How to automate conditional formatting

Alright, I have a work spreadsheet that has two columns; lot number and serial number. Serial numbers are always unique, lot numbers are not. Out if a hundred items in the list there maybe 8 unique lot numbers.

I want to highlight every entry by lot number, and I would like it set up in such a way that everytime I enter a new lot number it gets assigned it’s own color. Initially I was thinking about using conditional formation g (hence the title) but I am not sure that that can be automated.

Is there a way to do this? And I just being dumb?