Quote:
Originally Posted by tturedraider
Even though 89 is the minimum octane acceptable for your motor, if you use less than 91 then you’re motor’s electronics are going to be physically retarding the ignition so you don’t get pre-ignition, causing knock, which can damage your motor over time. That’s why you should pay the extra for premium.
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If you don't get pre-ignition then how do you get engine damage? Optimal performance is as close as you can get to pre-ignition without actual pre-ignition. In the case of C&D's test below the M5 actually got better mpg on the lower octane, although all of them are well within the range of standard error and wind direction could've made a bigger difference. But in no case does the cost of the higher octane alone make up for the difference in price.
Better performance, yes, and that's more important to me than MPG, but do you really think the average BMW owner does anything but put in the cheapest stuff and we don't see BMW's (Or MB's and Audi's) dying at 100k miles.
I suspect that 91 is probably best for my car with no tune, but my only options are 93 and 89, so I'll keep using 93. But not because I think 89 will damage my engine.
https://www.caranddriver.com/feature...dodge-charger/