What gasoline should i use

If this is the case, you may want to just go with the cheaper gas, or experiment and see if the amount you make up in fuel economy and the difference in power is appreciable enough to justify the higher cost of the premium fuel. What about the other way?

Does higher octane gas ever help a car not designed for it? If there is no premium recommendation for your car, putting in higher octane gas will not improve fuel economy, and you are just throwing away money. If your vehicle calls for diesel fuel, you have a diesel engine, which is an entirely different system. There is no negotiating fuel if you have a diesel engine.

You need to fill it with diesel fuel and nothing else. If you put regular or premium unleaded gasoline in a diesel engine, not only will the vehicle not run, you can do catastrophic damage to the engine. If you are driving through very high-altitude places, you may see gas stations offering lower-octane gasoline than you expect. For example, you may see octane gas advertised.

If you are used to always just getting the least expensive gas at the station, you may be tempted to use lower octane gas than you are used to. Older cars were able to operate with lower than normal octanes at high altitudes because of the thinner air, but this does not hold with modern fuel-injection engines. Therefore, if you usually use octane gas, going for the cheapest option if it is lower than 87 is not recommended. It is better for your car to use 87, 88 or even octane gas than to go too low.

Your car, your rules. Type: Car Ownership. Published: January 11, So, what's the difference between premium and regular gas? If your car only recommends premium, the choice is yours. Related Articles See all. See all. TrueCar logo. Similar to the BMW, the Dodge's gains on the dyno 14 horsepower and 23 lb-ft of torque translated into negligible improvement in our real-world acceleration testing.

Saddled with elephantine heft and eager to spin its rear all-season tires at launch, the Charger posted the same 4. At triple-digit speeds, the higher power on 93 octane gave the Charger an advantage measured in tenths of a second. The Dodge also posted a 0. Just as important, the bellicose roar of the iron-block Hemi and the Charger's ability to reduce its rear tires to jungle-gym ground cover are unaffected by the fuel in the tank.

While Ford's EcoBoost F stands out as an obvious exception, the Dodge Charger's numbers make for a tidy summary of our findings.

If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants. How your engine constantly invites and silences engine knock to estimate a fuel's octane rating.

Your car doesn't know the octane rating of the fuel in its tank. Instead, the engine controller calculates an inferred octane with closed-loop logic that continuously advances the ignition timing until it detects knock, which occurs when a portion of the fuel-air mixture ignites before the spark-plug-initiated flame front reaches it.

The further the computer can advance the timing without provoking knock, the higher the octane rating. During knock, the flame front travels through the combustion chamber up to 10 times quicker than the normal spark-initiated flame front. Left unchecked, these pressure waves can damage the head gasket, pistons, or cylinder head. But the occasional brief knock is a useful tool for checking that the engine is operating efficiently.

It's detected with one or more knock sensors bolted to the block to sense the oscillations created by the pressure waves with a typical frequency between 7 and 16 kilohertz. Stephen Russ, senior technical leader for gas engines at Ford, says this normal knock is usually detected and addressed within one or two combustion cycles and poses no threat to the engine.

New Cars. Buyer's Guide. Type keyword s to search. Today's Top Stories. Marc Urbano Car and Driver. Here are a handful of helpful facts to guide your choice at the pump:. Engineers at auto manufacturers prescribe premium gas because certain kinds of engines operate optimally with higher-octane fuel. Cars that require premium gasoline have high-compression engines, turbochargers, and other high-performance aspects. Your car can get plaque build-up from gasoline deposits.

If you have an older, heavier car, SUV, or truck with high-performance engines and you are experiencing engine knock, try using premium gas for a few fills to see if that fixes the problem, even if the vehicle does not call for it.

What qualifies as premium gas varies from state to state. So pay attention if you are on a cross-country road-trip or crossing state lines. One state may require a minimum octane rating of 92 to be considered premium, while another may only require Gas stations in the United States generally offer three octane grades: regular usually 87 octane , mid-grade usually 89 octane , and premium usually 91 or Check the sticker on the pump to know which you are getting.