wet framerail

anyone know what could be the cause of this leak?
wet shows up on the driver frame rial inside the wheel well......
seems to be oil related? slick to touch. not sure if it is from master cylinder or turbo??

Is the truck puking coolant?

a couple things to check, turbo cross over tube seals, powersteering lines next to master cylinder, seals on glow plug connectors and valve cover gaskets.

ok, good items to check for......
truck recently was in dealer with cab off repair off exhaust leak. had 1 turbo replaced because exhaust bolts broke off in it. never leaked before, never smoked before.....now it smokes like a frieght train duuring and after regen....... 71k miles on it. while in dealer it had rad and hoses replaced as well. it is not puking coolant but does dip low in the bottle every now and then and needs some but doesnt leak.......
i stopped by the dealer and the tech looked under the hood for 1 second and said ---- maybe the u shaped turbo seal? book it in for service........