oil presure
looking to buy a 2015 duramax in a 3500 chevy silverodo with the z71 package at it s ltz .. took it for a test drive and it had loose steering and the oil preasure just starting and going down the road was at 60 lbs but, when i stopped at the lights it would drop to 40 .. not used to that i have a 5.3 gas it holds 60 all the time.. is this like the dealer says , normal ..He took it in garage and had to replace the parts to the steering box..