In reply to Streetwiseguy :
"I don't care about the exhaust leak just fix the dashboard"
This happened a little while ago. Vehicle brought in for transmission not shifting. Engine oil pump was whining, oil looked like black mayonnaise, oil filter was collapsed (gotta love cartridge filters!), engine computer had a litany of codes all related to insufficient oil pressure... which forces the transmission to stay in one gear as a self protection scheme.
Customer was livid... he wanted the trans looked at and didn't care about the engine, and anyway he just changed the oil.
According to the instrument cluster, it had been 27,000mi since the last oil change.
Oddly enough, with fresh oil and filter, the engine made good oil pressure and the transmission worked properly...