Diafine is used at stock strength, then returned to the storage bottle for subsequent use.
Replenishment amounts to simply replacing the lost volume of Part A, and adding the same amount of fresh Part B to its bottle.
It's highly insensitive to temperature and time,
but it IS sensitive to agitation, which should be minimal and gentle.
The OP's description of his agitation procedure sounds reasonable as long as the rotation was not rapid.