C5/C6 Corvette Oil Change - Corvetteconomics 101

At first blush, changing the oil in a C5 or C6 sounds like a no-brainer, right? And yet, it is surprising how many people don't do it correctly, and only wind up with a partial oil change when doing it themselves. The reasons for this are 1) on C5s, the oil drain plug is located at the front of the oil pan rather than at the rear, and on C6s it's next to the oil filter, so jacking up the front of the car prevents all of the oil from draining and 2) the "bat wing" configuration of the C5 oil pan itself traps and holds oil, so it takes a considerable amount of time (about 10-15 minutes) for all the oil to drain completely; most folks don't give adequate drain time, so up to a quart of old oil can remain in the engine.

You can shop around for the best price on the oil and filter at different auto parts stores and/or Walmart, K-Mart, Price Club, etc. to get the best value for your dollar. And, if you purchase the 5- or 10-quart containers rather than individual quart bottles, you can save even more money.

You're the one doing the work, so you're in charge of quality control all the way through; many shops and dealerships don't let the customers in the service area, so you can't see what's being done;

You can take your time, which is important for draining as much of the old oil out of your engine as possible; I let my C5 drain for a full 15 minutes before replacing the drain plug, filter, and refilling. Time is money to dealerships and shops, so the faster they can get you and your car in and out, the more profitable each customer becomes. Rest assured, they won't let your C5/C6 drain for a quarter of an hour or more!

So there you go. And as far as equipment goes, doing a few oil changes and other routine maintenance can quickly amortize the cost of a good hydraulic trolley jack, two pair of jackstands, and any other miscellaneous tools or equipment you may acquire along the way. I always consider tools and equipment as investments that pay me dividends each and every time I use them.

One other thing I should mention here is oil capacity; be sure to consult your C5 or C6 owner's manual for engine oil capacity. I use six quarts in my '98 C5, and this brings the dipstick level up to the mid-point on the hash marks, even though the manual says 5.5 quarts (in reality, it's 6.5 quarts); remember that the filter will hold about a half-quart, so I believe that accounts for the extra oil.

Which brings us right to the point: what's the right way to change the oil in your C5 or C6? Here's how to go about it.

In the way of tools, you're going to need a 15mm box wrench or shallow socket and ratchet, a drain basin capable of holding up to seven quarts of oil, and a suitable container to hold the spent oil for transport to an environmentally correct disposal facility. (Auto Zone and many other automotive parts retailers will gladly accept your used oil for recycling or responsible ecological disposal at no charge.) You'll also need a strap oil filter wrench unless you're using a K&N oil filter, in which case you'll need a 1-inch open-end wrench or 1-inch socket and ratchet. It's also a good idea to have some paper towels and newspaper available to catch and soak up any stray oil that the drain basin doesn't catch. I'm also a big fan of nitrile gloves to keep the grimy old oil off my mitts.

If you don't have gradual-incline ramps like the Rhino units, you can elevate the front of the Corvette using a hydraulic floor jack, also known as a trolley jack. Bear in mind, however, that the bodies of C5s and C6s curl and wrap around the hydro-formed framerails, so it's easy to dig into and crack the body plastic on the underside of the car. The framerails, however, have oblong/oval shaped openings at the front and rear on both sides of the frame, and these openings are intended to be used as jacking points. You can purchase a jack insert that will replace the stock lifting platen of your trolley jack, and this insert will fit into the C5/C6 openings like a hand in a glove, thus permitting you to lift the Corvette properly without causing any damage. Another option is to purchase a set of four aluminum lifting pads that fit these openings and give you a solid platform to jack from. A third alternative is to purchase a set of four plastic lifting plates that serve the same purpose as the aluminum pads. The jack insert, the lifting pads, and the lifting plates are all available from Mid America Motorworks as well.

Regardless of which of these methods and mechanisms you use to elevate your C5, you're going to need a pair (or two pair if you don't use ramps) of jackstands to support the vehicle safely when it is off the ground. It's time for me to get up on the soapbox now, so bear with me while I do a little preaching here. Never, ever, get under your C5 or C6 (or any car) for any reason without supporting it properly. Jackstands are inexpensive insurance against injury to you and your beloved Corvette, so don't be foolish to work on your elevated vehicle without having them in place. Nothing can ruin your day like having your Corvette come crashing down on top of you, so don't be penny wise and dollar foolish when it comes to equipment. Enough said on safety, so let's move on.

Before removing the drain plug, however, open the hood and remove the oil filler cap and pull the dipstick up a bit so that it's not fully seated. This helps to relieve pressure and enables the oil to drain a bit faster. I also suggest that the engine oil be warm when doing the oil change; warm oil is thinner and flows more quickly than cold oil.

If you use K&N Oil Filters, like I do, here's a little tip to help keep things neater. The K&N filters have a 1-inch nut welded to the bottom of the filter, which makes for easy removal using a 1-inch open-end wrench. I loosen the filter about 1/2 turn, then slide a plastic bag over the filter and unscrew it the rest of the way by hand. As the filter comes off, the plastic bag catches it and the resultant dripping oil, thus preventing it from getting on the garage floor or driveway surface. Ostensibly, this trick will work with other brands of filters as well, once they're loose enough to be spun off by hand.

GM specifies that you must use oil that meets or exceeds General Motors standard GM4718M (synthetic 5W30) in order to maintain your new factory warranty. However, not all synthetic oils meet this standard. So be sure to purchase oil that meets or exceeds this standard. GM uses Mobil 1 5W30 as the factory fill on the assembly line at Bowling Green. I use Royal Purple 5W30 synthetic, but that's my personal preference. You can use any brand you wish as long as it meets or exceeds the GM standard.

At this point, most folks lower the car and proceed to fill the motor with new oil, but I feel this is a bit premature. The way I do it is to first level the car, then pour in 6 quarts of new oil, replace the filler cap, and push the dipstick all the way home. I generally give it about 5 minutes to allow the new oil to fill the pan. (CAUTION: Make sure the C5 or C6 is in park if it's an automatic, or in neutral if it's a stick.) Start the engine and let it run for a few minutes, shut it off and check for any leakage around the filter and drain plug; if there are any problems, now's the time to take corrective measures while the car is still elevated. If everything checks out OK, you can reverse the methods you used to elevate the car to get it back on the ground again.

This is easy to do, and resetting the indicator is necessary so that you'll know when your next oil change is due. For a C5, turn the ignition switch to "on," but do not start the engine (however, this can be done with the engine running in a C6). Press the "trip" button on the DIC so that it cycles through until it displays "oil life" percentage remaining. Press and hold the "reset" button for two seconds. "OIL LIFE REMAIN 100%" should appear on the display. You can shut off the ignition switch or, better yet, start her up and take her out for a spin.

Tools Required: low-profile trolley jack, four sturdy jackstands, bubble level, droplight, 15mm wrench or socket w/ ratchet, 5w30 synthetic oil, filter, oil drain pan; optional: gradual-incline Rhino Ramps, FilterMag, magnetic oil pan plug, 1-inch wrench, creeper or mat, latex or nitrile gloves
Time Required: about 1 hour
Parts Source: auto parts store