Question: It seems like there are a lot of conflicting opinions on when to change the oil in a Corvette. I've been changing the oil in my '09 convertible every 3,000 miles; is this too often? Should I just follow the car computer? Do I need to change the filter on every oil change?
David
Via the Internet
Answer: This seems like it should be a simple question to answer, but sometimes things aren't as simple as they seem. Let's start by covering the basics. You need to change your oil on a regular basis, because all motor oils break down over time. Once that breakdown has occurred, the oil loses its ability to protect your engine.
Besides lubricating an engine's moving parts, motor oils are designed to carry combustion byproducts away from the pistons and cylinders. Oil is also formulated to collect dirt and dust that enter the engine through the intake and condensation that forms due to heat cycling. Engine oil must also contend with any coolant or fuel that gets in the crankcase, as well as any acids that may form from the reaction between water and other contaminants.
This all means that the more you drive your car, the more the oil will become contaminated. Oil additives are used up over time, and the oil itself can oxidize or thicken, preventing it from doing its job. While knowing this may make you want to change your oil every time you start your engine, today's oils are remarkably resilient and long-lasting. That said, how often you change your oil should depend on several factors.
To determine the rate at which contamination and additive depletion occurs, we need to consider climate, driving conditions, fuel-injection or carburetion adjustments, and the general mechanical condition of the engine. In a perfect, climate-controlled world, with ideal driving conditions and an optimally tuned car, you could easily go 7,000 to 10,000 miles between oil changes. But since none of our vehicles operate under such conditions, I think you're doing the right thing by changing your oil every 3,000 to 3,500 miles.
In some circumstances you'll need to change your oil more frequently than you normally would. These include a misfiring engine or extremely cold operating conditions, which can cause raw fuel to be introduced into the crankcase. Driving the vehicle hard-as you would at a road-course event or during a night at the dragstrip-will also require more-frequent oil changes. It's also a good idea to change the oil if you're getting ready to store your Corvette for the winter. This will remove any contamination and acids from the crankcase, so no bearing damage can occur during storage.
Every time you change your oil, you should change the oil filter as well. Most areas have oil-recycling centers that will take your used oil and filters. You can also check with your local parts store to see if they have a similar disposal program. Finally, always check your owner's manual for the type of oil you should use and the frequency with which you change it.
Question: I have an '04 Z06 with an in-tank fuel-pump/fuel-filter assembly. How often does the filter need changing?
Mike in Tennessee
Answer: We've had several questions on this topic, Mike. Fuel filters located inside a fuel-pump module are generally considered lifetime units and should only be replaced if the pump fails. In fact, you could create a lot of problems by trying to replace the filter as part of your regular maintenance regime. Since there have been very few instances of in-tank filters becoming clogged, the old maxim of "If ain't broke, don't fix it" definitely applies in this case.
Question: This isn't really a tech question, but here goes. I was at a local Corvette show, and a few of the guys I know were talking about the first Corvette. One of them stated that it used an American flag for its emblem. Is this true, and how did the Corvette emblem originate?
Lance from Florida