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Old 06-13-2011, 07:02 PM   #1
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Auxiliary Transmission Cooler

My tow vehicle is a 2008 Chev Duramax/Allison. Any thoughts on adding an auxiliary transmission cooler to back up the factory standard equipment?

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Old 06-14-2011, 08:51 AM   #2
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Well since no one else responded I will. I do not know exactly if its ok or not, however, I would say I personally would not worry about it for the fact that combo of motor and trans is a HD setup and I would feel pretty confident that the factory setup is sufficient. If in question I would contact Chevy service and speak to them, they would give you good advice.

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Old 06-14-2011, 09:04 AM   #3
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If your 2008 Duramax came with a heavy duty towing package, I can't imagine that your truck doesn't already have an auxiliary transmission cooler. Many newer heavy duty trucks also come with a transmission temperature gauge to keep tabs on that.

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Old 06-14-2011, 11:49 AM   #4
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I second the above postings. Also- Look into the grille on the front of your truck- you should see your large engine radiator- in front of that if you have an aux transmission cooler you will see a second smaller radiator.
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Old 06-15-2011, 10:08 PM   #5
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I have a 2005 Ford F50 XLT with the tow package. In front of my radiator, I have a smaller cooler for transmission. Also, my friend who is a transmission mechanic tells me almost all ford vehicles have a 3rd cooler for the power steering, alot smaller than the trans cooler. I guess Fords run hotter????
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Old 06-16-2011, 09:11 AM   #6
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Check the RPO codes that are listed in your glove box. If you have RPO code KNP you already have heavy duty transmission oil cooler. I think all the Duramax equipped trucks have this option.

If the RPO sheet is missing go to this web site:

Comprehensive Chevrolet, Saturn, GMC, Hummer, Cadillac, Buick, Oldsmobile, Pontiac, Geo, Dodge, Plymouth, Jeep, Chrysler, Ford, Lincoln, Mercury, Mazda Truck, Mercedes VIN Decoder

This site lets you enter your VIN then gives you a list of all the RPOs that apply to your vehicle. It will also tell you how many vehicles were built for your make and model year and how many vehicles were built with each RPO. According to this site there were 74,934 Chevrolets built with a Duramax, and there are 74,934 with the RPO code KNP. Therefore, I believe they all have the tranny cooler.

Make sure you use the correct VIN. This site lets you have a few free searches then locks you out for a period of time. Nice to have if you are looking for a used vehicle.

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Old 06-17-2011, 08:56 AM   #7
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There should not be any need for a different trans cooler on an 08 dmax. They beefed up the cooler on the 08's. Never heard of anyone having temp problems with them. I put a better cooler on my 06 but it had different stock cooler than your 08.

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