That’s why you’ve been filling it with premium gasoline all these years. “Unless your vehicle manufacturer says premium is required — not recommended, but required — we’ve found no advantage to using premium fuel,” Shupe said. In California, premium gas is labeled 91 octane, midgrade is 89, and regular is 87. (The exception is older cars with engine knock, which can potentially benefit from midgrade gas.) Any grade of gasoline — regular, midgrade, premium — can be Top Tier.

Source: Los Angeles Times June 01, 2022 18:18 UTC