To determine the condition of the piston ring seal--do a compression check--first 'dry' and then with a tablespoon of oil added to each cylinder and cranked a few seconds before checking. If the two measured pressures are reasonable close (10-20# different) ring seal is good. a large difference indicates leaky ring seal.

With 5W30 oils, you can (and in So Ca-will) lose up to 20% of the oil from EVAPORATION, especially with 'conventional' lube oils. 5W30 is too light for that climate. 20W40 or 20W50 is much more appropriate.