Keep in mind that in addition to lubricating an engine's moving parts, motor oils are designed to carry combustion by-products away from the pistons and cylinders. Oil is formulated to collect and deal with dirt and dust that enter the engine through the intake, and condensation that forms when the engine heats up and then cools off. It must also handle any coolant or fuel that may get in the crankcase, as well as any acids that may form from the reaction between water and other contaminants.
When trying to determining the rate at which contamination and additive depletion occur, it's important 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 a meticulously tuned car, most newer Corvettes could go 7,500 to 10,000 miles between oil changes. But in the world in which most of us live, I think a 3,000-to-3,500-mile interval is prudent. Remember: changing your oil more often than needed will not hurt an engine, and an oil-related engine failure will cost you a lot more than five quarts of synthetic and a filter.
If you do choose an oil-change interval of 10,000 miles, remember that while the Delco PF 44 oil filter uses an excellent "Duragard" synthetic filter media, it is of a rather small capacity. For this reason, it is recommended that you change the filter every 3,000 to 3,500 miles.
I have an '00 Corvette, and it seems like it's using about a half a quart of oil between changes. There's no evidence of an oil leak on the garage floor. I even took the car to my local dealer to find out if my engine had an internal problem and was burning oil. It charged me $90 and told me It couldn't find a problem. (That dealer went out of business about two weeks after it worked on my car.) Was it just giving me a quick line to get rid of me, or is it normal for a Corvette to use some oil?
Via the Internet
All engines-including those used in Corvettes-require oil to lubricate and protect internal moving parts such as cylinder walls, pistons, and rings from wear. When the piston moves up and down on the cylinder wall, it leaves a thin film of oil. During the power stroke, a part of this oil layer is consumed in the combustion process. As a result, some oil consumption should be considered normal in any engine. (The accepted rate of oil consumption for Corvettes from '90 to '09 is approximately one quart every 2,000 miles.)
We recently received a question about a show car that was never driven more than a few miles at a time. This car would actually show the oil level to be over-full, even when the correct amount of oil was in the crankcase. This phenomenon can be caused by fuel and condensation generated during cold engine operation, and the engine's inability to generate enough heat to evaporate these contaminates.
Rest assured that if there's no oil on the floor, your Corvette is not leaking. Just keep an eye on that oil level and be sure it stays topped off.
I own an '08 Corvette, and the convertible top is separating near the windshield. Is this a common problem on these models, and is there a way to fix it permanently?
Via the Internet
Fortunately, there is a Customer Satisfaction Campaign (Bulletin # 08312) that addresses your problem. It seems that fabric on the convertible top can begin to separate from its retaining bracket near the windshield at vehicle speeds of approximately 100 mph or faster. (Don't worry; we won't tell.)
The repair includes the installation of a new retainer bracket and covers the following models:
•'08 Corvettes from VIN 85117774 through 86135284
•'09 Corvettes from VIN 95100002 through 95112678
Contact your dealer and confirm that your Vette is covered by the campaign. The program will be in effect until May 31, 2010.
Hope this helps, Ralph, and watch out for radar.
Got a question for our Tech Corner expert? Just jot it down on a paper towel or a lightly soiled shop rag and send it to us at VETTE Magazine, Attn: Tech Corner, 9036 Brittany Way, Tampa, FL 33619. Alternatively, you can submit your question via the Web, by emailing it to us at firstname.lastname@example.org. Be sure to put "Tech Corner" in the subject line.