If you don't drive enough to boil the water out of the oil, it will show up in the valve cover, top of the dip stick, etc. I don't use 91 octane in anything I own, all running on 87 octane.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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