Hi, I need to replace the engine on my Evo X and sourced a replacement that was supposed to only have 37K miles on it, and compression of ~140 across all cylinders.

1. First photo is my current engine with 48K miles on it and only issue is bad compression on cylinder #2 (~70PSI vs. ~115PSI others).
2. Second picture is the replacement engine I purchased. What would cause that kind of staining on the bottom end (under oil pan), and is that a concern for the longevity of this engine??

Current engine with 48K miles, only issue is low compression on cylinder #2 (70psi vs. ~115psi for others)

Replacement engine that supposedly only has 37K miles, and ~140psi across all cylinders. Why the staining!?

I dont see any pictures on your post. You need to attach them by uploading them to the website.

I can see the pictures.

Huge difference in color I am not sure but very curious as well !

That discolor is due to lack of changing the oil on time. Also could be cause by using the wrong type of oil.

There is not much information to be found unless you test it for compression or do a leak down test. Oil staining is a common thing and doesnt affect the engine health.

Looks high mileage but it isn't, means oil changes weren't done on time. And compression is low. Rebuild it.

The coloring is concerning, bad oil maintenance = higher chance of component wear?