I would have to side with ihatetochangeoil on this. Over the years, I have used auxiliary oil coolers and filters for transmission, power steering and engine oils. I have commercial plow / landscaping trucks that are used year round and when I talk to fellow contractors they are always talking about how much the new equipment (especially trucks) cost and how the drive-train components are breaking down and how much it costs for repairs, etc. I'm not privy to how their equipment is maintained or how it is used but my trucks with generally smaller displacement engines and lighter duty transmissions outlive their equipment by decades. I keep the fluids cool and as clean as possible. I remember when I opened up the hood of one of my trucks and another contractor, who I was talking with, started laughing because I had a remote filter and a cooler for the power steering fluid, a cooler and a Frantz oil bypass for the engine oil and a cooler and a Frantz bypass setup for the automatic transmission fluid. As years would go by, he was replacing transmissions, replacing power steering pumps, getting engines rebuilt, buying new trucks - all the while I'm still getting service out of my trucks. Sure, I have had automatic transmissions rebuilt. But that was after 150,000 miles of very severe service(daily heavy hauling-plowing)and the only problem with them was worn clutch disks. I have only replaced one (1) power steering pump and have never had to replace an engine (have replaced leaking valve cover or oil pan gaskets). Again, no statistical data go go by just personal experience. The fewer abrasives/contaminants in the oil the better. The better I maintain my equipment, the more money goes into my pocket.