I’ve been practicing my baitcasting a lot. I’m using Liberty Oil on my Shimano SLX DC. I’d say its definitely the best oil for the best baitcasting reel. I’d suggest comparing some reels first by reviewing articles like these
https://www.tacklescout.com/best-baitcasting-reels/
https://outdoorempire.com/picking-a-best-baitcasting-reel/
https://fishmasters.com/best-baitcasting-reels/
