Thoughts on Dialectic Grease? (Page 1/2)
82-T/A [At Work] JUN 02, 12:52 PM
I'm curious on your guys' thoughts on the use of dialectic grease.

I have to assume it's a good thing to use, but I see all kinds of advice out there and I'm not sure what's legitimate or not. I do not have an electrical engineering degree. My CompSci missed all of the cool classes that might have taught me about this. I see some people say that you should just load up a harness plug / socket, saying that it will "improve conductivity." But logic would tell me, if it improves conductivity, then would it not increase interference between the plugs if it's literally now bridging the gap between the individual pins?

I see this everywhere, and it makes no sense to me. I would instead hypothesize that all it's doing, is filling a potential void with gel, which inhibits water intrusion, and prevents corrosion from dissimilar metals, or "galvanic" corrosion (I think it's called).

My daughter is going to be pulling the wiring harness, and snaking it around the engine with all the proper sensors and connectors, and I'd like to teach her what's legitimate, and not continue to perpetuate myths.


Thanks!!!
olejoedad JUN 02, 02:16 PM
Dielectric grease in an electrical insulator, designed to prevent electrical signal migration and is an excellent water repellant.

Put a dab of it on the weatherpak connector seals if you care to.
I do recommend it for grounds.

The stuff GM put in the C500 connector is amazing, and should not be cleaned out of the connector and replaced, it's still gooey after all of these years and can be reused with no issues.
82-T/A [At Work] JUN 02, 02:55 PM

quote
Originally posted by olejoedad:

Dielectric grease in an electrical insulator, designed to prevent electrical signal migration and is an excellent water repellant.

Put a dab of it on the weatherpak connector seals if you care to.
I do recommend it for grounds.

The stuff GM put in the C500 connector is amazing, and should not be cleaned out of the connector and replaced, it's still gooey after all of these years and can be reused with no issues.




Thanks Joe, any idea what GM originally used in those connectors?
olejoedad JUN 02, 03:40 PM
No
It's gooey, dark brown and really doesn't like to wash off.

Think tar, and you would be heading in the right direction.

Since your not doing an engine swap in your daughter's car, there is really no need to mess with the C500 connector.
RWDPLZ JUN 02, 06:33 PM
I would use dielectric grease on any terminals exposed to the elements, like the exposed parts of the headlight bulb terminals.
theogre JUN 02, 07:14 PM
1. Remember "Water" is often very polluted w/ road salt & way worse things that corrode the connectors...
2. Up until the 70's Many parts in the engine bay & most still got installed Dry or bare minimum of protection & parts rot like old generators & alternators w/ external regulators.
3. Do Not believe most "data" that often came from the "PC world" (including the magazine) that uses "Arctic Silver" & worse products like "Liquid Metal" containing Gallium etc that Attack Aluminum.

GM et al use a thick grease since 50's or 60's typically called "Bulb Grease" to keep out "water" because even @ high temp @ the base of a light bulb the grease won't run separate etc. Bulb Grease is very likely Cosmoline still use by U.S. Mil for ~ 100 years now. You does need to clean it off normally. If have Skinned over w/ dirt etc then scrape the skin away before you push the dirt in whatever. This is often "better" then Weather Pack & more "water proof" plug systems but takes time & makes a mess dealing with it @ car factory so didn't use that everywhere.

Dielectric Grease is just Silicone Oil w/ Silicone Solids & few other additives. This can & will separate even in the package even @ "room temp" but slower.
Note: White Heat Sink Grease/Compound is Silicone Oil w/ Zinc Oxide to replace Silicone Solids to move heat better the DG but often does same thing w/ the oil but unlike most in the PC world say does nothing when dry, real engineers know not true & why many things still use this grease. Do Not use any thick grease on big parts like DIS ICM/PIM as surface can deform before spreading the paste.

DG itself is near Inert & electrically insulating but fills small gaps when metal touches or rubs on each other but often doesn't last long dealing w/ hot wet places like any engine bay. DG does Not help a connection to be "Better" when installed but keeps moisture out that Starts most types of corrosion. You need electric insulation so doesn't short 1 pin to the next unlike some other greases that may not cause a "dead short," can carry enough electric to totally F'd things like the ECM/PCM trying to "read" the sensors.

