What Benefit Does Dielectric Grease Provide !.....

Idrinkmotoroil · Jun 3, 2004

Just wondering if someone can educate me on Dielectric grease, the stuff some people recommend for spark plugs and plug wires.

I've seen that some wire manufacturers recommend dielectric grease on their boots , and many even give you a small tube when you buy their wires. I've also read packages of Dielectric grease which claim to increase spark energy and protect electrical problems.

Now does Dielectric grease just keep spark plug wires from sticking to spark plugs ?, or does it enhance spark energy between the wire and the top of the plug ?, or does it do both ?. Most instructions I've seen say to put the dielectric grease in the spark wire boot and then put the boot over the spark plug. This would coat the top electrode of the spark plug as well as the inside boot ot the wire. So does Dielectric grease promote spark energy through it as it comes between the wire connector and the top of the plug. Or would it reduce spark energy transmission ?.

Whenever I removed wires from plugs that had dielectric grease on them the plugs apppeared dirty, the grease had blackened up likely wher the spark energy passed through. It cleans up easy enough though.

I have seen problems where plug wires that did not use dielectric grease would arc over to the plug and cause carbon tracking on the plug. This always causes problems in the long run with mis-firing. So does dielectric grease prevent arcing and carbon tracking ?

Lots of questions, just wondering how this little grease works. thanks for any info.

Joey

sbc350gearhead · Jun 3, 2004

Dielectric grease does not conduct electricity, and seals the boot from moisture, as well as preventing corrosion.

Idrinkmotoroil · Jun 3, 2004

quote:

Originally posted by sbc350gearhead:
Dielectric grease does not conduct electricity, and seals the boot from moisture, as well as preventing corrosion.

thanks for the quick reply. So really it just needs to be applied to the inside layer of the wire boot.

Instructions of the stuff often say to coat the top end of the plug and coil terminals. In my thinking this would hinder metal to metal contact and reduce spark energy unless dielectric grease conduted energy. But you said it doesnt which answers my question very well. I just wonder why manufacturers of dielectric grease tell you to coat the contact surfaces, one maker of Sylglyde goes so far as saying it will increase spark energy by a certain percentage. You can see why it gets confusing.

thanks again. Any other info feel free to jump in.

Joey

T-Keith · Jun 3, 2004

It should be applied to the boot and the ceramic portion of the plug. It keeps moisture from reaching the electrode and the spark from arcing through the insulation and cracking it.

-T

Idrinkmotoroil · Jun 3, 2004

Thanks very much fellas. That helps alot. I've had arcing problems on my stock wires and plugs so I've gone with aftermarket wires and needed to know how to use dielectric grease. I will now be careful with it's use on the plug. There is so much mis-information on this stuff when you purchase it. They guys who sell the stuff tell you to bathe the plug in the grease and pump the wire boot full of it. I just could not see how that would help anything if you coated the electrical contact surfaces. Thanks again , much appreciated !

Joey

porterdog · Jun 3, 2004

quote:

Originally posted by Idrinkmotoroil:
They guys who sell the stuff tell you to bathe the plug in the grease and pump the wire boot full of it. I just could not see how that would help anything if you coated the electrical contact surfaces.

Seems weird, doesn't it? Using an insulating/non-conductive product on the contacts? IME though, it's not that good of an insulator so there's no danger in getting it on the actual contacts. The strength of the product is that if thoroughly applied it will keep air from the contacts and thereby prevent them from oxidizing. Oxide IS a good insulator, generally.

I just used this last weekend while repairing the headlight switch on my old Audi 4000q; the dash lights had gone intermittant. Took the switch apart, cleaned the contacts, bent them a bit for better contact pressure, lubed the whole thing up with sylglide plug boot grease, and reassembled. Works good now!

$0.02,
Robert

Kestas · Jun 3, 2004

You really just need to butter the inside of the boot where it contacts the ceramic. This "increasing spark energy" claim is a real stretch. It's true only insofar as it prevents potential problems.

It can also be used on underhood electrical connectors. Whenever I disturb connections, I first make sure they're clean, then pack silicone grease in there before reconnecting. The silicone excludes the corrosive environment resulting in fewer problems as your car ages.

cryptokid · Jun 3, 2004

somthing interestning i found out is that just about any oil (even motor oil) or grease or vaseline is dielectric.

Idrinkmotoroil · Jun 4, 2004

hmmm, I see, that's starting to make sense now. You use the grease to exclude negative impacts on the plug and wire, yet the grease is not affecting the spark energy as it isnt that good of an insulator. Thanks again for all the great info, this stuff can be confusing when you think about it too much. he, he.

Joey

rg144 · Jun 4, 2004

Also the old reliable Vasoline Petroleum Jelly. Cheaper than the stuff at the auto store to slather on the battery terminals to prevent corrosion.

brianl703 · Jun 4, 2004

quote:

Originally posted by cryptokid:
somthing interestning i found out is that just about any oil (even motor oil) or grease or vaseline is dielectric.

Dirty grease/oil isn't! The carbon conducts electricity.

