# 7,400 miles and NINE months.



## GTOtbird (Mar 4, 2006)

Before the "Service Oil" message came on yesterday. This is good news as the Mobil 1 oil is expensive. I've always said that 3,000 is too short for most drivers. I used to change oil about 4-5,000 miles and never had any problems. I really like the GM monitoring system to cut down on the "wasteful use of a non-renewable, natural Resource."

Question: What mileage are you typically getting between the Service oil messages?


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## Gregscalade (Dec 6, 2006)

I've loved all my cars and their engines. I don't care what anybody, or any computer tell me. I change at 3k.

Not intended as a flame on you...just how I do it.


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## 242379 (Dec 3, 2006)

No flame here but... after the 500 mile break in I changed my oil. I plan to change it again in approx 2500 miles, then every 3000 miles.
The waste oil where I work is recycledarty: 
I've seen what lack of oil changes can do, but not to my LS2:cool


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## Gregscalade (Dec 6, 2006)

Exactly.

I also recommend changing the trans fluid after the 1st 1500 or 3000 too.


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## BigNick (Jan 7, 2005)

Changed the oil at 750 and 3000, and will again at 6000. 49.5 weeks of ownership and I'm still not at 6000.

Driving only the Buick for winter since early December, lost to a Mini Cooper S convertible today.... ugh.


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## ACR (Nov 28, 2006)

GTOtbird said:


> Before the "Service Oil" message came on yesterday. This is good news as the Mobil 1 oil is expensive. I've always said that 3,000 is too short for most drivers. I used to change oil about 4-5,000 miles and never had any problems. I really like the GM monitoring system to cut down on the "wasteful use of a non-renewable, natural Resource."
> 
> Question: What mileage are you typically getting between the Service oil messages?


Mobil 1, is 100% synthetic, not a natural resource, but I get your point. For some of us, changing oil is like taken a shower, ya know, you want to be extra clean. Just can't help it, fresh oil in her every 3K.


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## raven1124 (Sep 23, 2005)

Same here. Amsoil every 3k.


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## oldsow (Aug 6, 2006)

changed oil after first 1000 miles to royal purple, after 1500 put in the new gmm ripshifter street, and same time put in the royal purple synchromax. will change oil at 3000 mile intervals. last weekend done all new pedders rear suspension and Harrop, change rear end fluid to amsoil 75w 140. 
engine purrs , quiet tranny and rear end is very smooth.
Love my Goat, nuttin but the best for her.


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## fergyflyer (Apr 18, 2005)

Well I guess I'm in the minority. I don't change mine at every 3,000 miles. I think it's an absolute waste. I've gotten over 300,000 miles on gasoline engines with 5-6,000 mile oil changes on dino oil. I've never had an oil related problem or failure. 

The C6 gets it's oil changed every 6 months, which is working out to about every 2500 miles. Time is much more important in regards to oil life than mileage. 

GM is a very cheap company. They warranty engines to 100,000 miles. Do you think they would do that if the oil monitoring system didn't work? Do you think they would spend the money to put an oil life monitor on the car ? 

I've seen tests where they took taxi cabs and measured weights of pistons and rings. They measure the bores in the block. Then they ran 100,000 miles and tore the engines down. Remember, NYC taxi cabs get some pretty tough use. What they found was no difference between 3000 and 6000 mile oil changes. Between 6000 and 9000 there was almost no difference. Between 6 and 12000 mile there was slight differences, but not enough to warrant changing the oil more frequently. The also found that there was no difference between brands. The only cars that showed difference between synthetic and dino oil were the 12,000 mile and 9000 mile cars. The synthetic engines at 12000 mile intervals looked like 3,000 mile dino engines. In this period, only one engine failed and it was a 3,000 or a 6,000 mile dino oil engine. 

I've seen other tests indicating that changing your oil more frequently than 2000 miles causes more engine damage. Even if you refill the filter, which they are definately not doing at the quik lube or the dealer, you have a period of time that the engine doesn't have any oil flowing to the top side. 

BMW has an oil life monitor that follows the same principles that GM's does. If you take your car into a BMW dealer and tell them you want your oil changed at 3,000 miles, the dealer is not allowed to. The dealer tells the customer that the BMW is a premium engineered vehicle with full synthetic oil, there is no need to change it more frequently than once per year or when the oil life monitor triggers, whichever is sooner. If the customer insists they do a courtesy check, which involves taking a small smple of oil and testing the quality of the oil. They then tell the customer that the oil is at xx percent of oil life and there is no need to change it. 

These are scientificly tested facts. If you prefer to change your oil sooner than is needed, that's up to you. It's kinda like people that have a car designed to run on 87 octane putting a higher octane into it. You aren't being nicer to the car, you are spending money for something that gets you a peace of mind benefit only.


