Trans and fluid question....

**GoldGTP** · 12-28-2011

Hello again, and let me re-iterate this message board is a wealth of info!

I have a quick question about the tranny in my 03 GTP...

Say I am travelling down the freeway at 65MPH...

If I let off the gas, the RPMs drop to idle speeds (~1k), and if I start to accelerate again, the RPMs have to "catch-up" before the car starts to accel...

Also, I accidentally popped it into Neutral while going down the freeway, and I noticed my speed dropped to Zero, but in-fact I was travelling 65MPH..

Some kind of speed sensor shot?

Also, I was wondering if anyone knows where I can find the classic Dexron 3 fluid....

And alas, if anyone has pointers for a tranny fluid change, I am open ears!

Thanks again msg board,
GoldGTP

**TLSheff** · 12-28-2011

Most parts stores should still sell Dex3, in different brands. I know they should because the GM Dealership I work at still sells Dex3, but we order Mobil Dex/Mer 3 by the case.

Service is just drop pan, replace filter, 7-8qts back in tranny and good to go.

The sensor, I have no idea

**Zef_66** · 12-28-2011

Originally Posted by TLSheff

Most parts stores should still sell Dex3, in different brands. I know they should because the GM Dealership I work at still sells Dex3, but we order Mobil Dex/Mer 3 by the case.

You have to use a Mobil product because GM does not support, produce, or recommend to anyone that Dexron III fluid be used anymore. It is an old, unsupported, and obsolete product. In fact, they stopped licensing around the end of 2006. So any Dexron III fluid made after that date is unlicensed, uncontrolled, and not something I would want to use at all. Your best bet is to go with the newer and better in all aspects Dexron VI fluid. Definitely a better choice.

The highway RPMs thing when you let off is normal. Nothing wrong, and the only way to change that is with a tuner as far as I know.

I'm not sure about the speedo in neutral. If it was just a one time thing, I would do it again and see if it replicates. The only thing that I can think of is a failing CPS (crank postion sensor) but that doesn't seem right. See if you can do it again and confirm exactly what it does.

**Logan541** · 12-28-2011

Take off return line attach a piece of clear tubung remove dipstick put car in neutral and have someone start it.Keep adding fluid until the fluid coming out the return line looks like fresh fluid, Stop engine drop pan change filter clean and replace pan. Top off fluid doing it this way you also flush out the convertor. Its a pain and its messy but the other way you only replace half the fluid.

**TLSheff** · 12-28-2011

Nothing against flushes Logan, but if it is a higher mileage car and hasn't been maintained properly, with regular services as needed, there is a possibility that a complete flush like that would cause more problems than it would fix.

Seen several that come in with problems and they get a full flush like that and it cleans the old fluid out along with everything that was clinging to the clutches and still allowing it to run.

Now it the car is lower miles and regularly maintained and not having any problems, its up to you. Most just recommend a pan drop and new filter/fluid. Just FYI.

**Logan541** · 12-30-2011

Originally Posted by TLSheff

Nothing against flushes Logan, but if it is a higher mileage car and hasn't been maintained properly, with regular services as needed, there is a possibility that a complete flush like that would cause more problems than it would fix.

Seen several that come in with problems and they get a full flush like that and it cleans the old fluid out along with everything that was clinging to the clutches and still allowing it to run.

Now it the car is lower miles and regularly maintained and not having any problems, its up to you. Most just recommend a pan drop and new filter/fluid. Just FYI.

I forgot that and ou are right see I do full flushes BUT then again I am the original owner and have flushed it that every 50,000 miles since I got it. You are coreect though that could mess up a car that has not been maintained properly sorry guys I just did not think of that.

**GoldGTP** · 02-29-2012

Forgot to post back, but alas this board doesn't disappoint....

Thanks for the tips and the fluid change was a breeze...

Really appreciate it.

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