I just bought a 1997 F-150 Lariat looks really nice, the previous owner says that it does not burn any oil. However, I noticed that the bottom of the truck between the transmission and engine is wet from oil and the transmission pan is wet.

Is the normal for American Cars? I had the same thing with my 1977 Chevorolet truck.

 

Sounds like it might be the rear main gasket, how many miles are on the truck?
Oh, and welcome to the board, you will find a lot of good information on this site as well.

 

The truck as 60k miles, how much will it cost to replace that gasket?

 

How difficult is it to replace the rear gasket? Can I do this myself?

 

I would have to say that it is probably best if a mechanic does the repair of the rear main gasket, because there can be a lot of work involved with it. I don't know about on the F150s, but I know on my Jeep, it would have taken 13 hours to fix it, and at $75 per hour labor, I could add a lot of $.99 quarts of oil, bad part, the gasket would have only cost me $15.00....So I just let it go. That is just me. You could probably do it if you have all the right tools, and are very mechanically inclined.
Have a mechanic look at it, they could do a "dye" test, to trace where the oil is coming from, they dump a dye in your engine (non-harmful) and you drive it for a while, and then bring it in, and they use a light to track it down, and then they can go from there, and let you know what it is that is leaking. It could be something as simple as a valve cover gasket. Worse case is the rear-main, or the head gasket.

 

Before you do anything, make sure the oil filter is on correctly, and that it didn't split. That's what happened to me.

 

Ifs its the rear mailn seal-then its about 4-5 hours book time...If its the oil pan gasket, thens its about 3-4 hrs labor...

Big jobs --both of them...

 

Before you do anything I would clean the area w/ a degreaser. It could just be a loose oil filter or plug (or maybe it was loose at one time) like FordFaithful said. Also, what kind of oil are you running? When I ran Mobil 1 it leaked from the plug until I tightned the hell out of it a few times, but now I just run castrol 10W30 in my 97 4.6

 

Before doing anything drastic, clean it up and keep an eye on it like others have said. A mechanic (if you want to call him that - a whole nother story) diagnosed a bad rear main. After cleaning it up and keeping an eye on things, it was from oil blowby from a loose drain pan plug. I could have been taken for quite a ride!

 

You guys bring up some good points--make sure and dianose it before any work is done...

They have dye that you can add and use an UV light to determine where it came from....

A car wash is a good place to spray down the underside of the engine...

If its a rear main--you will know...

If you have advanced mechanic skills you could do this job, it will take a while although...