I was a salesman at a GM dealership when Direct Injection engines were coming on market and GM began the push for Dexos approved oils. I had also been a long time member of BITOG, so I was aware of reports of engine sludge and other problems with DI engines. I asked the GM trainer about this and his response is that that was why the Dexos oil requirements. Based on my rudimentary understanding of how engines work, what do oils have to do with Direct Injection? Oils do not enter the combustion chamber, at least not in sufficient quantity to provide a detergent effect. What am I missing?
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