Hi, wondering if the carbon drag washers in my Lews baitcasters should be lightly greased? Thank you.

The only reel I've upgraded the drag washers in, is a Penn 209 which I use for occasional salt water. Shimano actually makes a drag washer grease for these carbon fiber washers. I put a very thin coating on mine when I installed them, mostly to prevent brittleness, and I don't notice any detriment whatsoever. Seems like I read somewhere at one point that it was a good idea but I'm no expert at it.

If using in freshwater there’s no reason to grease or oil then. That’s my understanding at least

I only use enough drag grease on mine to barely see my fingerprint, at least it has worked for me.  I  also back off my drags after each outing.

It won't hurt anything but not necessary either. Grease helps dissipate heat in applications where big fish make long runs DNA to bass.