C5 auto trans fluid “high temp” warning

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Sep 24, 2021 | 11:25 AM

Bigspoker

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Heel & Toe

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From: Norcal

C5 auto trans fluid “high temp” warning

I just finished a track day in my 04 C5 coupe with auto trans. It was 100 degrees when we started, 97 when finished. During first session got “high trans fluid temp” warning on console

temp after session was 270. I let it cool and did two more sessions. Each time I was running between 220-280 then warning came on.
1) should I change trans fluid before next track day?
2) Do I need an add on cooler and what is the best made option? thanks!

Sep 24, 2021 | 12:07 PM

helga203

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Quote:

Originally Posted by Bigspoker

Was this ur first track with the car or u had many with no problems??

Sep 24, 2021 | 03:20 PM

Bigspoker

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From: Norcal

Quote:

Originally Posted by helga203

Was this ur first track with the car or u had many with no problems??

Third track day on same tran fluid. No problems on first two days but temp was 75 at first day 6 months ago; 90 at second track day 1 month ago. Car has 53k miles, 3500 since purchased from chevy dealer March 2020

Sep 24, 2021 | 03:48 PM

grinder11

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Quote:

Originally Posted by Bigspoker

270°F is mighty hot for an A4!! I'd change the fluid immediately. That or have it flushed. Used to be a rule of thumb that for every 20° increase in fluid temps over 200°F, 'useful' life of transmission was cut in half. You have surpassed that first 20° increase by a huge margin.......

Sep 24, 2021 | 09:31 PM

tabbruzz

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From: Central NJ

I would get a tranny cooler and bypass the rad cooler if you plan to track it.

Sep 26, 2021 | 12:54 AM

jim993

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From: Prescott, Arizona

I have been running my A4 on track, now starting my 12th year and 23rd track day coming up. Six days at Buttonwillow Raceway, 13 days at Laguna Seca and 3 days so far at Arizona Motorsports Park.

Of the above tracks, the transmission runs warmest at Arizona Motorsports Park on a 95+ day, next Laguna Seca on a 90+ day.

In order to keep the transmission cool I have added a DeWitts radiator with both transmission cooler and engine oil cooler, a B&M finned aluminum transmission pan with extra capacity and an auxiliary transmission cooler in front of the condenser.

The auxiliary transmission cooler is plumbed in series AFTER the DeWitts radiator cooler. In addition I run Red Line D4 full synthetic ATF for better protection against oxidation of transmission fluid when HOT.

On track I only use 2nd and 3rd, monitor the DIC for transmission temperature and decide to come off track if transmission temperature hits 250.

Sep 26, 2021 | 05:58 PM

grinder11

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Quote:

Originally Posted by Bigspoker

I will also add that a higher stall converter is going to make the trans run hotter, all other things equal. I'm not saying you have one now, just a bit of advice if you're thinking of adding one. Jim 993 has a good setup, with cooler AFTER the radiator, and a good rule of thumb parking it after 250°. I'm sure the 'old school' rule of thumb I gave you has changed for the better since the advent of synthetic fluids. But 270° is HOT no matter how you care to look at it.....

Last edited by grinder11; Sep 26, 2021 at 06:00 PM.

Sep 27, 2021 | 08:05 PM

gimp

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From: San Jose, CA

For the A4, I'd probably go as far as to change the fluid after every track day if you're hitting it hard. And if you're hitting it hard regularly, a dedicated cooler can definitely do better than the shoddy integrated one, which is not at all meant for track days.