Silicone grease is the same thing as dielectric grease.  It boils at 200°C  and will become a sticky mess.  You could argue that the sticky mess is better than leaving it with nothing, as the boot might stick even more to the ceramic without it.  But I'm not going to test the theory.  

Edited 19 January, 20206 yr by A01

Never experienced a 'Stick mess'  while working with spark plugs.......

Why bother with grease as coils can be pulled out without it. I've done it. 

I'm unlikely to change my plugs any time soon, having done only 1500 miles so far, but when I do, I doubt I'll use anything on the plugs or rubber covers.

 

I would however make sure the ceramic shafts of the plugs and the insides of the rubbers are very clean, using isopropyl. Just like you would do on a headlamp bulb that had been touched. Even the grease from fingers will break down at temperature and help glue the rubber to the plug shaft over time.

 

Also, all sorts of chemicals leach out of the rubbers anyway (it's not rubber as such), so it's worth an occasional removal and clean if you are worried - but on the other hand, you won't buy many plugs during the car's life, so why not change plugs and rubbers at the same time, even if you have to buy new coil assemblies?

Edited 20 January, 20206 yr by freemansteve

I did mine two years ago. I studied the comments available at the time and it was obvious that you needed to be careful removing the rubber boots. I decided not to use any kind of tools to get them off. I ran the car for a short while and then let it cool down enough to be able to work on it. After unbolting the coils I simply started pulling and twisting but without appyling too much force. I had to continue this for a good 30 seconds or so with each boot but they eventually let go and came off in one piece.

 

I didn't bother putting anything on the plugs or boots, just reassembled everything. I figure I probably won't own the car when the plugs need changing again...

Roottootem, I notice your list of vehicles does not mention the citigo.  

 

For anyone who has not done this on a citigo or another vehicle with the similar (not ribbed, not tapered) sparkplugs and interference fit rubber boots  you have probably never experienced anything like this.  In these threads the guy who took it to a garage, the mechanic said he has never experienced such problems with plug removal.  The OP on the Up thread said "that it was an understatement".  I have been changing plugs for 30 years and never had anything like this.  If you stick anything round cylindrical which is bigger into a tight round rubber tube you will always get this "locked in" effect like those chinese finger traps.

https://www.quora.com/Why-are-Chinese-finger-traps-called-Chinese-As-a-Chinese-I-havent-seen-this-before

 

hot plugs are essential to help removal.  If these snap inside the well you then have to dig them out, it's not going to be fun.

 

I will remove my boots again in the summer because I just realised,  "doh!" "facepalm",  I only have to remove the boots. I can leave the plugs alone. I'll  find out if my talcum powder is the best solution.  

 

In the mean time, if you are reading this and are needing to change your citigo plugs and I have not updated.. and you want to know if you should use talc for refitting, then put a reply here asking me to update and if I see the email notification I will do my best to accommodate you.

I would hate to bore you with the cars I owned or worked on or drive over the past 4 decades working in the motor trade and dealing in cars. But spark plugs a plenty I have changed on all skoda models and older and newer, it is just something that one does. 

Edited 22 January, 20206 yr by Roottootemblowinootsoot