American Standard "Williamsburg" tub & shower faucet.
They sent replacement cartridges for the water control & "pressure balancing cartridge" - (maintains hot & cold balance).

Should I grease the o-rings & seals before installing new cartridges?

Per A.S. support, the only instructions on installing them are from the original "rough in & installation guide."
Install: [www.americanstandard-us.com]

Parts: [www.americanstandard-us.com]

For * this * faucet, nothing mentioned about greasing (e.g., silicone) the seals / surfaces, before inserting new cartridges (many gaskets, seals).

For an A.S. , single handle kit faucet, they sent instructions w/ replacement cartridge & INCLUDED silicone grease. Mentioned places to apply the grease.

Thanks.

use silicone grease on any and all rubber rings.

I went one better than that.
Even though the faucet is only 10 yrs, the tub gets light use, the seals / o-rings of pressure balancing cartridge inside the brass body leaked. And Am. Std's support / CS was not stellar, by any stretch.
Limed up the plastic cartridge, so it was hell to get out. Front part snapped off (cheap plastic crap, on expensive faucets).

When I finally got the broken cartridge out (MUCH later - after soaking w/ vinegar), had to use vinegar / CLR acid to clean the minerals off inside brass body. Esp. where seals / o-rings would seat. That took * a while.* Longer than I ever want to spend again. I'm not a newbie at this crap.

Finally got all sealing surfaces of brass body clean & the bulk of other lime that would interfere installing new cartridges. Coated * ALL * surfaces w/ silicone. Entire inside of brass body; entire outside of plastic cartridge fitting in brass body. Yes, lime was stuck to the old plastic cartridge. And coated all o-rings / seals.

Also coated all screw threads w/ silicone, so they'll come out - if needed. Yeah, took a while longer.
But next time this faucet needs repair, I'll be so old / frail, I wouldn't be able to deal w/ this same crap - or afford to pay a plumber.

someone (be it you or a plumber) will be happy that you greased things the way you did.
don't forget the end of the stem so the handle comes off easier.

I put a little silicone grease, only as much as would make parts shine when rubbed with finger, on replacement cartridge for two-handle Price-Pfister kitchen faucet. Afterward, water flow was dramatically slower and we blamed the grease and I went through headache of taking it all apart again and washing/wiping the parts! I still don't know if that's what it was.

You have to remember.Rubber washers harden over time, especially if you have hard water.Grease them up once a year.

Sounds like you may have an unknown object caught some where in the valve.take it apart and make sure
nothing`s in it.Some time you may have calcium build up blocking the opening`s for the water to pass through.