Following up on my earlier post about needing to connect No. 6 aluminum
in the wall to (amazingly thin) No. 16 copper for the new oven ...

I haven't found any connector made for No. 6 aluminum and No. 16
copper. A split bolt I've seen is for 6 through 10, and a Polaris
connector I've seen is for 4 through 14. Two appliance installers have
told me they'd just use a wire nut (one guy specifies a gray or maybe
blue one). An inspector and some electric supply guys think a wire nut
is a bad idea. I don't much like the idea of using a split bolt rated
for a larger wire. One installer says they're kind of a mess and
require two kinds of tape.

The Frigidaire oven manual says the insulation on the wire is rated for
higher temperatures than ordinary household wire insulation. The
manual, for more than one model, says the oven draws "up to" 4000
watts, but a plate on the oven says 3.4 kilowatts at 240 volts. So
that's either a max of 16.7 amps or 14.2 amps. The old double oven had
gray wire nuts.

What would you do?