Bad quality gas

We often have folks with theories about the best gas for their Prius, E0, Premium, top tier, etc.

The best gas is from the most used storage tank in your town, the crud does not have time to settle to the bottom. So buy unleaded E10 regular at the busiest station. If it is top tier great. it is wildly unlikely that more premium or E0 is sold in your town then E10 regular, so avoid those. Premium may have very minor lower MPG than regular, E0 will in theory get 3% better MPG than regular, but both are likelier to be bad gas. YMMV.

 

Yep, always beware of those smaller, Mom and Pop stations. Many years ago, I was a stockboy in one with gas pumps and our nighttime guy was in charge of taking manual tank measurements and we had a very long wooden pole to stick down the tanks and read the marks on the pole. To make it easier, the nighttime guy would coat the wooden pole with a bunch of baby powder. I asked him if all that powder in the tanks hurt car engines and he shrugged and said he didn't care. I worked there and never filled up for that reason!
We have a very busy Top Tier station down the road...sometimes it's a few cents higher than others around but I feel it's worth it.

 

You should not notice an immediate difference when you add bad gas, nor should you notice it immediately when you add good gas. It takes a while for the bad gas to make it's way through the car's plumbing,

When I was young I bought the cheapest gas that I could find. My two stroke 90 CC single cylinder motorbike** had a small 1.6 gallon tank and used oil injection to lubricate the cylinder. One day it started to run erratically about 30 minutes after refueling. I pulled the plug while parked on the shoulder of the road and found it was fouled. I cleaned the plug and was able to drive several miles before it fouled again. By draining the float bowl through a paper napkin, I was able to see water droplets in the gas. The water was shorting out the plug and left the unburned oil and gas coating the interior of the cylinder head. To get it to run I had to drain the gas into a coffee cup found in the gutter, filtered through a piece of cloth cut from my tee shirt and then poured back into the gas tank.

TLDR: Bad gas takes a little while to impact the car, and adding good gas does very little until all the bad gas is flushed from the system.

**The Suzuki TC90 blazer was a neat little 2 stroke trail / street bike in the 1970s. It had a dual range 8 speed transmission so that you could do 60 on the open road with one setting and climb a steep trail at 2 mph with the off road setting.

 

Some cars are more sensitive to gasoline quality than others. Driving a new Ford Ranger for the past two years was an eye-opener. No more Sam’s Club fuel for me! The Ranger is now gone from my garage, and I am even more of a proponent of Top Tier fuel for all of our cars, even if they don’t show immediate symptoms from lesser-quality fuel.