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      05-07-2019, 03:40 PM   #208
Lieutenant Colonel

Drives: 2018 Mineral Grey M2
Join Date: Oct 2017
Location: Pennsylvania

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Originally Posted by ecitizen View Post
Thanks. What might the gas cause if the car feels like it runs fine and what's the difference with the ACN tune?
All the research I've done indicates that ACN91 is still 91 octane, and that the difference is there are more detergents in ACN91 than other USA 91. Detergents to me mean something that will break down the oil as it lubricates the cylinder walls. So my inclination is to believe the ACN91 tune has a little less boost and/or timing than the regular 91 tunes, to prevent excess heat on the engine oil which is slowly degrading due to the fuel detergents.