Originally Posted by SignOfZeta
It'* perfectly normal for an engine to consume oil. Even when new, a 3800 Series II is rated to burn about half a quart every 3,000 miles.
I can't imagine a 2005 GXP has too many miles on it, but if it does, you may want to look into replacing the piston rings or valve seals whenever it'* convenient for you. Not sure if either are known problems with aging Northstars; ask one of the Northstar gurus.
Thats what really throws me off, I have a 1997 SSE with 143,000 on the 3800 series 2 in it and I run that to the full 15,000 miles and it doesnt change at all on the dipstick, same with my 1992 SE it doesnt move a mark on the dipstick for the 15K? I have owned four bonnevilles and the GXP is the only one that uses or loses oil?