Loud Knocking in Winter

Sounds like piston slap/knock from piston wear on the bore and the piston rattling around until it warms up and swells some. It can get really loud on a very cold morning and the more power applied the worse it is until it heat up though it might never go away 100%. It is not as bad as it sounds if it is piston slap/knock and may run for several more years and it will not suddenly blow up either. What year vehical and engine is it? We at not talking about a early GM 5.3 are we?

No it's the V6 4.3 Vortec engine... I didn't think it was a big deal because it only occurs in the winter, but I wanted to be sure...

Thanks for the insight!

Try any of the following to see if it/they work:

-- use a less viscous oil

-- use a synthetic oil

-- install an oil pan heater

-- install an engine block heater

a big deal

sure...