I use this all the time . It works very well just make sure you cut off as much as you can 1st .

Does it work on really old sealant?

thanks op

Does what it says good stuff

thanks op

Used it in past works ok as previously mentioned you need to get most of the sealant off first to get maximum benefit. Word of caution, doesn't remove the sealant off brickwork very well if it's around a PVCU window but around baths e.c.t. works good. Heat

I've tried this and other types - never had any effect.

Much prefer a stanley blade and solvent cleaner.

I've used this before ,can require multiple applications... but does work