Has any one used or considered using the Q racing oil from Quaker state? I was looking at the 15W50 and the 17.5W35. I am looking for something with sufficient zinc, ect. for flat tappet cams. Iv'e also heard of people using the Shell rotella 15W40 or the adding a bottle of GM EOS to every oil change. I know there are a lot of posts on here about oil for flat tappet cams, but I was just seeing if anyone has an opinion on the Q racing oils and if they have the additives for flat tappet cams....