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.
On newer cars? Slightly less torque, slightly less fuel economy.
On older cars? Some pinging at high loads like towing or going up a steep incline.
On modified high performance turbocharged or supercharged cars? Catastrophic failure if pushed too hard too long.
My car isn’t modified but the manual says it will cause engine failure and override any form of factory warranty if 91+ isn’t used. Is this a hoax?
This happened to me, not bad fuel but too much boost.
Ouch, too much boost is definitely trouble. The primary goal of the performance tuning process is slowly raising boost to within the limits of the engine durability, fuel system capacity, turbocharger limits, and fuel octane. Uncontrolled over boost can crack pistons, blow rods through blocks, and generally never end well.