Oil leak, AT oil temp light

Drove the truck back from Albert Pike in Arkansas yesterday morning. Drove around 75 miles per hour for about an hour on the interstate. When I pulled up at the bottom of the off ramp, my AT oil temp light came on. I was still around 12 miles from home, so I drove on. After a couple of minutes the light went off. It came on once more at a stop light, and then did not come on again. When I got home I looked under the truck and saw what I believe is oil on the front of the transmission pan. I just changed the oil and filter about 2000 miles ago. I'm hoping this is the valve cover gasket which I know needs changing, but have been putting off. My fear is it's something worse (rear main seal, head gasket, etc). The truck has about 289,000 miles and runs great. How can I confirm where this oil is coming from since I can't see all the way up the back side of the engine? I'll take some pics when I am able if that helps.

 

Heat soaked engines do all manor of strange things .

Clean things best you can keep an eye on fluid levels

 

Clean and monitor fluid like mentioned. Carry 2 extra quarts with you just Incase. How about that crush washer? New or reuse the old? Check the torque on the valve cover and tighten if necessary. My valve cover began to leak. 2 bolts toward the firewall were lose. Is the fluid brown or red? That definitely helps narrow it down

 

New crush washer when oil changed which was only about 3 weeks ago. Drove it to Albuquerque and back with no noticeable issues. I tightened the valve cover bolts (that I could reach) about 9 months ago. The fluid is brown and I'm pretty sure it's oil. Guess it could be old transmission fluid though. Does it have a different smell to it than motor oil? I didn't have much time to investigate when I got home yesterday, and I'm back at work today. Going to have to let it sit until I can do some deeper digging. Luckily I have another vehicle.

 

Checked the oil fill cap last nite and looks normal (no pink milkshake). Oil level is at the top of it's range just like after I changed it. Transmission fluid level is in range for the engine being cold. Radiator fluid looks normal. I guess a little oil can look like a lot of oil when it spreads around. Ordering all the stuff to do valve cover gaskets today. Also doing spark plugs, wires, and tube seals, throttle body and IAC cleaning and gaskets, plenum gaskets, half moon and cam plugs, and PCV valve and grommet. Am I missing anything I should be doing while the vale covers are off? While I'm in there, I'm going to replace the timing belt and water pump. Might as well put in the upgraded alternator and wiring set I just got from @TheMachinist also. I've watched the @Timmah! videos on the valve covers and he makes it look pretty easy. Hoping to get it all knocked out in a 3 day weekend. And hoping it solves my oil leak problem.