We just upgraded our 98 Dodge Caravan to a 2004 Nissan Quest. I have been having problem after problem with it (thankfully we bought the extra warranty) but recently it has had a knock from the engine and blowing whitish/greyish smoke. Took to dealership and they have come up with a multitude of “fixes” which has not actually corrected the problem. Now they are saying to run high octance premium fuel in it to fix everything. Was wondering if anyone else has heard of this or know if this model and year has to have high octane fuel instead of regular?