I had a bottle of Amsoil engine flush laying around so I decided to use it. Ran it for 12 minutes @ about 1,800-2,000 rpms. I then filled back up with Mobil 1 0w-30. Super smooth as always. No noise issues at all. Feels like all the other 20 grade oils I've used. Probably because of the low HT/HS of 2.99. I also noticed M1 0w30 has more moly than other grades of M1 @ 100ppm.