GM 6.0 Piston Slap, what oil?

[Gyro Gearloose]

I had an 01 Yukon with the 5.3 that developed increasingly louder cold engine knocking noises until we traded at 215K. I tried multiple brands of 5W30, dino and synthetic, and even 10W30. Nothing made any difference in the noise that I could tell. We sent it to it's next owner running great once it had a half a mile to warm up using only about a quart of oil every 2500 miles.

 

[hawkdriver]

I briefly owned a 00 Sierra 4.8L, bought used with ~35k miles. Found out it had piston slap that winter. Tried a few different oil brands and grades but nothing helped. Local mechanic said it might run for +100k...or it might not. Traded it the next summer at the same dealership that sold it.

 

[burbguy82]

I am not sure that oil will help the situation, but I would use a 0w40, Mobil 1 0w40 is pretty serious stuff for the price at Walmart.

 

[DGXR]

I would start with 10w-30, if your winter temps allow 10w. This worked in my Tacoma which had piston slap only on cold starts under 25F.

 

[ka9mnx]

I had piston slap noise in my F150 when I went with 5w-20 Ford spec'd with a TSB. Immediately went back to the original OEM spec grade and haven't had the noise since changing.

 

[demarpaint]

delete.

 

[PontiacHO]

Piston slap in the early 2000s GM LS engines was happening right off the showroom floor. If it has made it this long carry on with what got you there. Is gas mileage more important than engine longevity though?