What is this?

I think this is the underside of my transmission (auto). It is sticky but looks kind of oily (closest to the pan). What is it? What is that plastic looking thing as well?

 

plastic thing is cap to remove to access 2 of the bolts for the sub oil pan. Could be oil or trans fluid but honestly doesn't look like something id be over concerned about , just keep an eye on it , if u have solid drops then you will see whether its oil or trans fluid and determine if its a substantial enough leak to repair at that time.

 

It could be a rear main seal weeping or the transmission input shaft seal weeping. Doesn't look to serious at the moment. Clean it up and keep an eye on it.

 

check you driveway for oil spots and see what color. If black or brown, you have a rear main seal leak. If dark red or maroon, you have a transmission shaft seal leak. the rubber thing, is an inspection point to check flywheel condition; you wouldn't be able to stick any kind of tool thru it.

 

My skid plate would be in the way of a noticeable leak on the floor. What's odd is it has the consistency of like a deteriorating or overheating adhesive due to how sticky it is. Do any fluids on our truck get tacky in any situation? I could probably stick something to this.

Those referencing seals. Attached is a closer image. I'm not sure a seal could affect this area?

 

Grease that spun off the driveshaft and got smeared around?

 

I like this answer as its least concerning and makes the most sense. The residual spot doesn't feel "fresh" but the spin off onto this area would be kind of odd.

Those that have removed the plastic cover. Is there any real possible leak source on the other side? Can I just pop it off with a flat head and pop it back in? Is it held in by adhesive?

 

like I said, it is just a "window" to look inside, the rubber thing you are talking about, is nothing but a dust cover sort of thing. This is common on all A/T vehicles. If you remove it, all you are going to see, is the flywheel and maybe the transmission shaft, but I doubt it cause the converter pretty much blocks the view of everything else. back to the properties of your leak, if you ever had a vehicle leak engine oil on the driveway, you will notice that as the oil ages uninterrupted, it becomes thicker like molasses. That is because it gets mixed with dust, like in the picture. If you could see thru that window on the engine block side, you would see the crank shaft sticking out and the flywheel attached to it. Around that shaft, there is a rubber seal that keeps the oil IN the engine block. As the rubber deteriorates, oil starts to ooze thru it( since it is not presurized on that area). That is the reason it takes many weeks or even months for the oil to make it all the way out the bottom of the tranny and it is not until it saturizes or the rubber wears even more, that is actually starts to slowly trickle onto your driveway or parking spot.

 

I'm only at 100,000 miles so it's kind of disappointing but like some said I guess it doesn't look too concerning.

Update: it cleaned up nicely with a wet paper towel so maybe it wasn't oil or ATF? Only time will tell...