The right fuel depends on what the owner manual says. If your car requires premium gas, use it. If it only recommends premium, regular gas may work, but you may lose some power, efficiency, or smoothness.
Here’s what you need to know:
| Fuel type | What it usually means |
|---|---|
| Premium required | Use premium every time |
| Premium recommended | Regular may work, but performance can drop |
| Regular allowed | Premium usually does not add much value |
Premium gas has a higher octane rating. That helps prevent engine knock, which is unwanted combustion inside the engine. Many modern engines are designed to run on a certain octane level, and they adjust timing to protect the engine if lower-grade fuel is used. That protection can come with a small hit to power or fuel economy.
For most drivers, premium gas is not worth it unless the engine is tuned for it. If the manual says premium is required, skipping it can raise the risk of poor performance and long-term engine problems. If the manual says premium is only recommended, you can usually test regular gas and see whether the car runs well enough for your needs.
A good rule: look for the octane number on the fuel door or in the owner manual. Most regular gas is 87 octane, while premium is usually 91 or 93 octane. If your engine needs premium, the small extra fuel cost is usually cheaper than the risk of using the wrong fuel.
According to AAA’s 2025 Your Driving Costs study, fuel is one of the main ownership costs, so even a small fuel-price difference adds up over a year. For drivers who fill up often, choosing premium when the engine does not need it can increase annual fuel spending without giving much back in daily use.
If you want to decide fast, use this checklist:
- Check the fuel cap or owner manual.
- If premium is required, buy premium.
- If premium is recommended, try regular and watch for knock, rough idle, or lower mpg.
- If your driving is mostly city trips and short errands, save premium for cases where the manual truly calls for it.
If you want help comparing fuel costs, Sidekick can estimate how much premium gas adds to your yearly ownership budget.
Bottom line
Premium gas is worth it only when your engine needs it. If your car does not require premium, regular gas usually makes more financial sense.