In an impulse moment of OCD, I drained out the 2,500 mile Pennzoil Ultra and poured in 5 quarts of Mobil 1 0W-20 this weekend. As some with a Honda K24 know, the engine can be noisy when cold. Don't know whether it's piston slap, valvetrain, etc. I wanted to try the 0W-20 in it and I just didn't care to wait for another 3-4k miles. So far, the engine is significantly quieter on this oil. I don't get much, if any, tapping when cold (which sounded a lot like piston slap, but may not have been), and it's quieter when warmed up as well. Pennzoil oils have historically run the quietest in my vehicles, but with both Honda products now, Mobil's lubes seem to be the choice product for them.