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C5/C6 Corvette Oil Change - Corvetteconomics 101

A C5/C6 Oil Change The Right Way

Tom Benford Apr 12, 2010
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I'm feeling the economic pinch big-time these days (like just about everyone else I know) and I am tightening my belt, trying to make every dollar stretch as far as possible. In addition to cutting back on frivolous, whimsical, and non-essential spending, I'm also doing a lot of things around the house and garage myself rather than farming them out, and you can, too. One of the ways to save yourself some significant bucks is to do routine maintenance chores on your Corvette yourself, like flushing the cooling system, rotating the tires (if applicable) and changing your own oil.

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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.

There are several reasons to change your own oil, such as: You can use the brand of oil and filter you prefer, rather than being forced to use what the dealership or service shop is pushing that day.

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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!

There's a lot of satisfaction in doing your own work, and most people who do so find that they enjoy their Corvettes even more; it's almost a Zen thing wherein you "become one with the machine."

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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.

A question I've been asked frequently over the years is, "How often should I change the oil in my C5/C6?" There are many ways to answer this question, but I suspect that no single answer will satiate everyone. Many folks go with the traditional "change the oil and filter every 3,000 miles whether it needs it or not" philosophy, while other folks wait for the DIC (Driver Information Center) to tell them it's time for an oil change. If you abide by what the DIC tells you, it's a good idea to change the oil and filter between 25 and 10 percent, rather than letting it go to 5 percent or less oil life remaining. The reason for this is that GM's algorithm for the DIC to determine how fast the oil life reading changes from 100 to 0 percent, but, while pretty sophisticated, doesn't account for dust and other contaminants that may steal additional lubricity from the oil. So, to be on the safe side, don't push the oil life envelope. Several manufacturers of synthetic oils make claims (some hard to believe) that you can go 5,000, 10,000, 20,000 miles, or even more before changing the oil. Well, not my C5. I change my oil and filter at 5,000 miles. Regardless of what brand of oil you use, never let your oil go past 10,000 miles before changing it or you're really asking for trouble.

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Mobil-1 is the factory-fill oil for Corvettes, although you can use any 100 percent 5w30 synthetic oil you like. My preference is Royal Purple, which I've used in this car for several years now. I am also a fan of K&N oil filters (I especially like the built-in nub on the bottom of the filter which makes removing and tightening a breeze), but this, too, is a matter of personal preference.

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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.

The first thing you'll have to address is elevating your C5 or C6 and supporting it while it's off the ground. A pair of gradual-incline ramps such as the Rhino Ramps offered by Mid America Motorworks is ideal since they're designed specifically for low ground-clearance cars like C5/C6 Corvettes. These ramps are made of strong, lightweight plastic and the bottom surface is waffled to distribute the weight evenly across the entire contact surface of the ramp. What this means, simply, is that they won't dig into the tarmac of your driveway or scratch up your garage floor the way pressed-steel ramps do.

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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.

Or, you can also use your trolley jack to lift the entire rear end of the C5 off the ground by placing it under the transaxle crossmember. If you go this route, you'll need a trolley jack that has a very low profile, and I strongly suggest using a padded jacking platform such as the one offered by The Eastwood Company. This padded platform simply drops in place on the trolley jack just like the stock lifting platform that came with the jack.

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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.

As I mentioned earlier, the C5 oil drain plug is at the front of the oil pan, so the nose of the car should be lower than the rear in order for the oil to drain forward. Having the rear of the C5 elevated about 2-4 inches higher than the rear will do nicely to help evacuate the old oil. On the C6, the drain plug is next to the oil filter, so the vehicle should be level for changing the oil, rather than having the rear slightly elevated a la C5.

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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.

Next, it's time to position the drain pan underneath and slightly forward of the drain plug. Use your 15mm box wrench or socket and ratchet to loosen and, ultimately, remove the drain plug. Give it at least 15 minutes for the oil to drain. When the flow has slowed down to a thin trickle (or better yet, intermittent drops), you can replace the drain plug; 15 lb-ft is the factory torque spec. I use the "feel" method, however. That is, I tighten it until it feels tight enough to me. Be sure not to over-tighten the plug-it's a bear to remove at the factory spec, so it may well be impossible to get it out without ruining it if you go too tight. Now you're ready to move the drain pan under the oil filter and remove it.

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A word about magnetic drain plugs is in order here. For about $5.00 you can replace the stock drain plug with an aftermarket magnetic drain plug available from Mid America Motorworks and other suppliers. In the overall scheme of things, $5 is very cheap insurance to help safeguard your engine from possible damage that can be caused by stray, minute steel or iron particles that may be suspended in your oil circulatory system. At the very least, five bucks will buy you a lot of peace of mind.

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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.

And, if you really want to get some extra engine protection, you might consider investing in an oil filter magnet for a few dollars more. Mid America Motorworks has a nice disc-shaped unit that grabs onto the bottom of an AC/Delco filter or other smooth-bottomed filter and traps and holds any stray ferrous particles that enter the filter from the lubrication stream. This disc-shaped filter magnet doesn't work with the K&N filters due to the 1-inch removal nut abutment I mentioned earlier, so I use a cylindrical FilterMag wrap-around oil filter magnet available from

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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.

OK, now it's time to install a new filter and refill the crankcase with oil. The General calls for an AC/Delco UPF44 or equivalent filter, and, once again, the brand you use is strictly a matter of personal preference as long as it meets or exceeds the factory spec. Be sure to coat the rubber gasket of the filter with some new oil before installing it. This will ensure a tight fit between the filter and the engine block and prevent any leaks. The factory spec for the filter is to tighten it using 22 lb-ft with a torque wrench. Again, I use the "feel" method here, too. I just hand-tighten the filter about one full turn after the gasket makes contact until it "feels" tight enough, and I've never had any leakage problems using this method.

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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.

Open the hood and check the oil level with the car sitting on level ground (I use a small bubble level resting on the door sill plate to check for levelness); the oil will probably be a little low, which is normal. Add an additional 1/2 quart of oil if required, start it up and let it run for a few minutes longer, then shut it off and check the oil level again. It should be right on the money now. If it is, the next task is to reset the "oil life" indicator on the DIC.

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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.

Take the used oil to Auto Zone, Pep Boys, or just about any other national auto parts outlet who will accept it for ecologically-responsible disposal/recycling at no charge. That's all there is to it. So you've saved yourself some money and the job is done right. So why not treat yourself and the family to a pizza with the saved cash? I told you it wasn't a difficult job, didn't I?

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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


Surprise, AZ 85374
Mid America Motorworks
Effingham, IL
The Eastwood Company



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