The oil inside a commercial jet engine must withstand temperatures exceeding 200°C while circulating through bearings spinning at over 10,000 RPM, all while the outside air is -56°C at cruising altitude. These synthetic oils work in a closed-loop system that constantly filters and recirculates the same oil throughout multi-hour flights, unlike car engines that simply store oil in a pan. A typical jet engine holds only about 5-8 gallons of oil despite being far more powerful than any car engine, because the oil is so carefully managed and cooled through heat exchangers. If the oil system fails during flight, the engine must be shut down immediately, as bearings would seize within seconds from the extreme friction and heat.