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## Gregscalade (Dec 6, 2006)

To settle this great debate, I will convert my car to a 2-stroke, and run premix.

:rofl:


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## Sabraxas (Oct 29, 2006)

so I have a question for you Fergyflyer ( just out of honest curiousity ). Why does it say 'Premium gasoline recommended' for my GTO if I can run regular and get the same affects? Is there some performance difference or what? Thanks for any response.


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## Gregscalade (Dec 6, 2006)

87 octane will yield slightly worse acceleration/performance, and you'll probably get some knock.


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## Guest (Dec 22, 2006)

*oil change*

do your oil changes between 2500 and 3500 miles.. yes you can go a lot longer with full synthetic oil, but why take a chance,,, oil changes are cheap insurance against lube related failures,,, I use Royal Purple 5W 30


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## GTOtbird (Mar 4, 2006)

Great response FergFlyer. I had a a '96 Tbird that after supercharging and switching to M1, I changed the oil every 6,000 miles or so. Ran it hard for four more years before selling to an Air Force Firefighter. Car is still going great. 


Since engine is under warranty, can't see changing the oil any sooner than recommended. I did get it changed the next day. Would be nice if engineers would give an estimated 'next oil change due' I was starting to think that maybe the oil monitoring system was not working.


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## fergyflyer (Apr 18, 2005)

GTOtbird said:


> Great response FergFlyer. I had a a '96 Tbird that after supercharging and switching to M1, I changed the oil every 6,000 miles or so. Ran it hard for four more years before selling to an Air Force Firefighter. Car is still going great.
> 
> 
> Since engine is under warranty, can't see changing the oil any sooner than recommended. I did get it changed the next day. Would be nice if engineers would give an estimated 'next oil change due' I was starting to think that maybe the oil monitoring system was not working.


The Corvette's oil monitoring system shows a percent of oil life left. I like that feature. I'm told the GTO's is set-up to trigger a need to change oil at 10% oil life left.


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## fergyflyer (Apr 18, 2005)

Sabraxas said:


> so I have a question for you Fergyflyer ( just out of honest curiousity ). Why does it say 'Premium gasoline recommended' for my GTO if I can run regular and get the same affects? Is there some performance difference or what? Thanks for any response.


The engine computer protects the engine from lower octane by running the fuel mixture richer and by retarding the timing. It listens for knock and adjusts till there isn't any. 

I've been told that by running 87 octane in the LS1 you would lose about 10% of the hp the engine makes. I'd guess the same is true for an LS2. GM rated the Z28 and the Firebird with the LS1 at 300-325hp and the C5 at 345-350 hp. Premium was/is required in the LS1 Vette, but wasn't in the F-bodies. I've heard that is how GM explained the rating difference. They tested the F-body with regular fuel and the Vette with premium. The reason most F-bodies put more power to the wheels was the owners usually used premium, so they actually made more power than what they were rated at.


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## GTOtbird (Mar 4, 2006)

FergyFlyer, if you're correct on the 10% then that would have been about 8,000 miles. This is what I have recommended for years to F&F since it split the difference between the test results obtained at 6,000 and 10,000.

My exact recommendations over the years have been: "Change your oil AFTER 6,000 but BEFORE 8,000 miles."

P.S. I'm a former Navy Diesel certified mechanic that monitored, tested, and purified lubricating oils on a daily basis for years using spectrometers and sediment testers. Of course, most F&F listen to the constant bay of the marketing hounds and not to the experienced experts.

P.S.S.
Here's another tidbit form an experienced expert that has been rebuilding engines for nearly 30 years. I asked him directly about the 3mo/3,000mi myth. He told me that the MAJOR reason the engines last longer and don't need as frequent an oil change was--the conversion from carbs to fuel injection. When starting an engine, the carbs would flood the cylinders with gas, wash off the oil, and metal to metal rubbing would occur until the oil pump replaced the oil. During the start up, combustion products and gasoline blow by the rings and into the oil-thus necessitating more frequent oil changes. This is not the case any more.


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## fergyflyer (Apr 18, 2005)

Check out this web site:

http://www.nordicgroup.us/oil.htm

It's from 2002, but the information is still valid today.


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## GTOtbird (Mar 4, 2006)

Thanks for the link, but I can hear the bay of the marketing hounds getting louder and louder..


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## Subdriver (Dec 28, 2004)

5,000 mile oil sample results on a 2000 C5 Corvette, which included one full track day at Watkins Glen, showing no ill effects of going past 3 mo/3k miles:
Corvette C5 Used Oil Analysis Report – AMSOIL SAE Synthetic 10w30
:cheers


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