5th O2 Sensor this year!!

[blue2000s]

Originally Posted by bmwm750

I can't possibly see what your mechanic claims 87 octane would do for your motor, aside from cause problems. While there are differences in winter blended fuels (in those parts of the country where it does get cold), ad that could hypothetically cause issues with certain motors (never heard of this directly, but it could be plausible), running a lower octane fuel to "clean" an engine is ridiculous. All that would do is force the engine to run greatly reduced timing to control knock, limiting performance, and making the DME re-learn how to operate on the proper fuel once its given it, and may or may not cause serious damage in the interim.

What may contribute to your 02 sensor issues during the winter is the longer time it takes things to heat up from a cold start, which would cause increased deposits to form on the sensors.

I'd also consider looking for a new mechanic.

Patrick

The sensors are self-heating. They wouldn't have this problem.