Mobil 1 made my Civic engine sound noisy, while I'm sure it was well protected by Mobil 1, the sound (noise) was unnerving. I thought it would go away, so I left in in for 1,000 miles. The noise never went away with Mobil 1 5w30. Switched to Amsoil 0W-30, engine runs smoothly and more importantly (to me) quietly.