With all the time I spend reading on here, I got to thinking about all the oils discussed, which sparked a question I have always wondered. My back ground consists of working on heavy equipment and oilfield engines, these engines all used decent quality dino oil out of drums or tanks...depending how big the engine was, and generally speaking unless there was a mechanical failure, I have yet to see any problems related directly to the oil being used. So my question is, has anyone ever legitimately fixed a known problem by changing to a specific oil? I can understand going to a thicker oil due to a knocking rod, or maybe a thinner oil due to hard cold starting...but what I'm asking about is switching to brand B cause brand A was creating whatever problem. I get tangled up as much as the next guy into all the different oils, but is there certain oils out there that actually have proven to be obviously better than other similar oils? Not looking for a brand war or another dino vs synthetic debate...just looking to expand my knowledge incase I have been overlooking something.