Putting REC 90 gasoline in a car that requires regular unleaded is not recommended and can be harmful. REC 90 is a high-octane, ethanol-free fuel typically intended for small engines, marine equipment, and recreational vehicles. Using it in a modern car designed for standard fuel offers no benefits and can lead to performance issues and potential damage over time. The key problem is that REC 90 often lacks the detergent additives required by the EPA for modern automobile engines. These additives are crucial for keeping fuel injectors and intake valves clean.
The octane rating (90) is less of a concern than the lack of additives. If your car's owner's manual specifies regular unleaded (typically 87 octane), it is engineered to run perfectly on that fuel. Using a higher octane fuel like REC 90 will not increase power or fuel economy. In fact, because it's formulated for different engines, it may not burn as efficiently in your car.
The primary risk is the long-term buildup of carbon deposits on critical engine components. Without effective detergents, this can lead to reduced performance, rough idling, and decreased fuel efficiency. While a single tank in an emergency is unlikely to cause immediate damage, making it a habit is an unnecessary expense that provides no upside.
| Fuel Type | Typical Octane Rating | Ethanol Content | Primary Use | Key Consideration for Cars |
|---|
| Regular Unleaded | 87 | Up to 10% (E10) | Modern passenger vehicles | Contains mandatory detergent additives. |
| Premium Unleaded | 91-93 | Up to 10% (E10) | High-performance/turbo engines | Higher octane prevents knocking in specific engines. |
| REC 90 | 90 | 0% (Ethanol-Free) | Small engines, boats, classics | Lacks modern engine detergents; can cause deposits. |
| E85 (Flex Fuel) | 100-105 | 51-83% | Flex-Fuel Vehicles only | Can damage engines not specifically designed for it. |
Stick with the fuel grade recommended in your owner's manual. The only time REC 90 might be considered is for a classic car that has been stored for long periods, as the ethanol-free nature can be better for seals and carburetors in older engines. For any car built in the last 30 years, it's the wrong choice.
