Irritating Rattling/Grinding Noises Coming From the Engine

[el cobra clutch]

Let me first start by saying that this is not my first encounter with this issue. A little over two months ago in early February, I noticed an odd rattling/grinding noise coming from the engine each time I started my 2012 Buick Verano. Since it typically went away after 1-2 seconds, I thought nothing of it and dismissed it, attributing it to what I assumed was normal behavior for 4 cylinder engine during winter time. After a week passed, I noticed that the noise persisted and now appeared periodically while I was driving, specifically when in low RPM (under 2000) while accelerating. I found this downright annoying and irritating, as it was starting to impact the car's performance. At the time I had 48K miles on it and was fast approaching the end of my 50K Bumper to Bumper warranty (I bought the car new in 2012). Since I was due for an oil change, I took it into the Buick/GM dealership here in Omaha, NE and had them look into the issue (along with changing the oil). When they called me to tell me it was done, I asked what was causing the noise problems. They told me that the root cause was the Belt Tensioner was shot and was perpetuating the problem. Since the vehicle was still under warranty (just barely), the cost and labor for the Belt Tensioner (and Drive Belt) replacement was all covered by Buick. I paid for the oil change, thanked them and departed. As I drove off, the car purred just like it did the day I drove it off the lot new back in '12. Everything was going to be alright, I told myself. Fast forward to this week: April 18, 2016. I currently have 52K miles on the car (I travel...a lot). When I started the car on a mild spring Monday morning, to my shock I was greeted by that all too familiar rattling/rough engine sound for a few seconds. After driving to and from work, I observed that the sound only appeared upon starting the car. Yesterday and today were different stories. The noises not only appeared on cue per their usual , but persisted yet again when I accelerated (RPM in between 1000-2000). Now I'm not due for the next oil change until 53k miles, according to the sticker that Buick put there after changing it back on 02/10/16. But just to be sure it wasn't oil related, I scrolled through and checked the oil level screen which displayed as 67% remaining. I find it hard to believe that 67% oil level would be causing the exact same irritating noises and sounds that a defective Belt Tensioner and Belt Drive did two months ago. This is beyond irritating. Before I take the car back into them (again), I'd like to know if anyone on here has also had the displeasure of having to deal with this same issue? Any ideas?

[LCromwell]

First off it is not at 67% oil level its how much time is left on the oil in the engine. Second I believe there is a 90 day if not one year on repaired parts call them.