Trying to build a metal detector.

[Refrigerator]

Hey.
the title says most of it. I'm trying to build a metal detector that would be stable and sensitive. I've built one already, it's "the metal detector MK II" circuit but it's unstable and hard to set up, the sensitivity tends to start drifting up or down and I can't get to that sweet spot where it's the most sensitive.
I want to do something similar to that one, but i'm thinking of using a Colpitts oscillator instead of the one in the circuit of the MK II and i also have plenty op-amps laying around to use, so yeah why not use those.
I want to make the colpitts oscillator resonate and the inductor would be my Tx coil, while i could do the sensing part with op-amps, i have many quad op-amps from a vintage audio receiver ( too many actually ) one of them i think could be just a buffer, maybe with a gain setting, while the other one would be for the sensitivity setting, yet i'm not sure about how should i go about doing the receive coil.
What i'm asking is would it be possible for the colpitts oscillator to effectively drive the Tx coil and if it would be powerful enough to do it without getting stopped, and also where could i find a simple formula to set the colpitts oscillator to work.
Thanks for help.
Ps: my selected frequency is about 33kHz.