I have used "Collins Sewers Aid" for the last 4 or 5 years and it is fantastic.
I lube up all my traction kite lines as well. It not only makes them friction free without gathering dust, it also restores the dye/colour of the power line itself.
It also helps laydown the fluffy fibres on the wear areas where the lines are constantly in contact with each other.
2 more bottles arrived here a few days ago in the post from the USA, as it's a bit hard to get in Australia.
The post cost as much as the product.
But it is well worth it.
Just be very careful not to lay or pack the freshly lubed lines on a kite, as sometimes (some heavy dyneema with lots of colour, usually red) the line colour will bleed and stain your kite.