The debate over conventional vs. synthetic oil is heated in almost all aspects of the automotive universe, but is fairly settled where turbocharged engines are concerned.
Synthetic oil is made by singling out the individual molecules that make oil slippery, and reassembling the lubricant without any of the conventional oil's contaminants.
Conventional oil contains a number of paraffin waxes, carbon molecules and additives that break down at high temperature and turn into sludge.
The oil in turbochargers come in very close contact with red-hot exhaust components, and cooks a little more each time it goes through the turbo, getting thicker as the miles go by.
Oil sludge collects in the turbo's drain line, preventing elimination of hot oil and causing turbo overheating.
Synthetic oil maintains its lubricity (slipperiness) longer than conventional oils under high-temperature conditions. This is especially important to turbochargers with their tight bearing clearances, high component speeds and heat-induced metal expansion.
Synthetic oils are almost always required by modern turbo-car manufacturers. Failure to use it will void the warranty.
