I just pulled my stainless Bassett tri-y's off of a new motor wirh aluminum heads, motor has 30 hours on it and the headers have been on for 12 hours. I used nickle anti sieze on the steel cap head bolts that go into the steel adapter plates as well as the steel bolts going into the aluminum heads. The anti seize was much more dissolved and burned away than I had hoped it would be and one counters bolt holding the adapter on required welding a nut on to get out.

Is anyone aware of a better anti sieze for dissimilar metals and the high heat of a header? I read the anti seize thread and some others, but C5-A is the best option I've found, I think, so far. Has anyone been using it, something else.?

You used this one ?

Permatex 81343 - Permatex Anti-Seize Lubricant

* Temperature range: -60 to 1,600 degrees Fahrenheit
* Salt, corrosion, and moisture-resistant
* Ideal for marine use
* Use on any stainless steel nuts, bolts, clamps or other hardware to prevent thread seizure.

Ayuh,..... The absolute best antiseize I've found is plain ole Form-a-gasket #3,.....

Ive never used anti-seize on headers just spark plugs.......in aluminum heads

I use black socket head cap screws, grade 8 lock washers and Permatex #80078. Never an issue.
https://www.permatex.com/products/lu...ubricant-8-oz/

I’ll never forget my gpa getting me to start using this when I was really young. He swore on it and used it on everything. I’ve been using ever since. Works great.

Think we missed something important due to a typing error.

In bold above, was that supposed to be ‘counter sunk bolt’ ?

counter sunk allen bolt

I’ve never had an issue removing exhaust bolts but never used anti seize on them. With only 12 hours they should back out easily. What size allen on those countersunk bolts? I could see if smaller than 5/16 getting hogged out.

The anti seize should work fine in that heat range according to their claims anyway.