sorry, but diesel engines using dino juice for decades with their turbos had zero instances,using conventional oil, yes synthetic is better but conventional oil works on any engine if changed regularly.the only reason sludge is created is from lower oil temperatures.....not higher temps.
Absolutely correct for diesel. mldavis Comments didn't call it out, but they apply to gasoline engines. Diesels are completely different, diesel exhaust temps are MASSIVELY lower than gasoline, so as much as the mechanical design of the turbos are similar, they are not subject to the problems of "cooking" oil when shut down.
Not that it also takes some effort to produce a useful catalytic converter system for diesel, because the exhaust is so much cooler (and cats use exhaust temp to light off the chemical process that reduces the noxious stuff in the fumes)
Edit - had to add - this is why turbo has been so prevalent in diesel engines for so long. It's a VERY efficient and reliable way to increase combustion volume, but it doesn't translate to gasoline easily. Go look for super/hyper-cars that have turbos. There aren't, and never have been, many.
Edit #2 - sorry! So Synthetics can be engineered to be less prone to damage from high heat, but there's currently no materials technology able prevent it completely at the temperatures seen in an exhaust system of a gasoline-fueled engine. If you run 12.6 at the strip, then park and shut down the engine, you will cook the oil, period, no matter what kind it is. It may only be a little, but there will be deposits than can cause wear, or limit flow, and over time, the engine will be ruined.
Edit #3 - SORRRY!!!! But thinking about it, most people don't realize just how much of a difference a seemingly small difference in some process can make. In this case - exhaust temps, and the effect on oil. Anyone who cooks, however, knows that there is a fine line between perfection, or absolute ruin, of ingredients over a stove - sugar (candy), chocolate, eggs, even - to some degree - more forgiving items like steak or fish. You can totally destroy them if you don't heat (cook) within a certain set of parameters.
Oil is the same. Even synthetic is an engineered organic molecule. You may think the seemingly insignificant difference should not matter, but it does. As you approach a limit, chemical composition breaks down quicker than most people realize, and if you cross a line, you can't just back off and expect it to return to status quo. These processes - cooking, or lubricating - have one-way doors to total failure. They can happen in the blink of an eye, and in your engine, all may seem well, but there could be terminal damage being done as a result of a simple, short overheat condition. It will just take time to show up - like selling spoiled candy in a store for a few weeks. Only after you get enough complaints will you realize a mistake was made....
