Engine Knocks at cold start
 

My engine used to knock slightly at a cold start. as the temp is going down i notice it more. any help? like adding a thicker oil or something. Using 5w-30 high mileage

you want thinner so your oil gets circulated easier/faster in the colder weather

u sure its not piston slap? 60 degree v6s are known for their piston slap

More than likely its piston slap. My dads 3100 Malibu did it in cold all the time. He also had a LS1 Camaro that sounded like a diesel in the cold because of piston slap.

Anything I can do for the piston slap then?

& I thought you'd add thicker oil?.. The thinner it is, the easier it pushes through & slaps. Right?

The noise comes from the bottom of my engine I think. Oil pan area

You could try adding some lucas oil additive, that stuff is pretty thick, might quiet it down a little.

Piston Slap is a very typical problem with our motors. The piston skirts are just too short. Mine does the same thing. I have tried 5w30, 0w30, and 10w30. All with the same result. What GM told me is, don't worry about it. They said it is just how they are designed. You could go buy a brand new motor, and by 25,000 miles into it, it is going to do the same thing. Thank you GM Design Team. Don't worry about it. Once it warms up, it's all good!

IIRC I read something about the pistons being a little undersized, so when the engine warms up the pistons expand and there's no more piston slap. Just don't let the engine RPMs get too high just after a cold start.

yeah its comepletly normal.

Mine sounds like a damm diesel on cold start up, once its warm it sounds normal

but mine idles around to 1500 on a cold start...

Thats fine. Hes saying dont be redlining the engine when its knocking. Or any cold engine for that matter.

Over 200,000 miles on mine and its been doing it for a couple of years. Goes away 90% when it warms up. :rolleyes2: