# Yet Another Damned Oil Change Question



## Groucho (Sep 11, 2004)

My GTO just turned over 10,000 miles. 

I have had the oil changed religiously each and every 3k miles...the first two changes were with conventional "mineral" oil. With the engine well broken it, I switched to Mobil1 synthetic at the 9000 mile change and plan on staying with it for the rest of the time I own my Holden. 

I've recently accepted a new job. My new commute is going to be ~210 miles each day RT. The vast majority of that drive (about 160 total miles of it) is open freeway, 75-80mph @ 2100 RPM 6th-gear loafing in cruise. the other 50 will most times be varied-throttle with some stop & go traffic stuff.

If I were to keep to the stated oil change, I would have to change it _once every three weeks_ from the commute _alone_. Ka-ching.

I know, I know. Oil changes are cheap insurance. But _bloody hell _that is a lot of work / money....once every 3 stinking weeks sounds _really_ excessive.

My question is this-- with most of my commute being freeway miles, would I be OK changing the synthetic oil & filter every 6000 miles?


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## DaddySS (Dec 20, 2004)

According to the oil life studies, and mobil 1, their synthetic should be good for 7500 + miles (up to 15,000 depending on dusty conditions etc.). We change it at 3000 because we're anal and we want it to be as clean as is reasonably possible. With your new commute and mostly highway driving, 7500+ miles betwen changes should be no problem. After 3000, I would start to monitor the color, and change when when it starts to look dirtier than you are comfortable with.


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## Xman (Oct 31, 2004)

I would run 10,000 miles on my Camaro with Mobile 1 and I had no issues or overly dirty oil at changes. I plan on using Amsoil this time and plan on 12-month changes which will be about 15,000 miles for me. I started changing at 10,000 on all my cars (they all are synthetic) because I can remember when the oil needs to be change. I to often forget or lose the book I wrote it down in if I did anything but changes at 5K increments.


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## Tom (Nov 1, 2004)

I spoke with a GM engineer about the oil change light. he thinks it is a pretty neat device. it takes a lot of factors into consideration. he said he saw it vary on one car he had for a long time depending on the weather and other factors.

I say use synthetic and change when it comes on. the light is set up for dino oil, synthetic is supposed to last at least 3x longer, so using the light under light load should be a good middle ground.

i use the light on my wife's aurora. and replace it with mobil 1.

Also, congrats on the new job.


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## UrassisDragon (Dec 7, 2004)

I agree with what DaddySS stated in his post. 7,500 miles is no problem with your long daily commute. The only advise I would add is that you change your oil filter at every oil change no matter what the mileage, whether the oil is dino or synthetic!!!


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## catchmeifucan (Sep 12, 2004)

Well, I would agree that you should be able to extend the life of your oil to at least 7,500 miles with your highway driving.

But, one thing to consider - the warranty (GM and Extended)

I had a Ford car that had just went out of the factory warranty. And, I had purchased a extended warranty through Ford. At about 40K, the lifters starting tapping. Ford essentially refused to cover the engine work because I could not demonstrate that I had changed the oil per their recommendations. 

So, since the GTO has a sensor (is this truly a sensor or just mileage driven anyway?), I would assume the mileage in between would extend out with this highway mileage. I would just take it to a local dealership and have them change the oil as needed. This way you should get the extra miles between changes and they can't argue about meeting their recommendations and that the job was done by their own trained mechanics.

I would prefer to change my own oil myself. But, after this experience with Ford, I will continue to pay a few extra dollars have the dealership change the oil until that warranty expires.


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## UrassisDragon (Dec 7, 2004)

catchmeifucan said:


> Well, I would agree that you should be able to extend the life of your oil to at least 7,500 miles with your highway driving.
> 
> But, one thing to consider - the warranty (GM and Extended)
> 
> ...


 This sounds strange but I remembered reading about When to Change Engine Oil (GM Oil Life System) a few weeks ago and it mentioned in the GTO owners manual about not pertaining to mileage of the engine but being based on other factors. So I just now got out the owners manual again so as to read that section. I opened the manual to 5-16 and this is a quote from the 04 GTO Owners Manual as follows: Your vehicle has a computer system that lets you know when to change the engine oil and filter. This is based on engine revolutions and engine temperature, and not on mileage. Based on driving conditions, the mileage at which an oil change will be indicated can vary considerably. For the oil life system to work properly, you must reset the system every time the oil is changed.

When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A Service Engine Oil message will come on. Change your oil as soon as possible withen the next two times you stop for fuel. It is possible that, if you are driving under the best of conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, your engine oil and filter must be changed at least once a year and at this time the system must be reset. 

Then it goes on about what to do after having reset the system accidentally. Incidentally, the next page 5-17 How to Reset the Service Engine Oil Message, tells you how to reset the (GM Oil Life System) with your accelerator pedal.

