Improper engine break in.

Just changed the oil and filter in the 2001 Jeep Cherokee. Valvoline VR1 SAE 30, still runs like new. Same for the 96 ACR Neon, same for the 66 Formula S. I ask for it and my parts store gets it for me. Brad Penn is great oil. If you want to run multi grade, I go with 10-30 in the 2009 Challenger.