jrhaines2

It's always good to change the fluid from break in.I thought you were talking about the quality of the GM fluid.

What differential fluid is used from the factory? I think it's almost unheard of a differential going bad is why I ask.

General Motors gives a shit.

I'm not sure about that.Like I said,I drive a lot of back dirt roads on hills that are rough and the AWD helps from keeping the rear from bouncing and losing traction and not sure how the auto 4wd would handle the situation but I will be fine with it.AWD would also be an advantage going around sharp corners as 4wd tends to try to push you straight.

Only after doing some research.

Well it's pretty apparent they are 2 different systems.I travel a lot of back roads and hilly gravel roads and in the winter the AWD handles those types of roads better but I can get by fine with the standard 4x4.

I'm not entirely sure of the operation and discussions where you learn are always a good thing in my book.

From Carfax. All-Wheel Drive Basics Let’s get a basic understanding of how all-wheel drive works before we dive into the configurations of this system. For a vehicle to have all-wheel drive, it has to be equipped with a center differential. A center differential is a set of gears that splits power from the transmission to the front and rear axles. Helping out the differential out are wheel sensors, which detect traction loss, wheel speed and other data points. Now let’s look at how all of these components work together. Let’s say you are stopped on a snowy road and you decide to its time to move. You press down on the accelerator and power begins flowing to the wheels, but one wheel is spinning in the snow without gaining any traction on the road. This is where all-wheel drive comes into play. Sensors detect the loss of traction and begin feeding information to the vehicle’s computer. From there, the computer will adjust the amount of power going to each wheel, sending more to the wheels with better grip to get the vehicle moving. All-Wheel Drive vs. Four-Wheel Drive All-wheel drive is often interchanged with four-wheel drive in advertising, which causes many people to think they are the same thing. However, there are some key differences between all- and four-wheel drive systems. One of the big differences is how often these systems are on. All-wheel drive is running all the time, varying the amount of power to each wheel. Traditional four-wheel drive systems in many vehicles are classified as part-time systems, which means the vehicle operates in rear-wheel drive until four-wheel drive is selected by the driver. You’ll find part-time four-wheel drive systems in many trucks and off-road SUVs. However, certain models built by automakers such as Jeep and Land Rover have full-time four-wheel drive systems that are always on. While all- and four-wheel drive systems both have front and rear differentials, four-wheel drive systems usually feature a transfer case instead of a center differential. This part has a number of gears encased in it that split power to the front and rear axles, providing both sets of wheels with maximum torque. Transfer cases also usually provide high- and low-range gearing. High range will allow you to drive at normal speeds, and is typically used for icy conditions or snow-covered roads. Using high range might also make sense on dirt roads, or in light off-road situations. Low-range gearing will limit your top speed, but it also provides a lot more power for more intense off-road conditions such as rock climbing, deep sand or muddy trails.

They were Yukons.I looked at a 15 and 16 and were both 4wd.

Yes my 07 has AWD and is always on and I was looking at 15's and newer and seen the selector.I had an 02 and 07 Denali with AWD and AWD was only available on the Denali version with no other options available as far as AWD or selectable 4WD.

An AWD system employs a front, rear and center differential to power all of the wheels. Sensors in those wheels take hundreds of readings per second. These sensors monitor each wheel's traction and the center differential increases and decreases power to each wheel as needed. This allows for fantastic control in all sorts of weather conditions and doesn't hinder your maneuverability. At low speeds, AWD isn't as robust, so don't expect that raw power you'd get from 4WD. The same goes for pure towing power, which is why you mainly see AWD systems on cars and crossovers, not big trucks and SUVs. Another difference between 4WD and AWD is that 4WD can be switched on and off. AWD is always on, so if you're seeking out top-tier fuel efficiency, then AWD might not be the best route to go. On the other hand, there are advantages to always having AWD engaged. AWD's ability to instantly adapt to changing road conditions, like ice and snow, without having to flip a switch takes human forgetfulness out of the equation. It's a much safer way to drive. I will also add that an AWD vehicle does not have low range.

Thanks for the reply but that is 4wd not to be confused with AWD.

Am going to trade up from my 07 Denali and it looks like AWD is no longer available.Was the change in 2015?