Duke oil question??

**Duke W.** · August 27, 2009, 01:14 AM

Re: Duke oil question??

Since I do not own a late model Corvette, I have no personal experience, however, all of my cars, which are vintage or "older" show virtually no signs of oil darkening until nearly a thousand miles, and I am even starting to let the annual oil change go to bienniel status because they accumulate so few miles per year, and the oil looks like new.

The above should be the case if the rings have a good seal, the PCV system is in good working order, and you don't drive mostly short trips of only a few miles.

Be sure you follow GM's requirement for warranty maintenance, which AFAIK requires an annual oil change regardless of mileage or oil monitor indication. If you have a dry sump model I believe there is also a pan drain in addition to the remote sump drain.

Beyond this you should seek advise from other late model Corvette owners and, perhaps, a service advisor at your dealer.

Duke

**Chuck S.** · August 27, 2009, 01:35 AM

Re: Duke oil question??

Originally posted by Tom Stanton (41491)

Duke I have an 08 vette. I have changed the oil and filter twice and have just over 6k on it. I use Mobil 1 and AC oil filter. Shortly after the oil change the oil looks very dirty. The mileage is almost all highway mileage. What makes the oil look so dirty? I have 81% showing on my DIC and the oil looks filthy now. Is this normal? My first experience with a new vette and Mobil 1. Please advise. Tom Stanton#41491

Tom, "appearance" of the oil has little to do with the actual oil life remaining, or, whether you need a change.

GM's oil life monitor programming is designed to wring the most out of an oil change based on extensive GM test experience. This benefits the environment and reduces the cost of maintaining a GM car. Some CF owners were running the oil life monitor down to 0%, and were probably getting 10K miles between changes; others were changing at 50% life.

Most of us don't put enough miles on a Corvette to change by the oil life monitor and end up changing at least annually as recommended. If I were going to use the oil life monitor, I would probably not run it down to 0% percent oil life even though that really cuts your maintenance cost. Personally, I would HAVE to change my Vette's oil between 5K and 7.5K miles or whatever oil life monitor reading that represents.

P. S. My experience with my 2006 was that the first oil change was very black after only 1100 miles, and the second change at one year was not as black. The total miles after a year were probably around 3500.

**Jim T.** · August 27, 2009, 09:35 AM

Re: Duke oil question??

Tom my 96LT4 bought new has only had yearly oil changes as per miles driven and recommended in the owners manual. It came with MOBIL1 oil and have continued to use MOBIL1 oil.
Before I do the yearly oil change it appears pretty clean on the dipstick.
After an oil change and driven when checking the oil I have to do it outside in the sunlight to determine where the oil level is on the dipstick because it is so clean. It stays like this for some time.
When bought new at Kerbecks I drove from NJ to west TN only stopping for food and gas. Oil was still clean.
My 85 aslo stays pretty clean between oil changes.

**Patrick H.** · August 27, 2009, 10:16 AM

Re: Duke oil question??

Chuck,

Much of the results of GM's oil monitor testing is available on the 'net if you search for it. In the end, it is very accurate, and they allow for a 500(ish) mile window after the 0% level. I have no problems or reservations following it.

I use the GM oil monitor on my truck and my minivan for every change, and essentially never change it prior to that. The truck will probably get changed a bit before 0 this fall as I'm taking a trip to western Montana and back which will bring me over the 0% mark.

As with others, the 08 Corvette doesn't get enough yearly miles to hit the 0 mark in a year.

Patrick

**Tom S.** · August 27, 2009, 01:34 PM

Re: Duke oil question??

My 88 stayed very clean. I only drove it 2k in five years but changed it yearly. It was standard oil in that. The 08 gets dirty looking after just a couple hundred miles and its synthetic. I am driving it to the museum next week so I will change it after I get back. That will be 1 year and about 4k miles since its last change.I just don't understand why the dirty look so fast with synthetic? I have the same thing with my wifes HHR, which is going back to standard oil.

**Chuck S.** · August 27, 2009, 03:48 PM

Re: Duke oil question??

Originally posted by Tom Stanton (41491)

My 88 stayed very clean. I only drove it 2k in five years but changed it yearly. It was standard oil in that. The 08 gets dirty looking after just a couple hundred miles and its synthetic. I am driving it to the museum next week so I will change it after I get back. That will be 1 year and about 4k miles since its last change.I just don't understand why the dirty look so fast with synthetic? I have the same thing with my wifes HHR, which is going back to standard oil.

I'm thinking this effect, i.e. dark oil after only a few hundred miles in new Corvettes, has less to do with the oil being synthetic than it does with the assembly and break-in of modern engines. This topic was discussed a couple of years ago on CF, but I don't think anyone came up with a definitive answer; only that it happens.

My first "late model" Corvette was an 87 convertible that I acquired with nearly 50K miles on the clock. It had been meticulously maintained with regular changes of Mobil One. I continued the maintenance program, and the oil never appeared dark like the first changes on my later 2006 (bought new)...it was always clear amber.

To satisfy my curiosity just now, I went to the garage to check the oil "appearance" and the oil life monitor of my 2006. The oil was primarily clear amber with evidence of light use, and the oil life monitor indicates 71% oil life remaining. This oil has about 1000 miles since it was changed in January (it's been a busy year...no time for Corvette fun). Total mileage is about 6300.

I believe your oil color will begin to clean up after another change or two. In any event, your oil and your engine are fine; quit watching the color (you can't tell anything from that anyway) and stop worrying.

**Chuck S.** · August 27, 2009, 04:13 PM

Re: Duke oil question??

Originally posted by Patrick Hulst (16386)

...Much of the results of GM's oil monitor testing is available on the 'net if you search for it. In the end, it is very accurate, and they allow for a 500(ish) mile window after the 0% level. I have no problems or reservations following it...

Yeah, yeah, I know...As a former maintenance engineer, my brain KNOWS that maintenance expense can be reduced to the absolute minimum using experience and science. The theory worked great for Exxon's pumps and turbines.

On the other hand, when it comes to extended maintenance intervals for my VETTE, I'm somewhat like ole Indiana Jones in Raiders of The Lost Ark(?)...He has to step out into a bottomless chasm to find an invisible bridge to the Holy Grail. Fortunately, it's not a decision that I have to make for the Corvette (annual changes don'cha know).

Now, my wife's Malibu...I'm using the oil life monitor, but changing with about 30% oil life remaining. And, I use Valvoline conventional 5W-30...None of that fancy synthetic oil for work horses.

**Tom S.** · August 27, 2009, 06:08 PM

Re: Duke oil question??

Thanks for all the replys. I am going to change the oil when I return from Bowling Green. Maybe it will start to clear up then. I am also thinking about using the UPF48 filter rather than the standard PF48. Thanks again. Tom

**Terry M.** · August 27, 2009, 07:53 PM

Re: Duke oil question??

Last Fall I changed the oil (for the second time) at 8000 miles. It now has another 10K miles on it and the oil life says there is 30% left. Over the winter the oil life never changed, and I didn't start the car. Most of the driving this year has been nice long highway trips like the Road Tour to California. That is easy on the oil.

The fresh oil (Mobil 1) is a light camel color, but it soon ages to a dark chocolate brown. I don't think it is dirty. I suspect it is heat related. These new cars run HOT. Not the coolant temperature, but open the hood after a thirty or more mile drive and the heat will push you back. I think the oil is discoloring from the heat.

BTW: Over on BITOG they keep insisting the color of the oil means nothing.

Duke oil question??

Duke oil question??

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