Can someone tell me what the oil readout (%) means on my Civic Hybrid? A service rep told me that it indicated the remaining viscosity of the oil, and that when it reached 10% it was time for an oil change. I have put over 5000 miles on the car since my last change, and it's showing 40%. If it's actually measuring viscosity, I assume use of a full synthetic would be better in terms of the frequency of changes.