Thanks guys, Larry what is CI4 oil? Also today I drove the burban, towed the boat and the noise kept coming back at idle or close to it. I also noticed the oil pressure went down to 20 on an ocassion at ilde after getting of the freeway. Most of the time the pressure was at 30 to 40 at idle and 60 on the freeway. Not sure if it makes any difference for diagnosing.
I will change the oil tomorrow but I need to understand what CI4 is.
