What's the rate of evaporation/loss of a full synthetic engine oil?

All engines pass at least a wee bit of oil to the combustion chamber. How much depends on the individual car, how many miles it has on it, as well as its driving environment. On a 2003 it’s impossible to guess.

Assuming you just got the vehicle, you need to check your oil every few days until you get a “handle” on what your normal usage is. Anything from a quart every 1,000 miles to no significant usage would be normal. City driving tends to be more becaues it spends

By the way, it does not evaporate. It gets burned. There’s always a miniscule amount that remains on the cylinder walls after the oil rings pass by and provides some lubrication for the compression rings, and that gets burned in the cylinder along with the fuel.