I was looking for some sort of formula for calculating their values specifically for the crystal to be used. Infineon app note AP242005 provides a nice discussion of oscillator requirements and operation for their C500 and C166 processors, I was looking for something similar for the 8051 family. I suppose calculating cap values is not necessary due to design of the controller.

I am looking at the Philips 80C51 data handbook and see the capacitor values in the On-Chip Oscillators section. I can only assume that the values of 30 pf for quartz and 47 pf for ceramic at f<25 MHz must provide for the desired fo as set by the crystal, whether 11.0592, 12, or 4 MHz. Experimentation will prove operation.

Not designing oscillators for 20 years doesn't help me remember rules of thumb and what's important.