ATF Change: Mileage vs DIC

[FL01SS]

So is anyone elses' DIC no where close to being accurate for the ATF life? I just hit 40k miles and my DIC still says 95%. When I purchased the car it had 32k miles & the DIC said 95% then as well. The Maintenance Schedule says the ATF & filter should be changed at 50K mi. I would assume my DIC should be reading 50% or less based on my current mileage. When I mentioned this to the dealership they told me the DIC is more of just a sales gimmick and isn't accurate in measuring ATF life and therefore the ATF should be changed based on the Maintenance Schedule. They also told me there isn't a filter in the trans & it's only a fluid change, even though the Maintenance Schedule says to change the fliud & filter.

Any thoughts?

[54inches]

Yes please, could someone with EXPERIENCE give some insight, because I have some Royal Purple waiting on a free weekend for my Tranny and my Dif.

[54inches]

I just found this:

http://www.transparts.ru/catalogs/gm/5l40e.pdf

Filters galore.

[1KWIKCTS]

The DIC is correct. Of course it has a filter. The dealership just wants to charge for sucking out the fluid and replacing it without dropping the pan and installing a new filter!!! You can change it as often as you like. I recommend at least 25000 mile intervals, but if it isn't abused (getting HOT) the DIC % can be used. The DIC will also know transmission temperature and adjust the oil change interval accordingly. I change my engine oil at 50% which is 5000-8000 miles since my driving is all highway!!!

[FL01SS]

Originally Posted by 1KWIKCTS

The DIC is correct. Of course it has a filter. The dealership just wants to charge for sucking out the fluid and replacing it without dropping the pan and installing a new filter!!! You can change it as often as you like. I recommend at least 25000 mile intervals, but if it isn't abused (getting HOT) the DIC % can be used. The DIC will also know transmission temperature and adjust the oil change interval accordingly. I change my engine oil at 50% which is 5000-8000 miles since my driving is all highway!!!

So you're trying to tell me that my DIC is accurate!!?!?! It states I have 95% life left at 42k!!!!! I don't beat my car, but I don't drive it like Mrs. Daisy is in the back seat either. It sees a decent amount of interstate miles, but more stop and go city driving. Plus, it's above 90 here in FLA a good portion of the year, which is one of the criteria for changing the fluid at 50k. Something isn't right when the manual says change it at 50K & mine is still at such a high % when I'm nearing that many miles. Will I see it start plumiting over the next 8k!?!?! I doubt it!!! If it was maybe around 80% I'd be more likely to believe that, but not 95%. The math isn't right & it makes me concerned that the DIC maybe isn't as accurate as we all want to trust that it is.

So what should I trust? A dealership that doesn't know enough about their own vehicles to know that there is a filter in the transmission (granted I just talked to the person at the desk who probably thought there wasn't a filter in the transmission since the dealership has one of those systems that flushes out the tranny through a cooler line without dropping the pan, but still), or a DIC that doesn't follow the guidelines of the maintenance schedule?????????

[dkozloski]

Here's all you need to know from the technical archive: [url]

Transmission Fluid Information (check this discussion for references): (back to the top)

Transmission fluid is not like engine oil. It is not exposed to blow by and by products of combustion. It does not see copius amounts of water from blowby on coldstarts. There is not much to deplete the lubricating characteristics of the trans oil and the antiwear and special friction modifier packages are very robust and stable. The temperature of the transmission fluid is pretty carefully controlled in the cooling development for the car. About the only thing that will shorten the transmission fluid's life is excessive heat and excessive heat for long periods of time. Since the modern transmission fluid has a high synthetic content it is pretty stable even at temps approaching 300°F. So...the things that govern and oil change in an engine do NOT apply to the transmission. Not at all.

The transmission fluid life "counter" in the display uses the transmission temperature as a means of judging the transmission fluid life. As long as nothing is done that the algorithm sees to shorten the life of the fluid it will stay at 100% virtually forever. If you start towing trailers or running extended heavy load operation you will see the transmission fluid life decrement fairly rapidly. If it is "stuck" on 100% then that means that the operating parameters that the PCM sees for the transmission fluid have all remained well within the guidelines for life time use of the transmission fluid. The transmission oil life monitor does not operate the same way the engine oil life monitor operates so you will typically see it stay at 100% in most cases.


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[54inches]

What he said.

[FL01SS]

Originally Posted by dkozloski

Here's all you need to know from the technical archive: [url]

Transmission Fluid Information (check this discussion for references): (back to the top)

Transmission fluid is not like engine oil. It is not exposed to blow by and by products of combustion. It does not see copius amounts of water from blowby on coldstarts. There is not much to deplete the lubricating characteristics of the trans oil and the antiwear and special friction modifier packages are very robust and stable. The temperature of the transmission fluid is pretty carefully controlled in the cooling development for the car. About the only thing that will shorten the transmission fluid's life is excessive heat and excessive heat for long periods of time. Since the modern transmission fluid has a high synthetic content it is pretty stable even at temps approaching 300°F. So...the things that govern and oil change in an engine do NOT apply to the transmission. Not at all.

The transmission fluid life "counter" in the display uses the transmission temperature as a means of judging the transmission fluid life. As long as nothing is done that the algorithm sees to shorten the life of the fluid it will stay at 100% virtually forever. If you start towing trailers or running extended heavy load operation you will see the transmission fluid life decrement fairly rapidly. If it is "stuck" on 100% then that means that the operating parameters that the PCM sees for the transmission fluid have all remained well within the guidelines for life time use of the transmission fluid. The transmission oil life monitor does not operate the same way the engine oil life monitor operates so you will typically see it stay at 100% in most cases.


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Thanks Koz!




:bigD:

[dkozloski]

Originally Posted by FL01SS

Thanks Koz!




:bigD:

Glad to be of help.

[Acqua7]

Originally Posted by FL01SS

Thanks Koz!