Just picked up up a 2000 z28 (auto, 118k) from some friends. Grandma driven.

As it's gotten colder, I've noticed a knocking, kind of like a diesel, from the driver's side. Or the cold isn't an issue, I had the radio cranked until I got tired of the CD, which was also when it got cold here.

Conditions are:
[*]Noticable from 1,500 - 2,000 rpm
[*]Light load (tip-in) only
[*]No noise when reving in park
[*]Mostly when engine is cold, when at operating temp knock is gone or very very minor, again, 1,500 - 2,000 ish rpm only
[*]When it is cold outside
[*]No loss of performance/driveability
[*]Good oil pressure, never less than 40psi
[*]Has been run on 87 octane forever, just put first tank of 91 in it
[*]Had codes for O2 sensors, ran a scan tool which detected codes and cleared them. Haven't returned in 15 is starts.
[*]Has a fram oil filter.

Mostly highway miles.

Any advice would be appreciated.

 

Piston slap.
It's normal.
You ought to hear mine!

Ron

 

Its the fram.... not really but you should change out that filter. And I would run what the factory recommends for fuel. As far as the knock, change your oil...cut open fram filter abmnd check for any metal. No metal..probably just good ole piston slap

 

Any recommendation on the filter? Just not a Fram? I heard the Fram 49 was good. Thanks.

PS. The oil has looked good on the dip stick.

 

Its normal aluminum engine noise. Forget about.