I was in at the shop yesterday having a coolant flush and oil change done on my car. While waiting for my car, I was looking around the shop, and I saw on an ornamental shelf two very old cans of motor oil. According to the guy behind the counter, a regular customer had found them in his garage, and thought the garage would like them as an interesting display item. They were cans of Castrol 20W-50, with service ML-MM-MS, so they were probably at least 40 years old, but still full. The thing that caught by eye was the inscription on the can was "high-performance motor oil formulated with liquid tungsten for maximum protection". I've never heard of tungsten being used in oil before, must be a very old thing. I guess it was used to increase the high-temp. properties of the oil, because in looking it up, I found this out about Tungsten: "Tungsten chemical compounds are used in catalysts, inorganic pigments, and tungsten disulfide high-temperature lubricants which is stable to 500 °C (930 °F)". Any one else heard of this or ever used oil with this in it? Is it still ever used?