2012 5.3L Yukon XL

fosstugz wrote:
So I pulled it home over the weekend without a towing issue. The ambient temp was 55F and on the highway, locked it on 4th gear, it seems the trans temp sweet spot was ~194F. However, after the 3.5hr tow home, driving through town got me to 210F buy the time I got to the house. This was concerning to me. What was also concerning to me was the fact that it was rather cool this weekend. I'm afraid now to see what the trans temp would be when summer temps start to roll around.

I'm still concerned than a stacked plate cooler won't help me out much since my temps are the highest when in town or in stop and go traffic. I can't imagine that the cooler would be very effective without airflow passing through it. Some tell me if I'm wrong about this thought process.

Yeah, and the 7mpg was a bit lower than I was expected..... ;)

Towing in stop and go is tough on any TV...worse if it has an automatic

Ditto hills...also worse if it has an automatic

Yes, it will get worse when the ambient gets higher and where you live
it will get lots higher. Ditto the inclines of the mountains of the West
Coast.

This is because there is less air flow in city driving (laws of
thermo dynamics) and that the tranny TC (torque converter) is
unlocked for torque multiplication to get it moving. Since unlocked,
the TC has anywhere from 10%-25% losses in efficiency (turned to heat)

That is a ditto going up inclines when the tranny unlocks

There is an electric aux fan on most GM full sized automatic with the
tow package. That fan comes on with either the AC and/or when the ATF
gets above a certain temp

Referencing a 'stacked plate' is out of context.

A tube and fin can have several times more cooling than a stacked plate
and what is missing are their respective sizes

The biggie is where they are mounted

Here is my GMT400/1996 8,600 GVWR Suburban with it's front clip removed
while in the body shop (a Land Rover jumped a stop sign and I nailed him)



The Fan is in front of the AC condenser. The auto trans fluid (ATF), stacked
plate cooler is on the opposite side of that electric fan.

Increasing the size of your external ATF cooler will help. Adding
an electric fan will help even more...but...only so much in reference
to what you are towing.

Manageable as long as you don't pack much and keep it SLOW, both in city
and out there on inclines.

My 17 year old 1996 8.6K GVWR Suburban with a 7.4L engine gets 7-8 MPG
towing trailers up to Lake Tahoe and that is some times better than
small blocks (about 1.5 times smaller than my big block). That says
the small blocks are working VERY HARD, while my 7.4L is loafing along

My diff ratio is 4.1 and ask what is yours

How was your Suburban loaded? Repeat best to go out and weigh it fully
loaded, ready to go camping...axle by axle to know where you are in reference
to your ratings