Myself, I will make the first oil change with filter at 2,000 miles which is a few miles away. Then it will depend on when the oil Life system comes on or if I get uncomfortable with the mileage before it comes on. Somewhere on one of these forums I seen an owner who has 8,000 miles on his GTO and has no oil change light come as yet!!! If I was him I would take it in for oil and filter change and have the system checked out. Never know if there could be a failure in the warning system. Hope this helps!!!


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## Snafu (Aug 27, 2004)

Everything they said is spot-on...oil change every 7k-10k miles should be fine given the conditions.

All I have to say is...Damn! That better be a good job for 210 miles a day!!!!  Didn't you work for Burt Rutan before?


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## Jon Baumgardner (Nov 10, 2004)

Change the oil when the oil change indicator light comes on. Do not worry about it. The car will monitor for you.

Don't fret it!! Do not sweat the small stuff!!

Go luck in your new job.


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## Groucho (Sep 11, 2004)

Great info all, and thanks for the help. My BMW had a 15,000 mile oil change interval (using their $pecial $ynthetic), but after she hit 100k miles I went with a 7500 mile interval _just because_. Seems a nice, round, safe number. I'll eyeball the condition of the oil and let that help guide me.



Snafu said:


> All I have to say is...Damn! That better be a good job for 210 miles a day!!!!  Didn't you work for Burt Rutan before?


Yes on both...I've been working for Burt's company for 13 years now, but after the space flights I got singled out by a headhunter for another R&D outfit (non-aerospace related, more high-tech) down in the L.A. area. They made me an offer I could not refuse, working for a very cool company doing all kinds of cool stuff-- they even do R&D work for GM! 

I'll move eventually but have just bought a house in BFL plus kids in High School so I'm stuck for while doing the commute... In the mean time, I guess I own the GTOfoums.com Official High Mileage Test Bed.  

Luckily, the GTO is one hell of a nice Autobahn Panzer...though I may prematurely smoke a clutch ion L.A. traffic!


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## Subdriver (Dec 28, 2004)

Concur with the other posters above that you can safely go well beyond 3000 miles with modern synthetic oils. AMSOIL warranties its PAO based SAE synthetics for 25,000 miles or one year of use. Mobil just came out with an extended drain line of oils that is rated for 5000, 7500, or 15,000 miles depending on which one you get. As a note, they haven't come out and said what mileage Mobil 1 is rated for. I would suggest that it is safe to use up to one year or the oil life monitor. 

From my understanding of the Corvette oil life monitoring system, which I would assume is the same or very similar to that on the GTO, fuel injector pulses are counted as a way of measuring engine load, rpm, etc and hence play heavily into the oil life monitoring system.

One caution though, and I believe this bit Mercedes, is that the oil life monitor calulations are based on a certain type of oil (e.g. dino oil or synthetic). The Corvette is calibrated for a PAO based synthetic (Mobil 1 in this case) so putting a dino oil in a Vette and expecting the oil life monitor to accurately monitor oil life is a bad plan. My wife's Chevy Trailblazer on the other hand does not require synthetic, so running a synthetic and going all the way to 5% (or one year) on the monitor is conservative. 

Here are a few interesting articles on oil life written by the editor of Lube's and Greases which should give you a little piece of mind for going beyond 3000 miles:
Motor Drain Intervals: How Long Must We Wait?
Motor Oil Drain Intervals: An Ethical Burden?

:cheers


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## gclcpa (Jan 9, 2005)

The 2003 Grand Am GT that I traded in on my GTO also had the oil monitoring system. I got usually around 8,000 to 8,500 miles before the light came on.


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## Guest (Feb 24, 2005)

*Money!*

Oil And Filters Are Cheap,even Mobil One Is Cheap Compared To Hard
Engine Parts And Labor ,pay Now Or Pay Later !


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## Guest (Feb 24, 2005)

*Hair Cuts,banjos*

[edit] Keep it civil [/edit] TR


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## Groucho (Sep 11, 2004)

ramairws6 said:


> WHAT YA SWEATING GRUMPO WE BANJO PLAYING MULLETS CAN AFFORD TO
> CHANGE OUR OIL AT 3,000 MILES REGARDLESS, MAY BE THE NEW BURGER KING YOUR WORKING THE DRIVE IN AT WILL TRANSFER YOU BACK TO KFC.
> BUT I know COOKING OIL IS IN YOUR VEINS, YOU CHANGED THE OIL AT KFC
> 3 TIMES A WEEK SO WHATS YOUR" BEEF" LOVE "JOE DIRT"



Yeah.

OK.

Thanks for that...


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## Scissors (Jul 27, 2004)

One of the Corvette guys sent his oil (Synthetic Mobil 1 5W30) into the lab after it was changed in accordance with the oil life monitoring system. The lab said that the oil was in excellent condition. It didn't even need to be changed yet; and this was after 7,000-some-odd miles.

Every 3,000 is a waste of time and money and harkens back to older automotive technology. Materials and chemicals have changed since then.


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## Kruul (Jan 14, 2005)

I think I'm going to use the oil analysis route. Testing is cheap enough and problems show up early. We use this system where I work and the numbers dont lie.


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