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.
Do you like gambling? Detonation is the term for uncontrolled fuel ignition, and is the possible result of running lower octane than required. The car can somewhat mitigate the issue by trying to adjust the spark timing, but if you’re lucky and the fuel ignites spontaneously in multiple locations you can get pressure spikes in the 10’s of thousands of psi. If they happen in the right place little pieces of piston / cylinder wall start getting blown off, then maybe they land somewhere they shouldn’t. Just buy the correct gas.