Sierra 1500 transmission cooler

nfisherman · February 5, 2015

I bought a 2015 Sierra 1500 SLT All Terrain w/5.3 this week. I love the truck so far. I tow a fair amount, probably 5,000 miles per year. I'll be towing my boat or my camper, each weighs about 3,500#. I know the trailers are fairly light. Would it be worth the cost to add an auxiliary transmission cooler? I asked my dealer's service department and they said it isn't necessary. They said I have a heavy duty transmission cooler built into the radiator. I have no reason to doubt that the dealer is technically correct. I'm just wondering if a adding an additional cooler would give me a significantly longer transmission life. I towed a lot more with the Yukon that I traded for this truck. I had over 150,000 miles on it and I never had a hint of transmission trouble...but I added a cooler. What do you think?

LongrangeLauber · February 5, 2015

If your truck came with the tow package (tow bar, trailer brake controller) it already has an auxiliary trans cooler. Thing that sucks about these trucks is there is a built in thermostat on the trans so it doesn't open fully until 192 degrees.

I tow 5k lbs around quite often since I've gotten the truck and it doesn't struggle. I tow up and down hills and it does great. Just keep it in tow/haul mode and you're good to go

nfisherman · February 5, 2015

Thanks. I do have the trailer hitch and brake controller. I won't be towing for a couple of months. I'll watch the transmission temperature the first couple of times out and see how it does.

LongrangeLauber · February 5, 2015

I haven't had mine go above 205 and I push the truck hard lol. I guess when the tstat opens it does do its job thoroughly. You can watch the trans temp while not towing as well. It sits right around 192 unless you're racing it and such

SouthernSilveradoGuy85 · February 5, 2015

If your truck came with the tow package (tow bar, trailer brake controller) it already has an auxiliary trans cooler. Thing that sucks about these trucks is there is a built in thermostat on the trans so it doesn't open fully until 192 degrees.

I tow 5k lbs around quite often since I've gotten the truck and it doesn't struggle. I tow up and down hills and it does great. Just keep it in tow/haul mode and you're good to go

Mine doesn't have the trailer brake but still has the trans cooler. Om the build sheet it says "KNP - TRANSMISSION OIL COOLER". I figure as long as it came with the Z82 Trailering Equipment Package (basically hitch and trailer electrical for the most part) it should have the trans cooler.

Silverado-Hareek · February 5, 2015

If your truck came with the tow package (tow bar, trailer brake controller) it already has an auxiliary trans cooler. Thing that sucks about these trucks is there is a built in thermostat on the trans so it doesn't open fully until 192 degrees.

I tow 5k lbs around quite often since I've gotten the truck and it doesn't struggle. I tow up and down hills and it does great. Just keep it in tow/haul mode and you're good to go

I don't think this is accurate. The transmission cooler you're referring to is built into the radiator. GM also offers a separate auxiliary cooler that you can add in addition to the cooler in the radiator. As far as I know, most people that have the tow package do not have this separate auxiliary cooler unless your truck happened to come with it or you paid a fee to add it either when building the truck online or purchasing it from the dealer. I don't know about the K2 trucks but my 2007 Silverado didn't come with a hitch reciever or trailer wiring harness but I had them add it. I did have the cooler in the radiator but I doubt they added that too since they added the tow package for free. I'm pretty sure all trucks, and every vehicle for that matter, cool the transmission fluid in the radiator....you have to or the transmission will overheat. Maybe the ones with a tow package have a slightly larger capacity cooler in the radiator?

EDIT: Just did some research on the Chevrolet website and I don't see the auxiliary cooler as separate option anymore. Maybe they changed it and I'm mistaken on my original post? Sorry for the incorrect information if I am.

LongrangeLauber · February 5, 2015

I don't think this is accurate. The transmission cooler you're referring to is built into the radiator. GM also offers a separate auxiliary cooler that you can add in addition to the cooler in the radiator. As far as I know, most people that have the tow package do not have this separate auxiliary cooler unless your truck happened to come with it or you paid a fee to add it either when building the truck online or purchasing it from the dealer. I don't know about the K2 trucks but my 2007 Silverado didn't come with a hitch reciever or trailer wiring harness but I had them add it. I did have the cooler in the radiator but I doubt they added that too since they added the tow package for free. I'm pretty sure all trucks, and every vehicle for that matter, cool the transmission fluid in the radiator....you have to or the transmission will overheat. Maybe the ones with a tow package have a slightly larger capacity cooler in the radiator?

EDIT: Just did some research on the Chevrolet website and I don't see the auxiliary cooler as separate option anymore. Maybe they changed it and I'm mistaken on my original post? Sorry for the incorrect information if I am.

It sets on top of the a/c condenser but it looks like one unit. You will know if you don't have an auxiliary trans cooler when your trans temp spikes when you go to tow. I'm pretty sure all 2014s come standard with it

Spurshot · February 5, 2015

Keep an eye on the temps. If it runs 220f or less, you'll be fine. But that temp reduces the ATF life. Just driving around town with an empty truck, I see over 190f because the fluid runs thru a heat exchanger in the radiator coolant.

I'd change fluid often if I towed anyway. Once a year couldn't hurt anything except you lunch money for a week.

If you add an aftermarket cooler, route the fluid thru the stock radiator cooler first, then the aftermarket cooler.

nards444 · February 5, 2015

with that type of weight hauling I wouldnt worry about it

gone_fishing · February 5, 2015

From the GMC website:

External transmission oil cooler

-Heavy-duty air-to-oil cooler

-Standard on SLT models

-On Sierra and SLE models, included with available 5.3L EcoTec3 V8 engine

Sounds like all 5.3 V8's will have an external transmission cooler.

redwngr · February 6, 2015

Mine doesn't have the trailer brake but still has the trans cooler. Om the build sheet it says "KNP - TRANSMISSION OIL COOLER". I figure as long as it came with the Z82 Trailering Equipment Package (basically hitch and trailer electrical for the most part) it should have the trans cooler.

For 2014, RPO KNP Cooling, auxiliary external transmission oil cooler

is Included and only available with (L83) 5.3L EcoTec3 V8 engine.

Z82 trailer towing and JL1 integrated brake controller say nothing about enhanced cooling.