I don't get it...
.
I bought a new 2009 1-ton Duramax last November. I have taken it to the selling dealer for service since the day I took delivery.
At 10,000 miles, I switched to Rotella T-6 synthetic and an Amsoil, high-efficiency filter.
Yesterday, at 18K miles, I had it at the dealer for oil & filter (I brought my own T-6 oil and Amsoil filter) ... fuel filter... differential(s) drain and refill and tire rotation. (I intend to keep the truck for many years, so I pay close attention to servicing.)
I get it home and check the oil. Hmmmm. Looks pretty dirty for 200 miles. I crawl underneath and check the oil filter. My Amsoil filter? Nope... not even a "Genuine GM" filter. The dealer installed a Quaker State oil filter and God only knows what kind of oil he dumped-in.
I call my "service consultant" at the dealership... (He was on vacation yesterday, so I worked with someone else.) I asked him why they install cheapo filters.
He was honest in his response... "It's cheaper." he said... "Most customers want a low-cost oil change, so we use the Quaker State filter. The oil was Rotella non-synthetic."
Lesson learned for me... From now on, double-check that they are using my oil and filter.