developtrust wrote:
I went to Cabo san lucas a couple of years ago driving my Mercedes which
recommended Premium fuel. I noticed that the best Mexican fuel was our
lowest grade. Using it I  noticed no pinging or problems whatsoever and have
used lowest grade fuel ever since.
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If your vehicle is about 1985 or newer, it may have a knock sensor which
will automatically retard the timing when it senses knock.  It happens so
fast you will not hear it.  You may notice a slight reduction in power.
North American vanagons with 9:1 CR never needed knock sensors.  1985 and
newer VW GTIs and 16 valves got it.  Basically any VW model with 10:1 CR.

Gary
Calgary