Just bought a 97 SVX (26K) to add to my soon to be retired 92 SVX (138K). The Toyota dealer changed the oil (only 5 quarts) and filled the tank (must have been regular). On the way home (200 miles) it shuddered and I had a cylinder misfire that tripped the engine warning light. One can of fuel system cleaner, one can of octane booster, and a new tank of premium and all is well. PREMIUM ONLY!!