Yes. Conductive paste is great.
I used lgb, and then, auto graphite grease. They were equally good.
Heres a tip. The mechanical fit must be clean and tight, like new track.
I suggest that the inside of plates be very clean, using liquid flux and a cotton swab and thorough rinse if old and oxidized. Metal polish will do too, but is more work.
Then a very snug fit too. Gently crimp those fishplates provided theyre not too brittle. I find the aristo plates to be......flimsy, after a year or two.p
The grease, in my years pre track clamps, kept all the micro crud out of the joiners. This is the super fine silt like stuff from wind, water, that finds its way into the fish plates. The grease traps it, and block damp and water too.
You didnt ask, but i will offer this. I used conventional plates for fifteen years, in dry colorado. Rarely had electrical gaps but for snow and rain.
I bit the bullet and got track clamps, and, it is better. I have no electrical issues, other than needing to clean the rail tops as needed. I was resistant due to cost, but the reliabilty is lovely. Makes running headache free. Just a thought.
Best.