Thanks. I have a new 550cca battery, and no electrics really (my ra65 has no options). Added alarm, c/locking, driving lights, modest stereo currently running of headunit power (amp going in sometime).
The oil gauge only drops with the successive use of the lights, which is very bizarre. It's a quality unit, I ran fresh thick gauge wiring directly to the sender it and it ain't an earth difference problem.I dunno. I had the same problem with my ambient air temp gauge (measures underbonnet heat) until it carked (another story!)
I'll try running it straight off the battery and seeing what happens.