That's said, I keep pushing Permatex Green label Brake Grease because is Plastic/Rubber Safe & won't run or wash off easy when used things like ground bolted to the block. This does Not have silicone oil & never dry out even in/on the engine except on exhaust parts. I use this on DIS ICM because thin enough to flow out to move heat & keep out "water."

Weather Pack et al on Paper may seal for Decades but have many problems like have a wire pulled "sideways" @ the back often "leaks" to let "water" in the connector then rot often quickly. If you have problems like that, a very thin coat of silicone or permatex brake grease does work even here but may need special tools to get some apart. Too much grease can "blow out" of the connectors.

Example: Many put silicone on spark plug boots but they stuff the boot w/ too much, grease expand & boot pull the wire off the plug @ minimum. Worse can push the boot all the way off the plug cause very big problem burning dist cap & rotor, fry ignition coil(s), etc.

Weather Pack Et Al are Not "Water Proof" but "Weather Resistant" @ Best & never made to have a car driven in deep water. Bulb Grease etc won't help you for that too. "Deep water" for most cars are only 4" to 6" deep but Many SUV & "Crossovers" are in same category but fools thing the water isn't getting inside then safe to drive... That's often starts problems because "water" is force inside many ABS and other sensors.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

skywurz JUN 03, 12:35 AM
So is the stuff packed into the C500 Cosmoline? Like Cosmoline 1060 wax/grease?

[This message has been edited by skywurz (edited 06-03-2024).]

82-T/A [At Work] JUN 03, 08:28 AM
Thanks guys, I appreciate it! Biggest thing I wanted to get out of this was that dialectic grease is NOT conductive... which was a huge concern for me (because I heard a lot of people say that), and in fact, all it does (well, it's purpose) is to prevent corrosion and water intrusion. Which is super important to me, and I will heed that advice.

Before I go "ape" with the dialectic grease...

Ogre... when you said, "That's said, I keep pushing Permatex Green label Brake Grease because is Plastic/Rubber Safe & won't run or wash off easy when used things like ground bolted to the block." Where specifically did you mean you use this? Externally on the block grounds, or are you saying you pack the weather-pack connectors with this?




Is this what you use as a replacement instead of the stuff that Joe mentioned that came from the factory in those connectors?


Joe, on removing the C500 block. My daughter is going through the entire car, completely. It's got over 200k miles an we're going through everything... in part because she wants to learn as much as we want to completely re-do the car so she has a "new" car. So, we'll be going through that too. The car is faaaar too old and beyond the point at which we would "fix things as they break." The car needed a complete tear-down and restoration... which was kind of the goal. I haven't done the electrical yet, but I intend to make sure we use the grease liberally.


Thanks!
slicknick JUN 03, 08:45 AM
The wiping action of the connectors will make the electrical path regardless of the dielectric grease. The grease is there to keep everything else out. If the grease makes the connection worse, it was bad in the first place.

That being said, any modern sealed connector wouldn't need it. The proof is in the pudding, go to any junkyard and take apart a weatherpak or metripak connector. They're all fine.

I'd be hard pressed to believe the stuff in a C500 connector is cosmoline. That dries to a hard wax and is miserable to remove. Old school bulb grease does kind of remind me of the stuff. Like molasses.

Either way, the majority of these cars aren't getting beat on like they were in the 80's/90's, going through multiple winters and never being washed, so you're probably fine with less extreme measures.

(or replace all of that 80's stuff with sealed connectors. I did that on my S-10)
olejoedad JUN 03, 10:44 AM
I can tell you with great confidence ( from having pulled apart and repinned dozens of C500 connectors ) that there is absolutely no need to do anything in that area of the car except inspect the wiring for cracks and clean the exterior of the connectors.

!!NEVER!! pack a weatherpak connector with anything! If you want to do something, put a tiny bit of dielectric compound on the rubber seal and on the wires where they enter the connector.