Is Cheap Gas Bad for Your Car?

“Bad gasoline” is the standard verdict of servicemen who are forced to replace spark plugs reddened from soot ahead of time. But how is this gas formed and whether it can harm the engine? Let’s find out whether cheap gas is bad for your car and how to select the fuel to get the best performance in the long run.

Gasoline must have strictly fixed parameters to ensure the stable operation of the engine – first of all, the octane number. But the properties of the oil from which gasoline is obtained range fairly wide. Refineries use special additives – this is much cheaper than changing the processing technology for each batch of oil. Modern gasoline contains a variety of additives – antioxidant, antiwear, anti-icing, and anti-smoke.

The most effective and cheap octane-boosting (anti-knock) additives are organic lead compounds – tetraethyl lead and tetramethyl lead. Their use in developed countries was abandoned back in the mid-90s, with the introduction of Euro 2 standards (ethyl liquid is the poison, and leaded gasoline combustion products very quickly disable the catalytic converter). In the United States, preparations for a ban on lead compounds were thorough – they even had to modernize oil refining technology and engine design. The share of additives in gasoline has decreased tenfold, and instead of lead, methyl tertiary butyl ether (MTBE) has been used. In small doses, it is practically harmless to the engine.

The Ethyl company (its name has been preserved since the heyday of tetraethyl lead) proposed additives based on manganese. In a relatively small amount (18 mg / l versus 150 mg / l for tetraethyl lead) they can increase the octane number of a liter of gasoline by one unit. Such additives are still widely used in the USA.

But iron-based antiknock agents, ferrocenes, which were allowed in the days of tetraethyl lead, were immediately rejected by car factories. The reason is simple: iron-containing additives significantly reduce the life of catalytic converters, spark plugs, and oxygen sensors (lambda probes). The decision is almost ripe: ban ferrocenes and allow manganese and MTBE.

Thanks to advances in engine technology, modern cars utilize onboard computers that adjust for variations in fuel, so using cheap gas occasionally won’t damage your engine at once. The difference between off-brand and Top Tier gas comes down to the degree of additives that afford more protection for your motor.

It all depends on the engine type. When a premium fuel engine runs on regular gas, there’s a risk of fuel mix combustion before the spark plug lights up. This causes knocking, which is likely to damage the motor.

Premium gas may provide more miles per gallon than a regular one, as it always contains extra detergents that can increase fuel efficiency. However, the difference is not that significant. If you want to get more miles per gallon, it is worth considering a more fuel-efficient car model.

In large cities like Indianapolis, most of the filling stations are owned by large companies that value their reputation and sell high-quality gasoline. But at “No-name” gas stations, the risk of running into ferrocene gasoline is very high. This can be determined only later – when the candles turn red from soot and the engine stops pulling. And it is impossible to prove that it was at this gas station that you filled low-quality fuel and that its owners must pay for the repair of the engine and the replacement of the converter.

Both cheap and expensive gas make cars run the same if you are sure of the quality. In the end, choosing the most expensive gas brand does not make sense if you don’t skip routine maintenance and use high-quality cleaning supplies.

Make sure your car engine is in good condition – schedule your visit to the Indy Auto Man service center for professional diagnostics!