I just bought a 93 f150 exactly one week ago with the 4.9 with 53,000 original miles thinking it would be a problem free truck. boy was i so wrong. so far i have had heat problems and windshield washer fluid problems( maybe due to cold weather), bad check valve in front tank. now i have an oil leaking problem. Is this a pan gasket or rear main? here are some pics

 

looks like the rear main but I beleive you have to drop the pan to change it so I would change them both...how much oil is it using

 

i just noticed it last night and put 2 quarts in it.i have driven it about 250miles since i have bought it.. thought it might be the pan gasket since the whole drivers side of the pan is oil soaked around where the pan meets the engine. any info or advice will be appreciated.

 

An oil leak on a vehicle is like a cut on the head. They look tramatic, but end up being something small. Take the easy route first, through a wrench on all the pan bolts and make sure they're tight, as well as the filter. If you've got a breather, make sure it's not gunked up and blowing oil back through the dip stick.

 

i had a leaking tranny pan gasket and i tightened the bolts and it never dripped again. you can also try adding gasket sealant. or try using thicker oil. it'll leak less with thicker oil and also prevent wear on the rings and bearings which is crucial on these old inline 6s. if i was you i'd get under the engine with some engine bright and clean it up real good. then start it up and let it sit for an hour or so and turn it off and see if you can see where its starting to get dirty. that should help you narrow it down. good luck

 

All these tips might work. Also at oil change, with maybe a thicker oil, put a quart of BARS LEAKS in it. Autozone has it. It is for rear mains that aren't TOO FAR shot. And by the way, GET RID of that Firestone oil filter!!!!! Motorcraft plugs and filters.