How can I record multiple channels of audio without the sync slipping after awhile?

Episode 959 (1:21:18)

David from Toronto, Canda
Zoom H4

Leo says that if he can record each mic in a separate channel, he can probably fix it in post. He could just use a stereo microphone and put that in between him and the cohost. Or he could use a standalone device like the Zoom H4, which has a pair of directional mics that can record really well.