Hello,

I bought a 2003 Z06, 105K miles, about two months ago and have noticed high oil consumption.....worse than my old Subaru. I use it as a daily driver, about 600 miles/week, gas up at least twice a week due to gas gauge issue, had a fresh oil change a month ago and still putting in a quart of oil every two weeks. This morning I had to put in two quarts. I do not see blue smoke on start up or while driving, not drips/leaks on my driveway, so I'm wondering if this is something normal-ish? This being my first Corvette, and I know most are not putting on this type of mileage on theirs, but is this just something to get used to? I do some spirited driving on the back roads and highway every now and then but it usually never gets above 4000 RPMs on a normal basis. Thanks.

Robb

 

Have you checked/changed the PCV valve?

 

I'd do a Tune-up to to see where you're at.

 

First of all on the gas gauge issue, if it is what normally is experienced with this car, buy some Techron and pour it into your tank next time you fill up. Some of the lower grades of gasoline cause issues with the sensor. When I bought my '01 convertible, I immediately experienced this issue; a few treatments with Techron did the trick and if you fill the tank with the better grades of gasoline, you may never experience the issue again. If I recall correctly higher levels of sulphur in certain gasolines or gasolines without additives to combat it; impact the fuel level sending units which use silver as contacts. A very common problem at one time and our Corvettes are not the only cars to experience this issue. Techron in many if not most instances will chemically clean the silver so the gauge will read accurately.

As for your car's oil consumption; you are likely going to get a lot of opinions here, many folks will tell you their cars don't burn a drop between oil changes and you are not likely going to hear from anyone who is adding a couple of quarts between oil changes. That's human nature. The LS 1/6 engines can (not all of them do) use quite a bit of oil, particularly when you get into the higher rpms. There were a number of bulletins on oil consumption, here's a quote from one I lifted off of another forum:

"Condition
Some owners may comment on higher than expected oil consumption. When checked, the oil consumption could be in the range of 400-600 miles per quart (700-1000 km/L).
On the LS6 engine only, the technician may find oil behind the engine throttle plate and in the intake manifold.
Cause
The cause for this condition may be an interaction between the piston rings and the cylinder bore in vehicles that are operated at higher RPMs -- typically manual transmission vehicles driven in a manner where the engine is frequently or consistently operating at greater than 3200 RPM."

https://ls1tech.com/forums/generatio...nsumption.html

I happen to own a high miles (approaching 115,000) '01 manual and the '01 year is so notorious for high oil consumption that some folks would pass on that year. I have noticed higher oil consumption the harder I drive the car. Like that bulletin says, I think the manual transmission cars are going to be more prone to higher oil usage because we tend to send our tach into the higher range...because we can. I tend to need a quart of oil after 3,000 miles and I'd estimate my car uses as little as 2 and as many as 3 quarts of oil between oil changes as indicated on the DIC. So compared to my car, yes, your car is using more oil. On the other hand, your car is using half as much oil as some owners of new Z06s were reporting in 2003. Check a few things if you like, but I would not lose any sleep over it, just keep a couple of quarts of oil in the trunk.

 

Yep, try a few bottles of Techron, use the 20 oz bottle per fill up till problem goes away (hopefully it will)


As per the oil consumption. I've heard of oil consumption when it comes to tracking the C5. The high rpms seems to cause the oil consumption.
I can honestly say I can't ever remember adding oil to any of my C5s between oil changes, and I've owned five C5s.

 

Not yet.

tune up is next on the list... already had to do window regulator, water pump and radiator unexpectedly.

As to the gas gauge I don't think its a gas issue, basically at half tank or slightly under, after 40 min of driving, the needles go to "E". if driving for another 20-30 min longer the needle will go back. like something causing it to lose signal after exactly 40 minutes and I'm usually to work in 50 min. As to the oil consumption it sounds like its the nature of this beast. I'll keep some spare quarts in the car.

 

I don't race/track the car. just a daily driver. every now and then I'll redline the first three gears, and that's really far and few times, but generally never driven above 4000 RPMs.

 

That's exactly what I was experiencing with my car after I bought it. So you really should try pouring some Techron in your tank. It might take a couple of treatments. Think of tarnish on silver. The sulphur in the gas causes the sensor to send an erratic signal to your gas gauge and the gauge behaves erratically. Techron is cheap and it wont hurt to try. Its probably not the gas you are using, it will have been the gas previous owners were using. The tier 1 grades of gasoline have additives that tend to mitigate the issue.

I know it sounds like black magic- I was never a believer in fuel additives. But a lot of folks have had success with this, so trust me when I say the evidence of it working is not purely anecdotal.

As for the oil usage I think if you google LS1/6 oil consumption you will find this issue has been identified as far back as 20 years ago and you will not feel so troubled by your car. I drive my car...not quite as much as you are currently driving yours, but I've clocked 18,000 miles over the last 3 years and I think that if folks drove their cars as the car was meant to be driven (enthusiastically) they might see some oil consumption- some more than others depending on the engine and driving style. The surest way not to use any oil (or gasoline for that matter) is to park it.

 

I'll give it some more time and bottles of Techron. Have you tried any other gas treatments? Lucas Oil, Seafoam, Gumout? Or best to stick with Techron

 

Because it has worked for me, I can only vouch for Techron. If I recall correctly it seemed to work almost immediately after the first treatment, but the gauge would from time to time go haywire during my first year of ownership, so I repeated a couple more times. As for the second year of ownership, my memory is a bit hazy; maybe once? But for sure I have not had the issue in the last year...I have an unused bottle of Techron in my trunk that I bought 2 years ago.

 

I tried Techron a couple times. Didn’t really work at first until I used it on back to back tanks on a long drive. After that it cleared it up completely.

 

Your oil consumption is towards the higher end but within what is considered an acceptable level. My 03 Z06, with the exception of this year, sees 18k - 22k miles of use annually. My consumption rate of highway driving with some "fun" will yield a quart loss / 5,000 miles. I change my oil every 10k miles so I add a quart mid cycle. Oddly enough, my chevy truck with a 5.3L yields the same usage as my Vette.

Check your PCV system as someone other mentioned

 

That’s a little more than mine. I normally add one quart in between oil changes which I do at about 4000-4500 miles. It is well within the acceptable range though so I wouldn’t worry too much about it. I do drive mine hard fairly regularly but I only do maybe 7500-8500 miles a year, so I’m only adding one quart every 4-5 months.

unfortunately it kinda comes with the territory on these LS engines.