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Triumph TR6 - Dielectric grease (DG)

When removing my dash and all wiring connections I noticed that on some of the connections, especially the amp gauge, there was a nice green colour to the DG that I had applied at time of refit...2 years ago. I have also noticed it on connections in the engine bay. It seems to be only on connections that are covered (like a spade connection). Can some of you rocket scientists out there explain this to me. I thought DG was to prevent corossion.
Rick C
Rick Crawford

Actually DG is to promote conductivity.

At least that's my understanding.

If one were to completely encase the connection in DG (as well as slathering the connection with the stuff) then you would eliminate any contact with air and would eliminate corrosion.

Jim (waiting for the other thoughts)
Jim Deatsch

I only would have added "between the metal to metal contacts" to your first statement.

The grease itself is non-conductive at 12V, and serves to prevent oxidation at the connection points by excluding water. Even better than goose grease!

Brent B

Hi RickC

The green or patinas from the copper. If you take an older wire harness and in some cases remove case 6 inches or more you will still find green. Connection point is the only area of concern. Patina wire still carries same load unless it gets real bad?

Copper with any air contact will patina. If connections still clean your OK. Not sure of why wires with heavy load do it more may be heat or current flow? Know they do it. Think it has to do with current flow?


Bill Brayford

"non-conductive at 12v"?

Can that be possible?

THIS I must investigate, more info, need more info.

Jim (sparky)
Jim Deatsch

It has been ages since I have thought about chemistry, but isn't oxidation the transfer of electrons? So if you have more spare electrons in an area, then oxidation would happen faster?

Ignatius Rigor

"Oxidation" is formally when an atom/molecule loses electrons. "Reduction" is when electrons are gained. The surface of a fresh copper wire will oxidize to a thin layer of copper oxide, very quickly, and is usually no big deal. When you connect a spade or tighten down a screw the thin oxide layer is displaced in sections and current will flow.

Chlorides, sulfur compounds, and carbon dioxide also react with copper to form the "patina" - there are books written on the subject.

Under the hood you find sulfur in exhaust gas, sulfates from the battery, chlorides from hot wire insulation & road dust, CO2 in the atmosphere, heat, and water everywhere, which is what's needed to drive the reactions.

Things are extra bad at connections, especially when the metals are dissimilar. The electrons will help drive corrision at those points, and since those oxidative products don't conduct electrons nearly as well as metal, the resistance of the connection increases over time and will eventually be lost. That's where the grease comes in. It seals the connection from moisture and most all the other oxidizing compounds to prevent corrosion. Sorry for the ramble...

Brent B

Brent et al
Thanks for the replies guys.
no ramble at all...that is what I asked for. I comprehend the oxidation of the metal and the green patina associated with oxidation, what I do not understand is why is the "excess" slathered on/in GREASE turning green?
Does anyone else see this?
Rick C
Rick Crawford


where does it come into play when used in things like spark plug caps in Hi Energy ignition systems and the like?

It's used ON the contacts in that instance.

Is this where we come into the "won't conduct 12 volts" deal but WILL allow (and enhance) ultra high voltage?

Jim Deatsch


I don't know about grease "on the spark plug contacts" - it probably just ends up there. Dielectric grease is used in that application to seal out water so rain or dew won't "short" your ignition, and to lubricate the wire boot so it will come off easily rather than stick to the plug and rip apart . I don't think the grease conducts very well at those voltages, either. The stuff I have looks like a silicone based grease.

Lube greases typically use a metal ion to saponify a lube - lithium grease, for instance. I'm guessing here, but the metal ion may make that grease somewhat less than "dielectric".

Brent B

Dielectric grease does not conduct electricity. The conducting path is still metal to metal. The DG is used to isolate the contact and help prevent surface oxidation. Don't use DG on your plug contacts, you'll end up with no contact. (Unless you may enjoy the sound of you starter motor dying)
Yes it is used to lube the plug boots and isolate the high voltage cables - preventing arcing from the cable to anything grounded in the compartment including other wires. There can be quite a show at the business end of a high output coil. SC
Steve C (member)

Hi All

Rick as I pointed out before the older wires have the green patina all sides of each strand. Back quite aways under the wire cover. I think your green patina is from the grease warming on a high load wire and disolving some patina. Can't think of any harm.

Not to add a twist to this but!
Dialectric compounds are in a sense conductive. Capacitors for one. Now a loose plug wire and lots of grease in the boot under the right circumstances may be an interesting way to hole a piston?? Just speculating guys...:) A wipe on the plug tip and a wipe around inside of boot no problem I have ever found?

I tried to explain in other posts that any circuit not at threshold voltage can also become a ground source and got roasted. Dicourse on Capacativity I won't touch :)

Bill Brayford

This thread was discussed between 06/11/2003 and 09/11/2003

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