Unless the SRT6 differs from the Stock or Limited versions, these engines hold 8.5 quarts with a new filter installed. If the dealer put only 8.0 quarts in, then you are shy half a quart.

ALWAYS double check the oil level when you let ANY shop change the oil for you.

That is probably the cause. HI would indicate that the oil has been overfilled and is showing excessive pressure when the engine is at high RPM (Revolutions Per Minute).

Hope that helps. Cheers!