What is this and why it is leaking

My truck has been sitting for a couple of weeks and left a large pool of "oil" on the floor 24" x 24". I am not at all a car person and was hoping to get some insight before I take it into the shop.
Its a 2002 Tundra limited with Auto trans any help from experts here would be great.

 

Any oil changes recently that drain plug wasn't tight enough? Can't tell by pic where is that on the vehicle.

 

Actually oil change was the week before it was parked, had not thought about that until you reminded me because my brother took it to the local drive thru shop. How tight is tight for the plug, I don't want to over tighten ? If it's tight what are other sources?

 

X2, hard to tell exactly what we're looking at. Can you take a couple more pics? Like COMiamiFan asked, any service prior to the truck sitting?

 

Is that the transfer case?

 

If that is the plug in the middle it the washer supposed to be nice and flush. Could they have cross-thread the plug. Remember I am NOT a car
guy at all!

 

I just looked on line to see what a transfer case looks like and yes that is what it looks like.

 

The bolt on the left seems to be where the oil is leaking. The angle on the first picture is a better angle but it's too low res, if you have a higher resolution of that one, post it so we can see the details. Quick oil change places are notorious for loosening things, or outright breaking them, so they can repair them later. They also use impact wrenches on drain plugs. On a high volume day, cross threading plugs is fairly common. Assuming, of course, that they get it even close to tight and it doesn't fall out later. In case you haven't noticed, I'm not a fan of quick oil change places.

 

I thought that looked like the transfer case. If your truck went in for an oil change they should NOT have touched the t case drain bolt. It does look like the washer is boogered up. That drain bolt should be tightened to 27 ft/lbs and if it was removed the washer should have been replaced with a new aluminum crush washer. Can you tell from the fluid on your floor if it's brownish like motor oil or grey like gear lube? Also, if it's gear lube it will have a fairly strong odor.

 

The fluid in the pic does look like motor oil but it looks residual. Hard to tell where it came from. Check your oil pan (smooth black pan towards the front of the motor). If the drain plug in the oil pan is the problem everything around it should probably be covered in oil. It very possible that they stripped the drain plug. That plug should be tightened to 19 ft/lbs and as Randy Morton said, a lot of quick change places use an impact which is very unnecessary.

 

OK per Duece292 I looked for the oil pan and it looks dry, this is directly rear of the pan. the fluid is golden in color, I don't know the difference in smell between the two so I can't help in that regard.

 

Looks like your transfer case fill plug is the culprit. The washer looks bent up underneath it, one should be able to remove the plug (bolt) and insert a new washer then torque it down to around 30 ft/lbs. Also, you may want to consider putting some fresh transfer case fluid (Differential fluid, specs should be in the manual or Google) in there and filling it up.
I am not sure how or why this would have been removed for an oil change...
Unless the "shop technician" did not know what he was doing. Or... he may have been checking the condition of your fluids, and did not torque it down correctly (this is the most likely situation).

In either case it is not a major problem as long as you ensure the fluid is full and fix the leak... Easy Cheap fix

 

Next, put a piece of cardboard under the truck and look for the next drop. You should be able to track back from there. You might put a wrench on that bolt and see if it's tight.

 

Also it is difficult to ascertain what component this is because we do not have a wider view of the components around it. if we had that it would be a great help!

 

Golden color certainly sounds like motor oil. I would check the oil level. If the level is good it's very possible that they just made a mess of your truck while changing the oil and didn't bother to clean it up (not the first time it's happened). A short drive would have been enough to blow any oil back onto everything behind the oil pan. With the truck sitting the oil would have ample time to drip onto the floor and oil does tend to spread a bit making it look worse than it might actually be. If you're still in doubt though, take it to a qualified shop and have them take a look.

 

Golden oil could also be Differential fluid/T-case fluid.

 

Thanks for all you help everyone. Below is a web image of a Toyota transfer case for those that want to match up the perspective. Why the tech was there I don't know and it was brother that took it in for the oil change to thank me for letting me loan him my truck .... Next time I will suggest Beer

 

I wouldn't be surprised if the idiots at the lube shop drained your transfer case and filled it with motor oil. The drain plug definitely looks disturbed. Almost seems like a good idea to take it somewhere and have the transfer case and motor oil changed again. (A reputable shop) Since you're not a car guy. While you're at it change the front differential fluid and rear differential fluid.

 

Like someone else suggested put a piece of cardboard down and see where the next drip is. I know quick lube places have idiots there and have a bad wrap but I highly doubt they changes your t case fluid instead of your motor oil. Now you said a 2 foot round puddle(24") the pics you showed doesn't look like something that could make that big of puddle. Did you clean that area up at all before the pics? This is the important part. Verify for sure where the fluid is coming from. Like others have said they could have made a mess and gravity pulled it out when Parkes. Or drain bolt leaking. All I know is if I suspected oil in my t case I would not be driving. You can take the t case plug out stick your finger in there and feel the oil, then compare it to the oil on your motor dipstick. You should be able to notice a very big difference between the two