is 93 octane acceptable/optimal for a 1987 328 ??
You have to clarify what version 328 (euro or US), and whether you are talking about 93 AKI (the octane rating used on the pumps in the US) or 93 RON. The manufacturer's specs in the 328 OMs are: US 328 = 95 RON minimum = about 90 AKI minimum euro 328 = 98 RON minimum = about 93 AKI minimum 93 AKI would be "acceptable" for a US 328, but you would be overpaying for something that you don't need (and might reduce power a smidge).
While on the subject, how about the best gas for a carbed US spec 308? I heard that using anything other than 87 octane is a waste bc the engine cant take advantage of it.
Certainly true for a '78-'79 US version 308 that only has a 91 RON minimum fuel spec (about 86 AKI minimum). The '73-'77 US 308 might have a higher spec (I've no data), but it was also from a time when available fuel octane was generally higher so the manufacturers weren't so fussy about trying to spec the absolute minimum octane rating needed and could error on the high side without impacting the consumer much. Also, the octane rating on the US gas pump is the minimum guaranteed AKI value -- not the exact AKI value -- so all "87 octane" is not necessarily equal (and people's experiences may vary).
I saw this while reading a little about fuels from a Toyota manual. I was not aware of seasonal changes. Has this been discussed before? Screen dump from following link http://www.autoshop101.com/forms/h57.pdf Image Unavailable, Please Login
The winter/summer volatility change does not change the octane rating of the fuel delivered at the pump. So it does not need to be considered from the aspect of octane rating.
