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calling sl6 dan the old dielectric grease discussion .
https://slantsix.org/forum/viewtopic.php?t=57890
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Author:  bob fisher [ Mon Jun 15, 2015 8:41 am ]
Post subject:  calling sl6 dan the old dielectric grease discussion .

looking for uncle dan our sage of electrics- recalling last falls discussion on this point, i read an article which said moly grease, actually molybdenum disulfide which i have used to grease front end suspension joints , is best for corrosion prevention on auto electric connections and house wirenutted connections. the reasoning is that this kind of grease has graphite in it which is conductive and not dielectric so it will not impede current flow. like all grease films it will slow moisture and corrosion. did not know that graphite was conductive - is this true? seems you want an anti corrosion protectant on electricals which is also conductive. i know uncle d advised that dielectric grease is ok for this purpose . no oxy is a black grease just like moly- wonder if it is the same thing. by the way pop and uncle earl since the 40s always swore by petroleum jelly on the battery terminals. why was this done. seems to me pj would be bad not only b/c it is dielectric but also because when the weather or engine gets hot, it melts away and slobbers over nearby surfaces. dont see it used anymore. thanks tons bob f

Author:  SlantSixDan [ Mon Jun 15, 2015 8:54 am ]
Post subject:  Re: calling sl6 dan the old dielectric grease discussion .

Quote:
i read an article which said moly grease, actually molybdenum disulfide which i have used to grease front end suspension joints , is best for corrosion prevention on auto electric connections and house wirenutted connections.
Oy. No. Use the right tool (or material) for the job at hand. Molasses, ketchup, chassis grease, shampoo, peanut butter, floor wax, pure maple syrup, maple-flavoured pancake syrup, and Elmer's Glue-All each have many wonderful properties, and may inhibit corrosion to some degree on electrical connections…but none of them is the right material for the task, and some of them aren't compatible with other materials used in and near wire connections.
Quote:
the reasoning is that this kind of grease has graphite in it
No, graphite grease has graphite in it. Moly grease has molybdenum disulfide in it.
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which is conductive and not dielectric so it will not impede current flow
Dielectric grease, properly applied to a properly-assembled electrical connection, does not impede current flow. A shoddy connection impedes current flow with or without any type of grease.
Quote:
did not know that graphite was conductive - is this true?
Yes, graphite is conductive. So is molybdenum disulfide, though to a lesser degree.
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no oxy is a black grease just like moly
Ox-Gard, NoAlOx, etc. are greenish greases that contain zinc and sometimes graphite.
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pop and uncle earl since the 40s always swore by petroleum jelly on the battery terminals. why was this done.
To inhibit corrosion of the battery terminals. It works, though there are better and more heat-resistant options.
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seems to me pj would be bad not only b/c it is dielectric
How do you figure this is bad? It's not.

Author:  bob fisher [ Mon Jun 15, 2015 11:11 am ]
Post subject: 

hi danno- wow thats the first time ive heard the exclamation oy since uncle moe used to say it back in 68. like being in cuba and saying ai caramba! think im going to rely on dielectric and no oxy grease for beating corrosion on electricals, just make sure the connections are tight and clean. will leave moly for the ball joints. never heard of graphite grease- good for electricals? take care uncle d . bob f

Author:  '67 Dart 270 [ Mon Jun 15, 2015 12:16 pm ]
Post subject:  Dan is the electron man...

Dan is correct, the whole reason for dielectric grease is to protect the connection from moisture (and e.g. lubricate the connection so you can get that boot off with the plug wire still in it).

Dielectrics are insulators, they play no part in the electrical connection, they are there to stop corrosion and perhaps as a lube for sticky connectors.

Graphite and moly disulfide are, besides being fantastic lubricants and having excellent thermal and mechanical stability, are both electrically conductive. I would not use these on electrical connections, as they are not needed to make the electrical connection, and if they ooze out, will potentially short to other stuff (ground or other connections (e.g. on the fire wall connector block connections (some people grease these connections)).

Brian

Author:  '67 Dart 270 [ Mon Jun 15, 2015 12:29 pm ]
Post subject:  ...a little chemistry...

Dan is also correct that petroleum jelly and the things folks used to use have been replaced with dielectrics that can take higher temperatures, have more stability and can resist high voltage sparks. So, when you buy a high quality dielectric grease, it may look like PJ, but it isn't, it's very likely silicone grease.

Here's the chemistry bit, moly disulfide (the disulfide part) though pretty unreactive generally, may react with gold connectors, potentially eating up the gold plating. Disulfide is an excellent coordinator with noble metals.

Brian

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