In the course of diagnosing a rattle (was a worn out flex pipe) my car made a pinging sound when we had on rack to diagnose flex pipe rattle. My mechanic said (not sure if I understood correctly) that the 3.7 pistons are flat which can lead to preignition causing that pinging sound. Recommended I use 91 vs 87 octane. Book says 87 or higher...does that make any sense? Gas mileage is good and never heard that pinging before. Thanks for all the help and info you all share.
Last edited: