My husband has worked in the car industry for over a decade. And one of the most important pieces of advice that he has shared with me is to avoid what’s become a very common practice – “topping off” your gas tank at the gas station.

I’ll admit – I used to do this a lot. But, not anymore: According to him and many other car experts, this is a big “no no,” and could lead to expensive problems with your car!

Read more: Why you shouldn’t let your gas tank run this low

Damage to the charcoal filter

“By topping your fuel tank off, it can either overwhelm your evaporative system and break something or cause a hazardous leak by the excess pressure in the system,” says Ed Nemphos, owner of Brentwood Automotive in Baltimore.

Topping off your gas tank can cause pressure to build in the tank and flood the carbon filter vapor collection system, only meant for vapor. Subsequently, this overflow can affect your car’s performance and could possibly damage the engine.

“When we overfill the tank, it sends all of the excessive fuel to the evaporation/charcoal canister and kills the life of that canister,” said Joel Carruso of Caruso’s Auto Repair in New York.

Carbon filter canisters cost anywhere from $200 to $1,500 — not to mention the cost of an entire engine!

Wasted gas, wasted money

According to the EPA, once a gas tank is full, there is no way to fit any more gas in the tank. Gas stations are equipped with a vapor recovery system so that if a tank is full, the pump will pull the extra gas you’re trying to pump into your car back into the station’s tanks. This is a safety precaution to ensure excess vapors will not escape into the environment.

So, even though you are paying for more gas, if your tank is full, the excess will go right back to the station anyway!


Read more: Purple is an on-demand app that comes to fill up your gas tank

Avoid harm to the environment

In addition, topping off tha tank can result in a greater chance that gas is spilled onto the ground, and these gasoline spills can contribute to bad ozone days as determined by the Air Quality Index.

If you happen to damage your car’s vapor recovery system by topping off your tank, it also won’t be able to protect people and the environment from harmful vapors caused by improperly processed gasoline.

So, consider this a friendly reminder to think twice before you top off your gas tank — you could avoid hefty car repairs, avoid harming the environment and keep more money in your pocket!

Is detergent gas better for your car?