just add a tranny cooler,if your tranny gives you problems like not shifting etc,then it needs a rebuild,,,,the tranny fluid running hot is normal and can be fixed with a tranny cooler kit, Derale Series 8000 Plate Fin Transmission Cooler Kit Barb Inlets Class III...
,its a van,it is going to get hot,get a kit and hook it up,and see the difference,replace all o2 sensors while you are at it,they are cheap and if 1 goes then the others will go,and then you only have to be under it one time,not a couple times,here is info i found;
Transmission coolers are not vehicle specific, but there are ones that are recommended for certain engine sizes. What I did was look up the recommended coolers for the 4.8 liter engine for the 2008 Silverado to get an idea of what we recommend for that engine size.
The most popular cooler for the 4.8 is the Derale Transmission Cooler, # D13502
, and GM fitting, # D13035
. The cooler is listed for a load of up to 3,500 pounds. Before deciding on a cooler though it will be a good idea to look at the dimensions, listed on the product page below the description, to determine the best place to mount the cooler in the engine compartment.
I have included a link to a video showing a typical installation and a link to our FAQ article on transmission coolers for you to view.
Engine oil coolers would also be beneficial to extend the life of oil lubricated parts. The kits work well and from the information that I have received from Derale in the past, any restricted flow is so minute that it may not even be able to be detected.
I recommend the Derale Tube-Fin Engine Oil Cooler Kit, # D15501
. The adapter has a 2-3/4 inch o-ring diameter which is used on the vast majority of GM applications. It also has multiple threads to ensure proper thread size. Again, you will want to check the dimensions of the cooler and compare that to the space under the hood of your 2008 Chevy Express Van ahead of time.
Both the transmission cooler and oil cooler come with all the necessary hardware and parts for installation. Current pricing information is available on each of the product pages.