Loud Engine Knock during Cold Starting

[Turk]

Howdy,

I have a 2003 GMC Sierra, 5.3l with 96k on it.

I run 5-30 Amsoil, change it & the Wix/NAPA Gold every 6-8k.

During cold starts (0-20 below), the engine knocks loud for about 30 seconds, then goes away.

Engine runs & sounds great after that...

Any idea what it could be...?

Anything I could add to the Gas or Oil to reduce that...?

 

[Turk]

Oh yea, I better clear this one up - it is "Not" the Piston Slap issue. My old 5.3 had the piston slap.

This is a Knock - then it mysteriously goes away after 30 seconds...

 

[unDummy]

Use a different oil filter at your next change. And, make sure oil level is topped off.

 

[JTK]

The 4.3L in my 1998 K1500 had a ~30sec cold startup knock like that. Piston slap can sound different from engine/engine. AFAIK, that truck is still on the road and doing fine.

Joel

 

[swalve]

Hydraulic lifters tapping from lack of oil?

 

[Turk]

I'm kinda thinking that it is a lack of oil also.

Just changed the Amsoil & from a NAPA Gold to a Wix - it did it on both the old and new.

You would think that the Amsoil should get the Oil around the engine as fast as any other oil, right...???

 

[harry j]

Try an Amsoil Eao filter next oil change, it cleared my noisy start ups.