HOXXOH

Mine had the new stuff and I only changed it at 98K miles at the request of the dealer who wanted to be sure the noise was a wheel hub and not the rear gears.

Mine has a born on date of 10-30-07. What's your's?

Cherokee Nation

February 2008.

Cherokee Nation

I did not have my changed until sometime in 2009.

HOXXOH

My only possible explanation would be that the stock of the 2.56 and 3.42 gears ran out earlier than the stock of 2.73's. That's all I got.

Cherokee Nation

I have 273 gears,anyway the service manager said that the new oil was added to the 2009s which would of been released for sell in the last quarter of 2008 or?

RobJoy

1. Don't remember where I saw this but info referred to Mobil 1 oil needing temps above 200? degrees in order to burn the engine contaminants out of the oil thus keeping it cleaner and stable over a longer period of time.
2. Yeah. An earlier-opening t-stat is not necessarily going to keep an engine from overheating.
3. Retaining the underbody spoiler at the front of the car will push air up and thru the radiator whereas removing the spoiler (deflector) will cause the air passing under the car to draw incoming air thru the grille down and away from radiator so that it doesn't pass thru the radiator, and can lead to overheating.
4. Guy who tuned my LS-3 after cam job set up radiator fan for staged cooling up to 217 degrees at which point the fan runs at maximum, but not greater than 88% since it seems this is where GM wants to keep it so the fan electrical connectors will not start to overheat and degrade.

Mike's LS3

1. I installed a 160* T-stat and have an EOC in my Dewitts radiator and normal oil temps are around 220*. Yes, the 200*+ oil temps will help burn off moisture and contaminates in the oil pan.

2. Yes, a lower T-stat will not help overheating. However, a lower T-stat starts the cooling process sooner which help keep average coolant temps down along with reprogramming the fan duty cycle. Opening the T-stat later and using the stock fan duty cycle keeps average coolant temps in a higher range. This is what the car was designed to do for emissions. At idle or stop and go traffic, coolant temperature is dependent on air flow thru the radiator and cooling capacity of the radiator. If the coolant process starts sooner and the fan is programed to start sooner your average temps at idle or stop and go traffic will be reduced. However, once radiator air flow becomes insufficient and ECT's rise, the T-stat has passed the opening point and will not prevent overheating.

3.

4. GM"s tune sets the fan at 90% maximum, and yes any higher risks melting the fan connector. One method in preventing this is to by-pass the connector by soldering the 3 wires directly. Even though I have by passed the connector my max fan setting is still 90% starting at 210*F.

Yokesc5

Mike's LS3

Would you agree on a hot day coolant temps will easily reach 200*F? If so, once coolant temps reaches 200*F both the 160* and 187* (oem) T-stats are fully opened and coolant flows thru the radiator at the same rate. The t-stat has done it's job! The fan is designed to work at idle and low speeds, then shuts off as you increase to highway speeds.

GM designed their t-stats to fail in the open position to prevent overheating!

HOXXOH

At 110* ambient I can drop the temps to 175-180 with a 160 stat if I drive at a steady 60 MPH. I couldn't do that with a 187 stat. The fan doesn't move air fast enough even at 90% at low car speeds.

Vette_Fan

When I called the dealer about the tranny fluid change, and my concern about it, he said he'd use the tranny pump to get ALL the fluid exchanged (incl changing of the Tranny filter). It's a 2 job process (changing the filter/fluid + complete Flush). He also said that he could use Amsoil for an additional $100 charge instead of the GM tranny fluid. That's what they use on Corvettes.

I do agree doing such a service right before a long trip in Summer is "taking chances." However, I am also thinking "on the positive side" NEW Fluids might keep the car better lubricated and protect from the heat. It's like flipping a coin...

Probably the same for Diff fluid drain & fill also - GM vs Amsoil. Now Vs later...

The Coolant will be flushed and done by me at home - I think it's a simple task.

The oil was recently changed by me. So no rear tie end rods were greased.



I thought 50/50 was the standard. I bought 1 Jug of Dexcool + Distilled Water. That was my plan. Now I'm a bit confused - 70/30 ratio is best? (I'm assuming you're saying 70% Dexcool + 30% Water, means I gotta buy one more Jug of Dexcool)

Vette_Fan

I just did a small trip this weekend to San Francisco overnight. Going through Mill Valley today here's what my temps were -
Road conditions: Uphill / slow traffic (15 - 35 mph).
Outside temps: Nice sunny day 63* with the cool ocean breeze.
Tranny: in "D" & sometimes "S" paddle shifting 2nd/3rd gear. Tranny temps: 208.
Engine Temp: 225
Coolant: 210.

Speeds increase to 50-70 mph. Outside temps: 63-72*
Tranny: 203 - 198.

I need to keep a Notepad to really track the details

If these are my temps in San Francisco on a 63-72* day, I am worried what it's going to be when I go to Vegas where outside temps are 110.

Although GM may have designed these cars to run HOT , I'm trying to find out how to keep it COOL.


P.S: I had a 1999 C5 (A4). I had added a B&M tranny cooler, and a fan tune which helped improve temps by overall 10-15 degrees, or so I think...

HOXXOH

Run away from that dealer. He lied to you. There is no way you can empty all the fluid unless you pull out the torque converter. Removing and replacing the TC requires dropping the exhaust, rear suspension, and transmission, before you can get to the TC. That'd take several hours. Once you hear the word "flush" when talking about transmissions, you know it's not good. The owner's manual doesn't recommend a fluid change until 100K miles. Even then it's only drop the pan and change the filter, which only uses 6-7 quarts.

I'm sure Cherokee Nation meant 70% water and 30% Dexcool for better cooling, but 50-50 will work fine for you

Personally I think you're going overboard in preparation for such a short drive. Change the coolant, since you already bought it. It's only 541 miles, so just fill the gas tank and enjoy the drive.

Cherokee Nation

Correct HOXXOH...70% water and 30% Dexcool or somewhere in between.

jeffs64

Vette_Fan

I've been reading that in a few other places also on different car forums. 70/30 seems to be the "new" 50/50. BTW, since I'm in California, do I really need the 50/50? I understand water (Distilled) does better cooling than the Antifreeze/Coolant. Some guys even recommended using 70% (water) 30% (Coolant) + 1-2 bottles of Water Wetter in this combination, since WW works better with water. Anyone adding Redline's Water Wetter?

(Anyone using the "Super Flush" by Prestone while doing a Radiator Flush? I'm gonna tackle it today.)


Well, for one... You have a Z51, which has Oil, tranny and P/S coolers. The base model doesn't have those I think...

jeffs64

Vette_Fan

My understanding is water is the best thing for cooling. Antifreeze/Coolant does a job mainly for Antifreeze in cold weather, it does nothing to keep the temps down. 50/50 maybe the best bet for overall weather, but in hot conditions wouldn't it make sense to do 70/30?

Also, what's the take on flushing the radiator with Super Flush, while doing the Flush? Then fill it up with Dexcool + Distilled water?

jeffs64

Mike's LS3

Update: So I removed about a gallon of 50/50 coolant mix and added one bottle of Red Line water wetter and remainder distilled water. I drove in stop and go traffic with 79* weather, engine coolant temps seem to have dropped a few degrees and staying more stable. I need to do further testing in hotter weather and highway speeds to compare. My car is boosted and drive it only on weekends.

I do not have engine coolant issues, but just trying to keep coolants temps down so not to trigger any K.R. (knock retard).

Dewitts radiator, reprogramed fan, 160* T-stat and now one bottle of Red Line water wetter.

Stay tune for a later update.