Will ULP 91 damage your high-octane fuel car?

Many of our members have been in a situation where they have put unleaded fuel in a diesel car and visa-versa, and as we all know, it can prove to be an expensive mistake.

However, what exactly happens if you put 91 octane ULP in a vehicle specified for high-octane fuel?

We spoke to RACQ’s Principal Technical Researcher Russell Manning to get a definitive answer for our members.


“Most cars sold in Australia since 1986 are designed to run on 91 RON octane fuel but an increasing number require 95 or 98 octane fuel,” Mr Manning said.

“Some vehicles specified for high-octane fuels only, will still operate satisfactorily but the driver will experience reduced power and fuel economy.

“But some, particularly high performance models, could experience potentially expensive engine damage.

“There really is no single answer to this question as it depends a lot on the engine’s design, so we advise all motorists to check their owner’s manual or contact their dealership before taking the risk of using a fuel other than that specified for the vehicle.

“If you find the fuel isn’t suitable, don’t start the car, and call us on 13 1111 at the earliest opportunity.”

For more information visit RACQ.com.