Originally Posted by
Bianchigirll
Personally I’d use that liquid wrench to get it loosy goosy then blow it really good and use some tri flow or other high nylon content lubricant. Liquid wrench might not play well with the plastic internals. But this is just my opinion.
"Liquid Wrench" as it applies here is actually a
brand, not a particular product. They offer many different aerosol sprays, I chose their "Lubricating Oil" product, it's just that.
Oil, to the extent that it (perhaps slowly) frees up stiff grease, is much longer-lasting than the more heavily-diluted (with kerosene or it's equivalent) WD-40.
Not unheard of though for old grease to thicken again after just one season, so flooding out a lever with WD-40 or a degreaser is a preferred first step for many.
Note that one can work the pawls through their full range of motion without swinging the levers through their full travel, and without even making the shifter click. Just pushing the lever (either one, actually) enough to first engage the pawl effects the needed pawl movement during a flush-out, sparing the lever return springs from a vigorous assault on their fatigue life!
Getting lubes between the lever and rubber hood is to be avoided at all costs, so I always position the bike tipped forward at least 30 degrees before spraying lubes into them.
Shimano STI levers do indeed seem to be the ones most afflicted, due to their pawl-and-hair-spring internals, with relatively long pawl-pivot bores that trap a broad area layer of grease that is sheared by pawl movement and (relatively weak) spring force.
But
all integrated levers rely on lubricants to give smooth shifting action.
Newer Shimano STI levers (having hidden shift cables) offer visible access to the pawls, allowing pin-point pawl pivot lubrication in lieu of messy flushing.
And SRAM's levers expose their release latch (that needs occasional lubrication to minimize the needed force at the lever when releasing cable).
I use a tiny spritz of heavy-duty PJ1 motorcycle chain lube there because it's designed to lubricate steel parts in a dirty environment.
Campagnolo's most-common Ultrashift mechanism (having replaceable indexing springs) needs to come apart to re-lubricate the indexing guts (with grease), and typically get new, inexpensive indexing springs installed at every infrequent overhaul.
Kind of unrelated to this discussion, but I do have the cringe-worthy habit of merely spraying lube into the greased indexing cavity of Campagnolo downtube Synchro levers in order to put an older bike back on the road, and which mostly restores their smooth, crisp "snap".