slaytop,
"Innocence" or "ignorance" or "I don't care." Sometimes I wonder. On my round trip from CA to PA, I had Four Seasons Chevrolet, in Tuscola, IL, change oil (Synthetic Mobile 1). As usual, I explained what I needed, the oil changer guy runs down to the local auto parts store for the oil. Proudly, he informed me he used 15W50W mobile 1 for Duramax diesels. Upon checking on-line, he was wrong, this oil is rated for high performance gas engines and older cars and does not meet CH-4, CI-4, or CJ-4 requirements for diesels.
I only paid $144.00 for the wrong oil which included about $2.00 for window washer fluid. Fortunately, I am staying 7 miles away and I'll be heading up today for another oil change within 2 weeks.
Scary...........when you can't depend on the trained professionals.
Forrest