02 Legacy Help!: piston slap or rod knock? Wedding coming up!

[Ludwiggramsci]

I have 2002 Subaru Legacy L Wagon with 146,000 miles. The engine always has made a chugging/knocking noise since I bought it used 5 years ago. Most recently 2 mechanics told me that the engine is knocking and will die imminently. It has always made noise at start and lower RPMs but goes away at highway speeds. I am best man in a wedding that is a 5 hour drive and I am trying to figure out if the noise is in fact rod knocking or the less problematic piston slap. Here is a video of the sound at cold start:

Thank you in advance--I want to be sure to make this wedding! Should I rent a car or can I drive this Subie?

 

[Zubumafu]

I have 2002 Subaru Legacy L Wagon with 146,000 miles. The engine always has made a chugging/knocking noise since I bought it used 5 years ago. Most recently 2 mechanics told me that the engine is knocking and will die imminently. It has always made noise at start and lower RPMs but goes away at highway speeds. I am best man in a wedding that is a 5 hour drive and I am trying to figure out if the noise is in fact rod knocking or the less problematic piston slap. Here is a video of the sound at cold start:

Thank you in advance--I want to be sure to make this wedding! Should I rent a car or can I drive this Subie?

I hate to say it but that sounds like it could be a loose valve near the piston