KCT1986

For the 65xx series of shifter, they are all double/triple capable. Models are 6500 pre-Flightdeck, 6501 w/Flightdeck, 6510 updated model w/Flightdeck.

The 6503 marking was used on cranks and front derailleur but not on the brifter since all worked with triples.

The left shifter should have multiple clicks for FD trimming. Clicks are as followed:
. From smallest chainring to large; 2 small clicks for trimming on smallest ring and third click for middle ring (full stroke of large lever). Another click for large ring (another full stroke).
From large chainring to small; 1st stroke and release of small lever shifts to middle ring. Light (click) release of small lever to get trim position on middle ring, Full stroke of small lever to get to the smallest ring.

For a double chainring set-up, use the position for the smallest and middle position so trim positions are available. Connect cable to FD while in the lowest position on the shifter. This will give you 2 trims while on the small ring. While on the big ring, you'll have 1 trim position towards the small ring (light release of small lever).

Not sure about what lube to use. Maybe not something that would create a waxy build-up that would be hard to clean by flushing in the future.