I took my Tr7 to work last night, the weather is finally nice enough here on Vancouver Island to drive with the top down. Drive to work was great, warm and sunny. However in the morning when I started it, the oil light was on, it was dark at the time so I couldn't see very well; however, I had oil in the trunk and added about a litre and the light went out. Drove it home 25km, went to bed, got up and went to check for the reason for the warning light. What I found was amazing, I had left a trail of oil for at least 2km from my garage back to where I turned off the freeway. Talk about marking your spot. The leak was caused by the oil pressure switch which had failed.
Moral of the story, oil pressure light could be trying to tell you something.