For decades, especially in the high-end audio world, but also in the automotive world, lots of folks and manufacturers of conductive greases and other products have claimed that these products not only limit water ingress and oxidation, but actually "improve" the flow of electrons through electrical connections. It's a popular concept to market, but difficult to support with scientific data. Conductive greases seem to be most suitable for very high-voltage systems such as those in power generation and transmission/distribution (thousands of volts), where the added resistance is less adverse than the potential for water ingress.

Silicone grease (a.k.a. dielectric grease, disc brake caliper grease, personal lubricant, etc.) is an insulator, so it is great for applying to the outside of the battery post/terminal assembly, as long as it isn't applied to the contact surfaces. I agree that this is a better product for sealing the battery terminals than conductive grease. The spray-on paraffin-based battery terminal protector products are generally pretty good too, and less likely to creep down between the battery posts and cable terminals in a hot engine compartment. CRC makes a good long-lasting one.

 

In all seriousness, there's a good reason.
Firstly, this is done for fresh install. Thus, there's a parallel spec for degrees of torque post crush washer contact. I have noticed two things and tested them. The change in both is minimal with the supposed "lubrication".
Next, I only do this for certain cars which happen to have very crummy sealing of the wells. On my Hondas both with short term and long term plugs, there has never been an issue at removal. My friend has the same XK8. We installed new plugs in clean wells, proper NGK, proper torque with a known good torque wrench. One could feel and it worked out that the degrees of torque for complete torque and washer crush were spot on with the torque setting. 70K miles later a few were welded in place, and I had to remove both heads to get them out safely, yuck. There was no evidence of water infiltration into the wells, perhaps light moisture over long time is enough. There's definitely some sweat on the foam gaskets whenever I remove the well covers and water never touches my engine, his and we live in the desert now. Go figure.

No car design is perfect. BTW, you want to really ruin an AL head. Have a plug too loose. After install, go back and check the torque after a few minutes. Often needs a little more. This is a spec for many things as fasteners yield and is required by procedure and temperature in many situations.

 

Be very careful cleaning the terminal connectors with anything as their coating can be removed which will enhance corrosion. A light scotch cloth is often enough with some solvent to make them shine.

 

Thanks, that is good to know.
I hate taking apart something which is currently fine, however when I am ten years older and parts that much scarcer do not wish a nice surprise. Plus, replacing a subframe or having to sleeve it will not be fun or easy or the latter advisable.

 

Yes, that stuff has lower viscosity and seems to travel places. Funny how things which should be rather clean jobs turn into...
My personal favorite is how the rear universals throw grease everywhere making clean jobs a lovely mess. And, the muck causes just enough adhesion to trap dirt and grit just above one's eyes.

 

Sorry, I meant the abrasive sponge or scouring pad, like the kind used to clean machine tool tables (it's very mildly abrasive, less so than a wire brush). It looks like a kitchen scouring pad, but it isn't; it doesn't scratch. I'll send you a picture of what I use. If it's sandpaper, it should be fine (400 grit). I completely agree about grease on electrical contacts; it's best not to use it (you have to clean them when disassembling). In any case, for the battery, use battery contact protector spray, which dries after application. For other electrical contacts, no grease; for cleaning, use contact cleaner spray or isopropyl alcohol.

 

Yes, that's what I had in mind.
FYI, never use even those to clean areas where anything can get into the engine or other mechanicals such as when cleaning a gasketing surface. They have particles in them which are some of the hardest things on earth only varying the abrasiveness by particle size and quantity. They shed in use. Nasty stuff in the wrong places.

 

this is my opinion as well.

Perfect metal to metal connections are the holy grail. Sadly, the holy grail is elusive.

Just my experiences, and perhaps no one else’s; microscopic air gaps have a way of getting in the way of perfection. And corrosion follows. In those cases, a conductive grease is better than using nothing, in which case some type of unwanted corrosion always seems to eventually intrude, especially where humidity fluctuates.

I haven’t been able to measure any resistance in the connections where conductive grease was used. Perhaps using a more sophisticated meter might have a different result. But with my consumer grade equipment I seem to be getting acceptable results when using the grease.

Z

 

Ditto!

 

Agree with the response regarding good shim and washer clearances being important as burrs tend to be the biggest factor inhibiting withdrawal. grease/copper slip etc is secondary.

 

Yesterday I was able to remove both side's fulcrum bolts and struts.
Was going to report this anyway.
Driver side was beginning to bind, had some oxidation on the bolt in the open section of the subframe and the shims were binding on the rearward side.
A little grease in the subframe opening fixed one problem, however I discovered something which worked amazingly well for the stuck shims on a lark.
Two drops of motor oil on the shims, rotated the bolt a few times and was able to tap it out no problem.
Sometimes the simplest things work.