Spark Plug Paste

As some people know, Rotax / BRP request in the shop manual to install spark plugs using a paste for better thermal conductivity.

Curious, I found this You Tube video comparing copper anti sieze against thermal pastes used in computer electronics. This is not comparing the specific Rotax / BRP thermal paste, but certainly demonstrates that copper anti sieze is a very good thermal conductor.

I realize that BajaRon does include a thermal paste with spark plugs purchased from him.

This is a For Information Only topic and not endorsing Copper Anti Sieze or BajaRons thermal paste.

https://m.youtube.com/watch?v=RFtvmxE6umA

This video compared copper anti sieze vs a Radio Shack brand thermal conductive paste.

https://m.youtube.com/watch?v=U39y-zl-6X4

Seem to remember it being said NOT to use any kind of anti sieze paste when installing new spark plugs...:dontknow: Does the copper make it OK to use ??? Thanks for the links and the info..:bowdown:

BajaRon ships thermal paste with his spark plugs. This must be a different consistency from anti-seize paste.

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Originally Posted by Chupaca

Seem to remember it being said NOT to use any kind of anti sieze paste when installing new spark plugs...:dontknow: Does the copper make it OK to use ??? Thanks for the links and the info..:bowdown:

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The type of Anti-Seize paste is critical ….. it MUST be the Copper version ...it is for High Heat applications ….. I have been using it on my Spark plugs for a few decades now …. I was advised to use it by a Master Mechanic ,,,,,, As Paul pointed out it works for Spyder plugs ….. Mike :thumbup:

Interesting video there.

Anti-seize is typically described as an insulator. Though with metal properties (Aluminum, Copper, etc.) it would make sense that there would be some heat transfer capabilities. I think the difference is in the efficiency factor. Anti-seize is not primarily designed to transfer heat. Thermal paste is.

Copper absorbs heat better than aluminum. But aluminum releases heat more readily than does copper. That is why you will find copper core heat sinks where copper is the metal touching the hot surface (as well as the heat tubes if it has them). With aluminum surrounding the copper components and aluminum fins to release the heat.

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Originally Posted by BajaRon

Interesting video there.

Anti-seize is typically described as an insulator. Though with metal properties (Aluminum, Copper, etc.) it would make sense that there would be some heat transfer properties. I think the difference is in the efficiency factor. Anti-seize is not primarily designed to transfer heat. Thermal past is.

Copper absorbs heat better than aluminum. But aluminum releases heat more readily than does copper. That is why you will find copper core heat sinks where copper is the metal touching the hot surface (as well as the heat tubes if it has them). With aluminum surrounding the copper components and aluminum fins to release the heat.

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Awesome answer that begs more questions.

Is thermal paste a good anti sieze compound on threaded high temp fasteners?

The description of the copper core heat sink is sounding very similar to using copper type anti sieze on threads of spark plugs. The copper has the ability to surround the hot material with aluminum in contact with the copper and radiating the heat away.

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Originally Posted by PMK

Awesome answer that begs more questions.

Is thermal paste a good anti sieze compound on threaded high temp fasteners?

The description of the copper core heat sink is sounding very similar to using copper type anti sieze on threads of spark plugs. The copper has the ability to surround the hot material with aluminum in contact with the copper and radiating the heat away.

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Interesting point about the transfer efficiency of pulling heat from the steel spark plug threads with Copper and then to the Aluminum heads. But with modern day spark plugs, the need for an anti-seize compound is much smaller than it was when aluminum heads first came out and people were pulling the head threads out with the spark plugs.

Spark plug makers have engineered modern steel spark plug threads with coatings that resolve the dissimilar metal issues created in the beginning. Though thermal paste is not primarily designed as an anti-seize compound. It provides more than sufficient lubrication to prevent any galling or seizing of the threads.

The whole idea with thermal paste is to fill the voids between the thread to thread contact areas (spark plug to head interface). By filling these voids with a heat transfer agent, it greatly increases the surface area through which heat can be dissipated. Thus greatly increasing the volume of heat which can be moved from the spark plug to the heads.

I also use the copper anti-seize ( very sparingly ) on my Oil Plugs ….. no issues there either …………..Mike :thumbup:

After even more internet searching, and reading, it seems the Wacker P12 Thermal Paste is a silicone grease type product. It has very low electrical conductivity and is termed as electrically insulating. Pasted below is the tech sheet.

At this point, it seems Rotax uses this paste in all their 4 stroke engine spark plug installations. Two stroke engines are not using the thermal paste. I have no idea why, knowing two strokes can go rogue from maverick spark conditions.

Apparently the paste does have a shelf life or use before date criteria. Seems odd since silicone grease is one of those forever products.

Seems then, for those buying spark plugs from BajaRon, he includes the paste, it is a good match for owners changing spark plugs.

http://sdb.wacker.com/pf/e/result/re...=7370&P_SPEC=R

From reading the tech sheet regarding the Wacker P12 thermal paste, the intended application is for electronics.

The intended method of application is a thin coating, however, the type of installation from what is recommended by Wacker vs Rotax deviates. Wacker is intending the application to be a thin layer in a fayed type joint. Rotax is using the thermal paste in a threaded joint.

No doubt the Rotax engineers tested the application with elaborate testing of actual temps. The primary question is not whether thermal paste performs better than dry threads, certainly it must. Rather is it significantly better than copper based anti sieze.

Sadly, my linked videos did not test Wacker P12 specifically, but did test some high end products, likely superior to the Wacker P12. There are other test data published. Entirely up to the user, just sharing what I have researched prior to my own spark plug change.

A good read, the numbers for copper are impressive. The key though, is ensuring whatever is used is not wiped away or insufficient.

https://www.ekwb.com/blog/thermal-compound-guide/