So i finally decided to go to the stealership for a tune up. I hit 4 years on my ride and only 22,000 miles on but i figured that 4 years on the same plugs, time for new ones. Anyways, ive been running royal purple for the last 3 years and when i brought it in, i said to skip the oil change. Of course when i go to pick it up, they changed the oil and put in house brand quaker state oil. How bad is this for my motor because ive heard many stories saying it is bad, and others saying just wait till the next change and go back to royal purple. I wanna see what the opinions are from my fellow owners. Thanks.