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Can a 1999 SLS be modified to run on 87 octane?

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Hi all. Its been a while since I've been on this site. I have a quick question, and hopefully, its an easy one to answer. I have a 1999 SLS with 82K miles. 99's are to be run with Premium grade gasoline, which is getting pretty expensive. I know the 2000's were changed so they could run on Regular. Can I modify my 99 to run on Regular? Anyone done this? How would it be accomplished? I'm curious so feel free to reply.

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You can use it, your NS has a knock sensor and the PCM monitors it, if your engine knocks, the PCM will RETARD timing to stop the knocking... You can/may loose performance as a result, it might feel like a pig.. I run the middle grade all the time but I knock with regular in the heat and traffic

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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