Lou, I have a 2014 VW Touareg. I have used the lower grade fuel at times and feel no difference even when pulling a trailer. The fuel savings are significant and there have never been any preignition sounds. What are your thoughts on premium vs regular fuel? – Harvey
Vehicles featuring performance engines will have higher compression ratios with advanced ignition timing characteristics. When fuel is compressed, it will tend to ignite because of the heat within the combustion chamber. Octane is the rating of a fuel's resistance to ignition. Simply put, if you can keep the fuel from igniting a bit longer, it can be compressed a bit further, allowing for more power to be developed.
When you "cheat" at the pump and use regular fuel, the vehicle's knock sensors detect preignition and retard the timing well before you ever hear it. Because of its size, you may not be able to feel a difference in your Touareg, but drive an aggressive sports car and it's hard to miss.
Volkswagen will want you to use the designated fuel and I suggest during your warranty period you try to adhere. However, in most cases, no damage will occur unless you are hearing a severe "knocking" or "pinging" sound from the engine. To be honest, I don't remember the last time I repaired an engine that had clear signs of failure because of incorrect fuel use.
Pulling a trailer, especially when in extreme heat conditions or higher altitudes, would certainly be the ideal time to ensure that your vehicle is fuelled correctly.
Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing "Lou's Garage" in the subject area
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