I have never used Fuel Injector Cleaner before and I have about 95k on my car. Do I just buy a case of this and pour it in my gas tank or is there anything else i have to do? How often do you add this to your gas, once an oil change? Thanks

 

Read the instructions on the bottle scammer.

 

I would pour only 1 bottle in, not a case.

 

with our tiny tanks, i would just do a half bottle. then after another 1-2k put 1/4 bottle then same thing again in another 2k miles

 

do these things really work or necessary?

i don't know how often stock injectors need to be serviced.. but wouldn't it be better top just have them re-calibrated/cleaned if thats the case, replace seals..