Otter Butter is a line grease (floatant) that contains no silicone making it a favorite of people who use real silk lines on varnished bamboo rods. Residual silicone can be difficult to remove completely and may cause issues if you ever need to have a varnished bamboo rod refinished, hence its popularity with the varnished rod crowd.
I use it exclusively on my silk lines on my bamboo rods because for me it lasts WAY longer than the old standby, Mucilin.
That being said, both Otter Butter and Mucilin will melt if exposed to temperatures you experience on a summer's day and leak all over the place. I carry a bit of my Otter Butter in a screw top aluminum pill storage "capsule" with an O-ring to minimize that issue, however...
If I feel the need to apply a floatant to my plastic lines or furled leaders and I am not using bamboo, I use
Loon Payette Paste that does have silicone, but works great and DOESN'T melt (I tested it in an oven at over 150 degrees).
Spray-on floatants are out there, but they are most costly for less product and the container is larger.
Bottom line, cleaning your line with regularity as recommended by that line's manufacturer is all you really should ever have to do and is better than not cleaning your line and using a floatant.