Wouldn't Didi-7 have a bleaching effect? Nasty... On the rare occasion I wear a tie, and the even rarer occasion I get a greasy mark on it, I usually give the stain a gentle rub with a damp cloth, either by itself, or with a tiny bit of regular soap, or with a tiny bit of eucalyptus oil. (I maintain eucalyptus oil will get anything
out - you just have to air out the garment in question for a few days to get rid of that, um, bracing
As for watermarks, I usually blot with a tissue, then blow-dry. I've never had a problem with this method, but apparently it's fraught with peril, and you risk setting the stain. Wait for a second opinion... You can also buy little sachets of silk-cleaner at a lot of department stores, usually chock-full of 'aliphatic hydrocarbons', which is kinda like a fancy way of saying 'fat-dissolving compounds'. I have an instinctive distrust of these, don't know why, so I'm yet to use them. (I will, though. I'll grease-stain a couple of old ties, try it, and get back to everyone.) Option three, Tiecrafters
is generally well-regarded as far as tie-rejuvenation goes, but I haven't used them myself. There's a shipping address on their website, you just mail them your ties - there's a four-tie minimum - with instructions, and they do the rest.