It could be that hydraulic lash-adjusters may be clogged up.
battery is dead
lights are on
The manual specifies only Subaru fluid. If this is not available Dexron III can be used until Subaru fluid is available. Noise and hard shifting will be the result.
It may be the heat shields on the exhaust system vibrating.
Worn engine parts. Most likely a rod bearing is worn.
It could be a sticking hydraulic lifter or valves that are slightly out of adjustment.
ticking sound from a wheel is usually a dry or worm wheel or axle bearing
the ticking noise is a small exhaust leak close to the exhaust headers or exhaust pipe near the engine.
A normal ticking is the fuel injectors opening and closing, a very loud ticking with bad mileage and poor performance may be a sticky lifter, aka hydraulic valve lash adjuster. If the latter try something like Marvel's Mystery Oil or another sticky lifter nostrum before launching into a difficuly and expensive replacement.
The ticking noise is the metal cooling.
The fuel injectors make the ticking noise you hear at startup, especially when the engine is cold (colder temperatures).
if ticking noise is in engine, u most likely have a worn hydraulic lifter. check oil for correct volume and viscocity