for about 9 years, soon after reading about it in the LS1 forum
https://www.ls1.com/forums/f48/been-testing-oil-91206/
I was initially skeptical, but several things soon made me a believer... my gas mileage improved by about 5%, the slight buzzing noise I heard from the fuel pump went away, the injector ticking quieted down, and the engine ran (and still runs) very smooth and quiet. It has been stated that it also helps to counteract the negative affects of E10. The 5% gas mileage improvement doesn't sound like much, but it does pay for the TC-W3, and then some.
My Toyota is now 14 years old and has over 170k miles on it and it still has the original cat, so I don't think that the TC-W3 has had any negative impact on it's life span. Also, I have not had to replace any injectors, O2 sensors, valves, seals, the fuel pump, or any other fuel system or emission system component.
I buy the cheapest dino TC-W3, usually SuperTech. I did try synthetic TC-W3 for a few months, but the more expensive oil doesn't appear to do any better than the cheaper oil.
In the LS1 forum there is universal agreement that mixing 1 oz of oil to 5 gal of gas is the ratio that provides the maximum benefits, mixing half this amount of oil will not likely provide any noticeable benefits. StevieC, if you mix at this ratio, given the number of miles that you drive, you should be able to report back on any noticeable (positive or negative) benefits in fairly short order.