Bad Petrol

Went to Shell Garage in Phoenix Palmview and filled a full tank of petrol on Sunday the 27 August 2023 a little after 5pm. I proceeded home and the next morning which was today the 28th August 2023, I drove to work and parked my car. The car is parked off the whole day until it's time to go home. Driving back home the car had lost 2 bars of the full tank that I had filled the previous day. This is the first time that such has ever happened, I fill my car at different Shell service stations and have previously filled a full tank and this has never happened before. It usually takes about 3 days of going to and from work after I have filled a full tank of petrol for the gauge to go down one bar. This instance it went from 8 bars to 6 bars in a day.