Some 18F parts have "power managed modes" that work with EC oscillators, so the data sheet indicates current consumption in EC mode as well as other oscillator options.

In the 18F2420 data sheet, look in the power managed modes section for details.

Note that this does not indicate whatever current your external TTL clock osc is going to eat up. Only what's needed/used by the PIC.

The 819 doesn't have anywhere near the bells & whistles the 18F series does, and all the 819 data sheet can really tell you about power consumption is what the PIC itself requires.

TTL clock type oscillators have their own current specs. You would need to factor that in with what's shown in the 819 data sheet as Melanie indicated.