1990 LS400, 64K miles, oil changed every 3k since new.
I had the same problem two weeks ago on my way to San Fran. I was out in the desert in 100+ heat and the oil light would come on for 10-15 secs @ 85mph. No gas for 20 miles. Sweating it out, I finally made it to a Mobil station and checked the oil. It looked like it need less than a 1/2 qt. So I carefully topped up (about 1/3 qt., 5w/30) Problem solved!! It needed just a little oil for some reason. The oil sensor is very sensitive. The dip stick is also very hard to read compared to other cars I've owned. Try putting in a small amount of oil and keep the rest in the trunk. I'm bet you're not leaking oil. You just need to add oil periodically.
