Higher octane gasoline is designed to help prevent engine knock. This phenomenon isn't typically harmful to your engine if it happens occasionally, but repeated engine knock can speed up wear and tear.

Is 87-octane bad for your car?

Let's start with the easy one. Most cars on the road recommend a standard grade 87 or 89. Premium gas 90-93 is completely okay to put in a standard vehicle. Car experts say there is no risk of damage to a standard car using premium fuel.

What happens if you put 87 instead of 91?

“Use premium unleaded gasoline with a posted octane rating of 91 or higher. If the octane rating is less than 91, you could damage the engine and may void your vehicle warranty. ... They usually warn that using lower-octane gas could reduce performance and fuel economy.