strong>Dear Doctor: I recently purchased a 2014 Volkswagen Tiguan. It has an intercooled turbocharged four-cylinder that requires premium fuel. The dealer told me to put high octane fuel in it (90-91 octane). Can I use mid-octane 88-89 in lieu of the higher priced fuel? Ed
strong>Dear Ed: Others may disagree, but it is my opinion to not recommend the use of the mid-grade gasoline for this vehicle. You have purchased a vehicle that has a small four-cylinder engine -- which has plenty of power due to the inlet pressure from the turbocharger. Premium gasoline burns hotter, slower, cleaner, and has a higher quality additive package that leaves less carbon deposits on the valves. This can actually save you money over time. The difference in gas cost is about the price of a large coffee each week -- not to mention the power difference you will experience from the higher octane fuel.
strong>Dear Doctor: I have a 2002 Mercury Grand Marquis. The "check engine" light has indicated the coil on the #5 injector is bad, which also blew the 20-amp fuse for the injectors. We replaced the coil and fuse, and then the replacement coil and fuse also blew. The alternator is good. Any suggestions? Lou
strong>Dear Lou: The first step is to check the wires to the injectors for wires that might be frayed. The next step is to check the resistance in each injector. Have a technician check on the Identifix web site for any history on this problem. Then look on the Alldata web site for the wiring diagram.
strong>Dear Doctor: I have a 2010 Acura MDX with 55,000 miles. The steering is stiff at very low speeds or when trying to turn out of park. It's not the powering steering pump. But I read on a forum that this could be a power steering sensor. What could this issue be? Peyton
strong>Dear Peyton: This is a common complaint with many of these vehicles. I've seen faulty power steering pumps -- as well as faulty o-ring seals on the return line by the pump -- cause this issue. A good place to start is with a line pressure test. Always use Acura steering fluid only.
strong>Dear Doctor: I read your recommendation to a reader regarding his question on reverting back to conventional oil from synthetic and whether it would cause harm. I've always understood that going from conventional oil to synthetic would possibly leak. Can you clarify further? Enjoy your column very much. Gerard.
strong>Dear Gerard: Oil leaks were very common in the old days with older car engines -- the gaskets and tolerances were very poor. Yes, oil leaking was a problem back then, and in fact the use of full-synthetic oil would increase leaking. However, today everything has improved with oil, engine design, and engine sealing. Today, a lot of manufacturers recommend the use of full-synthetic oil. You can switch over to conventional oil, as long as the manufacturer does not specify full-synthetic oil only.
strong>Dear Doctor: My 2003 Cadillac DeVille has a vibration at speeds over 60 mph. I get the tires balanced and rotated every 4,000 miles. What should I do? Ellen
strong>Dear Ellen: The vibration problem on your DeVille sounds like a tire and/or rim balance problem. I think you're throwing money away having your tires balanced and rotated every 4,000 miles.
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