2004 Grand Prix Series III 3.8L DIC based OCI

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Background: I have a 2004 GP that I put heavy mileage on (minimum 600 miles per week) 100% highway driving. I have used the lowest cost on sale 5w30 conventional (it has had everything, Castrol GTX, Shell Formula, etc.) since new with 7500 mile OCIs. The car requires .5 Qt. makeup between changes.
Question: This car is factory equipped with an oil life monitor in the DIC (Driver Information Center), it is nothing fancy just an algorithm based on my driving habits. I stick to the 7500 mile OCI but the monitor consistently lasts out to the 11000 - 12000 mile mark (I don't reset it). Has anyone pushed a Series III this far? I am at the EOL maintenence point in this car now so 11 - 12k changes appeal to me.
 
I might move up to 8 or 9K if the oil life monitor OK's it but I wouldn't go beyond that on dino oil. I'm not even sure if I'd go beyond that on synthetic but I would feel more comfortable going near 10K on full syn. (versus dino).

PS: The algorithm based OLM on my Buick 3.1 always seems to light up at approx. 6500 miles. My driving is about 65/35 highway/intown.
 
Hey a fellow GP driver. I have gone down to around 11% (9K or so miles) on my OLM when using synthetic, but didnt have the gonads to go any longer. I am like you if I listen to the OLM it will take me out to around 11K mile OCI. I say use a decent synthetic and oil filter and follow the OLM. Are those 600 miles highway or city? If highway go by the OLM, if city then cut it short. FYI I only have the 3 button information center so I rely on my Onstar report to give me my percentage. How many miles are on your 3800?
 
The OLM on a GP is geared for dino and runs down to 0% at about 10,000 miles. The 3.8 engine is pretty easy on oil and I change mine around 6-7,000 miles now. So figure 1,000 miles for each 10% on the OLM. I have a '07 GP GT (S/C) and run synthetic oil.

Someone told me that running synthetic oil on this engine won't give me any noticeable benefits for the first 100,000 miles but should be helpful in reaching 200,000.
 
Lots of 3800's out there running dino oil for 5-6k miles that have 150k+ miles on them. Oil isn't a big thing in these cars. The lower intake gaskets for Series II and 4T65 issues are more pressing.

The Fit does 10k+ mile change intervals according to its OLM. I run synthetic in it for peace of mind.
 
Originally Posted By: Neil_A
Hey a fellow GP driver. I have gone down to around 11% (9K or so miles) on my OLM when using synthetic, but didnt have the gonads to go any longer. I am like you if I listen to the OLM it will take me out to around 11K mile OCI. I say use a decent synthetic and oil filter and follow the OLM. Are those 600 miles highway or city? If highway go by the OLM, if city then cut it short. FYI I only have the 3 button information center so I rely on my Onstar report to give me my percentage. How many miles are on your 3800?


Hi,

Yes the 600 miles are all 100% highway minus the few mile drive to the freeway from my house. I have 115000 miles on the car right now. This is just my commuter beater but it is the best daily driver car I have ever owned, an alternator is the only extraordinary maint. cost to date. Fuel economy is great and it is a really nice car to drive. I am looking at replacing it next year (I'll be at 150+ by then) with another GP. It will have to be used of course... they are no longer made.
 
I have a 3.8 Liter 2001 Chevy Impala. Been doing 7500 mile oil changes on it using Mobil 1 10W-30. Now has 121,000 miles. Did 10,000 once with Mobil 1 EP. No engine problems except a 40,000 mile lifter/cam failure, which they covered under warranty (I had mentioned loud lifters before 36,000 miles).
 
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Originally Posted By: sciphi
Lots of 3800's out there running dino oil for 5-6k miles that have 150k+ miles on them. Oil isn't a big thing in these cars. The lower intake gaskets for Series II and 4T65 issues are more pressing.

The Fit does 10k+ mile change intervals according to its OLM. I run synthetic in it for peace of mind.


I've done the LIM, UIM, and shift kit to correct 4T65 problems on 03 3800. Runs and shifts like new at 206K. I enjoy changing oil too much to run longer than 5-6K OCIs, though.
 
