http://dspace.mit.edu/bitstream/handle/1721.1/12156/30012843.pdf?sequence=1
It's an old MIT dissertation paper, but a great source of info. 10W30 weight oil was the best for damping the noise and vibrations, while 5W20 weight was the worst.
This agrees with the epidemic of piston slap in 2006-2010 toyotas when 5W20 oils were implemented.
This also agrees with my experience when piston slap-like noise showed up in my RAV4 when dealer filled it with 5W20 instead of 5W30 that was specified.
Unfortunately, going back to 5W30, 10W30, and now 0W30 GC didn't reverse my noise, so I'm not 100% positive it is a piston slap.
It's an old MIT dissertation paper, but a great source of info. 10W30 weight oil was the best for damping the noise and vibrations, while 5W20 weight was the worst.
This agrees with the epidemic of piston slap in 2006-2010 toyotas when 5W20 oils were implemented.
This also agrees with my experience when piston slap-like noise showed up in my RAV4 when dealer filled it with 5W20 instead of 5W30 that was specified.
Unfortunately, going back to 5W30, 10W30, and now 0W30 GC didn't reverse my noise, so I'm not 100% positive it is a piston slap.