Scion tC

I changed my brakes a year ago, used some, come to think of it, quite thick silicon based grease (Valvoline "synthetic" stuff you can buy at Advanced Auto Parts) for the calipers. Lubed them up quite good. Silicon grease not Lithium because the Lithium grease will eat away the rubber caliper cover/sock.

The symptom I'm trying to remedy is a bit of "lag" in braking response. I press hard, response takes a bit for the brakes to engage as stiffly as I pressed. I don't have air in my lines, I am certain of that due to how much fluid I put through them when flushing, got all the air bubbles out. I may have air in the master cylinder, haven't gotten around to bleeding it, going to do that here next.

Can anyone recommend a special grease that would be good for brake calipers? Lithium grease is nice and fluid and is what I would *LIKE* to put in there.