I enjoy changing things like oil every once in a while. Right now the Buick will be running 10k miles on Castrol Edge 5w-30. I'm not worried about LIM gaskets since mine were done a year ago. Oil pan gasket was recently done, too.

For the OP: If you're going to run 10k+ miles change interval, I'd suggest a name-brand synthetic for peace of mind and better flow in those cold Alberta mornings.
 
Originally Posted By: marc1

I am looking at replacing it next year (I'll be at 150+ by then) with another GP. It will have to be used of course... they are no longer made.



Why replace it? Those 3.8l engines are good until at least 250,000 miles!

Heck, the subframe will rot out before the engine gives.
 
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Originally Posted By: [email protected]
Originally Posted By: marc1

I am looking at replacing it next year (I'll be at 150+ by then) with another GP. It will have to be used of course... they are no longer made.



Why replace it? Those 3.8l engines are good until at least 250,000 miles!

Heck, the subframe will rot out before the engine gives.



I agree, why replace it if it's still running good? I have 136k miles on my '01 GP with the 3800 and I plan to run it to 250k+ miles if the car is willing. I put about 22k per year on it now, I drove it a lot less when it was newer and hardly at all one year. I don't think the subframe will rot out on his, the 04+ models had an aluminum subframe if I remember correctly.

I've run mine out as far as 9785 miles with a UOA. Here are the results.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1868816
 
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We're nearing 200K on our Series II. Original drivetrain. Both the engine and trans feel solid enough that I think 300K is going to be easily obtainable.

All highway driving? I bet you could get 500K out of a Series III drivetrain pretty easily if you keep up with maintenance. Make sure and change the coolant well before the 5 years/150,000 miles though.

As for oil, get a UOA. I bet 10,000 miles would be obtainable with any quality name brand conventional oil, but you can routinely find synthetics on sale for around the retail price of conventional, and it would easily do 10K all highway in a 3.8L.
 
sounds like u have a good plan . I run a lot of miles myself, usually 8k to 10 k a month. I run Rotella t-6 5w40, with a quart of MMO. Im also using 2 cycle oil in the gas tcw3, at 35 gallons a fill up I need all the mpg I can get. Currently 16.5 to 17.39 depending on the loads I carry.
 
Don't Replace - Yeah I know and I love the car but I like to get out of Dodge before heavy repairs come along (transmission, electonics, etc.). The trick is knowing how far to push it. The motor, I agree, is sound and runs so well 250k would be easy... the rest of the car though... not sure. Yes it is an aluminum SF so no worries there and the body and interior are still mint.

Syn - I am just not quite there on a cost benefit POV... I have never used syn and never had any lube related engine trouble in the many different vehicles I have owned... light duty and severe duty. My oil change costs on this car are $12 / change and the engine will out last the car... so I can't justify it. I respect syn users right to choose and don't question their decisions, it is just not right for me and certainly not for my daily driver.
 
Originally Posted By: marc1
Don't Replace - Yeah I know and I love the car but I like to get out of Dodge before heavy repairs come along (transmission, electonics, etc.). The trick is knowing how far to push it. The motor, I agree, is sound and runs so well 250k would be easy... the rest of the car though... not sure. Yes it is an aluminum SF so no worries there and the body and interior are still mint.



Hey it's your car, your money and ultimately your choice but I'd agree with everyone recommending you keep it. 150k is NOTHING for any decently built car. Its unlikely and major expensive probs are gonna happen before 200k and if you buy a used one who knows what you're getting? Sorry to push the idea but IMO getting rid of it for another used one makes no sense. It's pretty low in miles and years, and you know it inside out now.

As far as the OCI question goes I wouldn't dream of taking it to 10+ k on dino. Even your easy on oil all highway deal. I'd either put a top line synthetic in there and follow the OLM or just do what you've been doing, change at 7k or so on a good dino and know that everythings taken care of as well as can be. Or, and I can't be bothered to do it in my rides, do a UOA and know exactly where the limit is. But I understand why so many don't want to do it, if you're running dino, you could just change it for the price of a UOA.
 
Im closing in on 200k in my car. Its starting to show some signs of wear, but the engine still starts every morning.

Ive ran just about every brand of oil you can think of in it with no problems, sometimes mixing different brands together.
 
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