I've had my '98 F150 since early Y2K and have noticed a light brown oil at the filler port ever since owning it. The truck had 28,000 miles on it when bought and now is around 121,000. Today, while replacing 2 tires I had the oil changed and was watching it drain out. No stirations in the used oil. The mechanic lowered the truck down to fill the crankcase and pointed the light brown oil out to me, I told him it's always been that way. He said I may want to do a compression check and I told him these '98 engines have a history of failed gaskets. The engine idles smooth and I'm not beyond pushing it when traffic is light. It runs fine. What do you Blue Oval loyals think?

 

If it is what I am imagining, mine has the same thin film of oil on the bottom of the fill port cap. It has always had the oil film.
At 150,000 I'm guessing it's not anything to worry about.

 

Thanks Brian. It runs really good and like yours, it's always been there. I ain't losing no sleep over it.

 

if it was a blowed head gasket the oil cap would probably have white foam on it. and if you put all of those miles on it i dont think you have to worry about it being a blown head gasket.

later