I, too, was swayed by the product labeling and confident swagger of the parts counterman. Marketing and sales got the job done. But, the product did NOT work where I needed.
The S/G (syl-glyde) may provide some lubricative properties at 600 F from its added silicone. But, its carrier base will phase change well below that and lose it's base physical properties as a grease.
The Dow Stuff you listed is what you want, as you don't need lubricative properties at high temperature for this application, you need an environmental barrier for the metals behind the friction component that can perform this task at high temperatures.
Take a look at the TDS (Technical Data Sheet) for the Dow product. Seems unworldly.
Bleed: 200C <.5% (use a thin coat and it wont run away <- my comment)
Melting temp: None (highly desireable for this application <- my comment)
Chemical resistance (See PDF, but it's impressive <- my comment)
Solubility: (None really, can be dispersed, though <- my comment)
(How do you suppose they make this stuff?)
Anyway, after my debacle experience with S/G running into and ruining my brake pads, I placed a small sample of each product on an aluminum tray and positioned it in my gas fired oven. I increased the temperature in 50 degree F increments with a 5 minute stabilization period.
I published a report of the test to the SOHC4 mail list many years ago. But, I can't find it anywhere now. So, from memory...
At about 200 degrees the S/G began to liquefy and puddle. At about 300 degrees it began to smoke and the edges turned dark brown. This change progressed until the remaining deposit looked like the burned grease deposits on the back of a well used frying pan, though it did glisten and look "oily". I assumed the small silicone content survived the base carrier product destruction.
I continued the test waiting for the Dow product to change. Sure enough at about 450 degrees it began to glisten...I think. When I got to my oven and temperature probe's limit of 550 degrees F, the Dow product looked like a slightly shinier lump than when first placed in the 100 degree stabilized oven.
I then cracked the oven door open and prodded each sample with along piece of Stainless steel safety wire. The oven lost about 50-100 degrees during this test. The S/G was a hardened brown deposit on the aluminum that still appeared shiny. The Dow product still pushed around like a grease and left lumpy grease deposits on the wire as it did at room temperature.
After this test, I was confident about using it on my caliper and behind my brake pads, where it has stayed put and performed as required without contaminating my brake pads. I might note here that the grease I cleaned off the caliper (first rebuild after Honda production) looked exactly the same as the Dow Product.
At the moment, the nicest thing I can say about Syl-Glide is that it didn't leave an odor and taint the flavor of food cooked in the test oven afterward.
The Copper grease you listed is :
"Blend of fine, particle-size metals dispersed in a synthetic grease, designed to withstand very high temperatures and extreme pressures. It is particularly effective for use on bolts both for assembly and disassembly and where metal parts rub together." I think that last bit was added by marketing and sales to attract a wider buying audience. But, it was originally formulated as a bolt thread anti-seize, and I expect it would work fine for that application.
I could find no TDS for this product, only an MSDS. As it is a petroleum based liquid, however, I don't see how you will keep it in place and away from the brake pad rotor contact area.
I would not chose this product for the preservation of the caliper body, piston, and brake pad backing on SOHC4s.
Feel free to experiment and post results.
Cheers,
