Hi, guys.
I put K&N oil filter on my wrx 6000km ago, yesterday some burning smell came out the engine bay, so I drove to city subaru to check it. Oil filter cracked!!!

Thats not the only wired thing. I told them I used redline 5w30 before I let them check the car. After inspection, they said oil filter need to be changed, which is perfectly fine, then I was told they only have mobile super semisyn, I thought, ok, I will switch back to redline later(this week is my exam week). But after I drove home, I pull out the dip stick, the oil is very dark!!! Check the receipt, they only use 1L of mobile super, and it is 10W40, which I think they reused my redline and toped it up with mixed-grade and mixed-brand oil.

Are they supposed to do that? Will the oil damage my engine? Do I need to change the oil asap?

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MY08 STI 422whp at 1.5bar on E85, built by Diversion Garage, assembled and tuned by EvoR

Update from new owner: 375whp at 1.4bar on 98, at Tokyo Motorsport