Old man at the Benz dealership says he’s been driving the same car for a long time and usually only puts in 87 octane in sprinkled with 91 every few times. What problems could this cause? Do I have to put in 91?
Disclaimer: I’ve owned (paid off) the car for 6 years and do put in 91, but trying to cut costs.
According to the guys on the TV show Engine Masters it makes almost no difference these days with computer controlled ignition systems. They dyno tested regular, premium, high test, Sunoco racing fuel which is 116 octane. There was very very minor changes in torque and HP. Overall HP gain was about 10 on Sunoco racing fuel but it’s prohibitively expensive. The conclusion was if it doesn’t ping regular is fine.