* I ditto Jfawcett's experience. I've used SST Cryo-Seal for years. Works as advertised. Small to medium leaks. If you use it and the seal doesn't hold, then you have too big a leak (that seems reasonable!). As a last ditch effort before spending a lot of money on replacement parts, like an evaporator, it's well worth the money. If you had a W140 with a very expensive leaking evaporator, and the sealant bought you several more years of service, you'd be dancing in the street.
* Another important feature of the SST sealant is that it separates out with the oil when the system is discharged, leaving any recycling machine unaffected (unlike other sealants, and another reason why I use it). However, if the freon charge which includes the sealant is lost or recovered during service work, you'll also lose the sealant and will need to add more sealant with the new freon charge.

__________________
ASE Master Tech
Quality Enterprises
Mercedes Svc. & Restoration
Sheridan, IN
317.769.3536