I just hit 1K miles on my '09 AWD CTS 3.6 Di and decided it was time to change the Oil & Filter as this car will have to last me for a while. The previous post(s) were of some help as far as removing the upper engine shroud but the AWD has a different lower panel under the engine and the drain plug is not in the same location. So the proceedure starts similary when taking the upper engine shroud off you simply take out the oil filler cap and lift up on the left side of the shroud to overcome the pin/grommet attachment and then slide forward to remove. The lower engine cover has four 10mm bolts and two integral split plugs that snap into a receptacle. I used two small screw drivers to push on either side but I think the other side came right out on it's own once the weight of the cover was on it. Unfortunately I took the car off of the lift before I realized I hadn't taken a picture of the lower shroud on the car but the attached pictures should give anyone the general idea. The oil plug location was a little perplexing as at first one could conclude that it is the internal hex plug that is the Getrag transfer case drain. After checking on the forum to see if anything pointed to where the plug was, I decided it had to be the bolt with an integral washer, which it was. Unfortunately I didn't have a new flat washer gasket but it appeared OK and it didn't leak after I started the engine. I'll have to change that seal the next time around. All in all not too bad of a job especially with a lift but one I'm glad I did at 1k miles as the oil was darker than I expected. I used a Napa Gold filter P/N 7090. Normally I fill the filter with oil but I simply snapped the filter into the cover housing and tightened it up before I thought about the possibilty of pushing the filter down into the housing first and filling the housing with oil prior to putting the cover on. I'll try that next time but there was no audible top end noise on start-up and the oil pressure came up quick. It took 6 quarts of Mobil 1 5W-30 and it still could use another 1/2 quart to get it full. So for what it is worth that was my experience with an AWD 3.6L '09 CTS.