[blue62]

Looks like oil fog and road grit. Doesn't look as if the engine bay has ever been cleaned.
have it steam cleaned or degrease it with a good engine degreaser.
Take your time get it as clean as you can.
Every where you can. above and below.
Once it is clean you will be able to tell if and where you have oil leaks.
A dirty engine bay just complicates any issues you may have.
A clean engine bay makes things easier to work on and easier to see issues.

I spent two days cleaning mine when I bought it with 45000 miles.
Now when I remove the engine cover I know in seconds if there is an oil leak.