My spark plug socket was full of dirty, nasty grease and oil. The spark plugs installed with that socket had carbon tracking marks on them (and the car had developed a misfire).

From now on, I make sure that spark plug socket is clean.

widman · Jun 6, 2004

Yes, oils have dielectric capabilities, but they are normally low. A normal hydraulic oil will be around 20 KVA, while you should have 35 or so for the bucket trucks. Transformer oils are around 35 to 40. They are good at transferring heat but not moisture.

DavoNF · Jun 15, 2004

IDMO,

I am confused as well. This bit of infor is from the whatis website, and needs explaining.

quote:

If the voltage across a dielectric material becomes too great -- that is, if the electrostatic field becomes too intense -- the material will suddenly begin to conduct current. This phenomenon is called dielectric breakdown. In components that use gases or liquids as the dielectric medium, this condition reverses itself if the voltage decreases below the critical point.

So the question is, does the silicon di-electric grease on the spark plugs or other electrical connections suffer "dielectric breakdown" when necessary to conduct a nearby current, but remain an insulator at other times.

Anybody know?

cheers
Dave

labman · Jun 15, 2004

Apply a high enough voltage, and almost anything will conduct a little. What is called a dielectric grease is a grease that has a higher than average dielectric, resistance to conduction. I have seen the dielectric greases as preventing the spark plug boots from bonding to the spark plug insulators. That was a big problem in my Grand Am Quad 4. You would pull the coil housing off the plugs, and half the boot might stay. A little applied to the insulator kept the boot from bonding, and may have helped with dirt and moisture. I doesn't seem to me like that used to be as much of a problem as it is now. Maybe when you pitched plugs that had done 10,000 miles, the boots didn't have a chance to bond.

When I worked for a wire and cable company, the wire all had an insulation resistance rating. Nothing could pass the test if it was too humid, the damp air would short it out. Perhaps the test was to done under controlled conditions. the interesting thing was the high voltage cable. The bare conductor was first coated with a semi conductive polyethylene. Then a heavy layer of pure polyethylene which could resist the lower voltage on the outside of the semi conductive. Partly this was about charges accumulating on the least little nick or scratch, then burning through the insulation.

[ June 15, 2004, 10:33 PM: Message edited by: labman ]

brianl703 · Jun 15, 2004

quote:

Originally posted by DavoNF:
So the question is, does the silicon di-electric grease on the spark plugs or other electrical connections suffer "dielectric breakdown" when necessary to conduct a nearby current, but remain an insulator at other times.

Under normal circumstances, silicone dielectric grease won't have a dielectric breakdown. You don't want it to have a dielectric breakdown, ever--if it does, that means the electricity is not going where it's supposed to be, resulting in a misfire.

I suspect that it's dielectric breakdown voltage is higher than that of air, and that is one major reason for using it--as well as the fact that it keeps moisture out of the connection (and keeps spark plug boots from getting stuck).

DavoNF · Jun 15, 2004

Thanks fellas.

I smear it on my fuse blades with no ill effect. I live about 100yds from the sea, and you can watch things rusting here.

Not the same, but have you seen this Canadian stuff, a contact enhancer with a difference.

http://www.stabilant.com.au/stabilant_22_-_technical_notes.html

Intesesting.

Dave

[ June 16, 2004, 01:32 PM: Message edited by: DavoNF ]

brianl703 · Jun 16, 2004

I've used Deoxit D5 before, which is similar to the Stabilant 22 product.

Deoxit is quite good for fixing bad volume controls.

kevint · Jun 20, 2004

I use dielectric grease for mainly keeping out the water and air. Fundamentally almost any grease or oil should not conduct electricity because the molecules are non-polar.

I bought a bottle of 3M grease (they call it silicon paste) from their online store. What I find interesting is that they say this stuff can also be used for brake calipers. It seems to work well enough for me as a dielectic grease. I have not tried it on anything else.

Ray H · Jun 20, 2004

quote:

Originally posted by rg144:
Also the old reliable Vasoline Petroleum Jelly. Cheaper than the stuff at the auto store to slather on the battery terminals to prevent corrosion.

You're on the right track, rg, but old, reliable Vaseline ("wiener schleider") Petroleum Jelly has much too low a melting point to be useful for the long haul in that application. Better old reliable generic lithium soap based chassis/wheel bearing grease is much more suitable because of its much higher melting point and clinging adhesion properties, and a tube is dang near as cheap, too.

RavenTai · Aug 16, 2004

quote:

Originally posted by Idrinkmotoroil:
yet the grease is not affecting the spark energy as it isnt that good of an insulator. Joey

Dielectric grease is a good insulator at all automotive voltages (including very high voltages found in the secondary ignition system), when you assemble the joint the grease is pushed out of the way so there is metal to metal contact (conductor to conductor), the grease is never part of the circuit, if it becomes one then you have an open circuit, it winds up in the same places as the original connector insulator, “air”

Displacing air in a electrical connector is a good thing; air brings water dust dirt and oxygen as stated above, also grease conducts more heat than air (air is also an excellent thermal insulator as well) keeping the connector cooler when it is at or near its current limit

What Benefit Does Dielectric Grease Provide !.....

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