Gooey stuff on Injectors - how to clean?
 

I purchased some used Bosch fuel injectors for the 300DT. They came well packaged, however they have some kind of white glue or paste both on the threads and the upper part. I need to clean this off before installing; I'm thinking of using either rubbing alcohol or paint thinner. Any ideas?

since the injectors are not supposed to have anything on them, it's unlikely we're going to know what it is, or how to remove it. it could be teflon paste, or hardening thread sealant, or loctite chemical bonding compound... JB weld? no telling what someone put on to stop any leaking from a poor assembly.
I'd send them to Greazzer and have them rebuilt.

Why not ask the seller of the injectors if he knows? If it is gooey I would not be particularily concerned about someone trying to seal up injectors. Unless they did not know what they were doing.

Depending on what the vendor says you might want to spray and pressure test them before using.Used with no known history that is what I would do.

feedback: I just completed cleaning the white gooey paste off the threads (both top and bottom) and some was on the body of the injectors. I used a product called "OOPS! Multi-purpose cleaner" for paint screw ups and the like. I initially began with a product called "Goo Gone" but it didn't seem to work as well. I then wetted a paper towel and rinsed the injectors. They are drying and as soon as they are dry I will install them in the car and give it a go. I am installing new heat shields so this will be a good test. Hopefully everything will go well.