I bought this black beauty in March 2012 and it had this issue on second day, oil level was very high almost an inch or more over the full mark. Used car service manager said that was ok on these models as they need more oil and asked me if I knew how to check oil. So i passed it off as I have built engines in the past, samll blocks with superchargers even, and had no problems. So I cahnged the oil myself, calls for 6 quarts, i repalced filter-added 5 quarts and started it up(i always fill filter first) then shut down for 5 minutes roughly and topped off to full with about 3/4 quart so all together=filter plus 5.75 quarts of oil.....
next day checked fine,
next week got home from work went in and changed clothes went back out checked oil-10 minutes and well above the full mark by at least the same area as the hatched fill zone.
Went and asked service manager again and they said it was not uncommon for oil levels to fluctuate----didn't know i had a oil producer under me??!!

so went 2500 miles and changed to full synthetic- same procedure, filled filter first and added remainder of 5 quart tank and cranked up. Waited 5-10 minutes and added what would be 1/2-3/4 quart again to reach full mark. all good for a few days then it jumped immediately back up to an inch or more over full.

never have i lost any coolant fron the system that i had to replace.

i have only ventured to add a Volant cold air intake and a TB spacer, accele coils and wires and new plugs. I have gained 3+ mpg doing this though, until yesterday.

Carry a load of goods from old home to new home engine stumbled lost power and then regained only with severe rattling-clanging-pinging etc and also noticed a drastic drop in oil pressure from the norm of 60+ to less than 40 psi.
Hobbling to nearest parking point it became louder and while watching gauges i saw the oil pressure gauge drop to "0" and i immediately put in neutral and killed ignition and called AAA for tow. I did scan and came up with P0421 low oil pressure and P0461 low voltage sensed.

Dealership has it now and conversing with GM Tech pool to figure something out, they did ofer that something was bad wrong but could not figure it out specifically.

Help anyone.

Please...

 

Hope gm doesn't hold it against you for all the changes you done..

 

I dont know what to tell you except that is complete BULLS**t. The dealership should have taken care of it right off the bat and not keep telling you what you should do. I would be very disappointed in chevy if they didn't honor a mistake in their product. I have a 99 and yes it takes 6 quarts, I usually put about 5 and half because thats where its right in the middle of low and high but anyways they should take care of it. Don't know if this helped but I had to give a piece of my mind on that.

 

Your dealer is an idiot.Oil levels should never be above the full hash mark.

Sounds like the oil pump pressure relief valve is malfunctioning.
Not too common on LS engines but not too rare either.

Upgrade to an aftermarket Oil pump.

 

This guy must have come out of used car sales. Think about it, if that engine needed "more oil" the dipstck would match the pan, and full would be full as required.