Could that have just been the specific brand of regular that you tried that may have been substandard? I can't think of a reason why it would make a difference if you switched back and forth.
I havn't tried 87 octane regular yet, but have noticed no difference between 92 octane prem, and 89 octane mid grade. How many others have tried experimenting with different grades of gas, and with what results?
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well, we can consider it like this, consider coming from earning , oh maybe $1m a year, then downgrading to 500k a year, well it's hard to adjust, so i guess it's the same thing for cars. (just an example!) ;) especially that previous car of mine was used to premium for the first 80k, then moved to ca, downgraded to 87 from 92, had an engine ping!