Anti-seize for stainless bolts into aluminum threads

[oil pan 4]

Seems like my fav, copper anti-seize isn't ideal for this.
I'm thinking my options are:
Nickel anti-seize
Molybdenum disulfide and graphite dry lube spray on the bolts

 

[Nessism1]

What's wrong with copper? I thought that was prefered? Regardless, just use something. Some formulas are better than others, but that's important is to just use some.

 

[jadmt]

I have used both copper and silver anti-seize for years on stainless to aluminum without issues

 

[Propflux01]

I use Nickel Never-Sleaze.

 

[Astro14]

Regular antiseize. Steel bolts in an aluminum subframe. Stainless steel spacers.

Epic galvanic corrosion.

Bolts broke right apart. Spacers were filled with aluminum oxide to the point where they were bonded to the subframe and it took a pipe wrench to break them free.

Induction heater and stud remover to get the bolt remnants out.

 

[Sequoiasoon]

View attachment 322854Regular antiseize. Steel bolts in an aluminum subframe. Stainless steel spacers.

Epic galvanic corrosion.

Bolts broke right apart. Spacers were filled with aluminum oxide to the point where they were bonded to the subframe and it took a pipe wrench to break them free.

Induction heater and stud remover to get the boot remnants out.



View attachment 322853

So what would be the recommendation for correct stuff to use?

Fluid film before and after? Blaster shield?

 

[MurkyAsparagus]

This is a pretty common occurrence in marine applications that use 316L stainless hardware and aluminum blocks/manifolds/other stuff. They always use Never-Seez Mariners Choice or Loctite Marine Grade Anti-Seize.

 

[Number_35]

View attachment 322854Regular antiseize. Steel bolts in an aluminum subframe. Stainless steel spacers.

Epic galvanic corrosion.

Bolts broke right apart. Spacers were filled with aluminum oxide to the point where they were bonded to the subframe and it took a pipe wrench to break them free.

Induction heater and stud remover to get the boot remnants out.



View attachment 322853

Do you think the regular anti-seize made things worse, or only failed to help?

 

[Astro14]

Do you think the regular anti-seize made things worse, or only failed to help?

I honestly don’t know. When I put it back together, I used nickel antiseize, stainless bolts, no spacers. I’m not sure if that will help. The car is in Vermont. Tons of salt. So, potential galvanic differences are exaggerated.

 

[Pablo]

I use Nickel Never-Sleaze.

Absolutely. Nickel.

 

[oil pan 4]

What's wrong with copper? I thought that was prefered? Regardless, just use something. Some formulas are better than others, but that's important is to just use some.

After years of working with stainless steel on stainless steel nuts and bolts I can say for sure my preferred is copper antiseize.
Stainless steel hardware on steel structure, copper.
Stainless steel and steel mixed hardware, also copper.

This application is solar panel racking.
Why I decided copper may not be the best choice:
There's a 6 gauge solid bare ground wire that run to each aluminum rack row. It appears the copper and aluminum are attacking each other and the stainless bolt is just sitting there watching, laughing at the aluminum and copper duke it out.

 

[novadude]

I was always taught that stainless capscrews and aluminum threads are a bad idea, due to galvanic corrosion. A zinc-aluminum flake coating on the capacrew is a better choice, IMO. This is the dull silver coating you see on many of the bolts the OEMs are using these days. You can buy this coated hardware through McMaster, etc.

 

[oil pan 4]

I was always taught that stainless capscrews and aluminum threads are a bad idea, due to galvanic corrosion. A zinc-aluminum flake coating on the capacrew is a better choice, IMO. This is the dull silver coating you see on many of the bolts the OEMs are using these days. You can buy this coated hardware through McMaster, etc.

Just rain falling on the stainless steel bolt and aluminum threaded joint over 5 years almost nothing has happened. But, I can see the top few threads of aluminum starting to corrode, or looking like they want to corrode.
I want to be able to take these apart 10 to 20 years from now and reuse or sell them.
I've already got the stainless steel hardware so I'd rather not replace it.
The zinc-aluminum coated steel appears to be a cheaper alternative to stainless.

 

[LouC]

The problem with regular antiseize is that the copper is more noble than the aluminum and in the presence of moisture can cause galvanic corrosion, commonly seen on aluminum marine engines, outdrives and outboard lower units.
With non-high temp applications I have used OMC/BRP gasket sealer or Permatex Aviation on stainless bolts going into aluminum castings and even on an aluminum outdrive that spends 5 months in salt water, the bolts come right out. I used them on a thermostat housing on the 4.3 Chevy in our boat and also on exhaust manifold bolts (these only get to about 150-170* so not a true hot applicaiton) and they ALL come out easily. Want proof? Here's an aluminum outdrive used in salt water, it is moored in the water 5/6 months each year. Some of these bolts were last installed in 2006, that's right. When I removed them to replace a bad water pump shaft seal they ALL came out, easily. So that's what I do.....both the bolts holding in that plate and the plate itself were in there since 2006, the last time this repair was done. To my great pleasure all the bolts came out and the plate was easy to remove once 3 holes were tapped so grade 8 bolts were used to push it off of the upper gear housing. The edges of the plate and o-ring around that circular plate get coated in the same gasket sealer. What makes things get stuck is galvanic corrosion and also calcium deposits from salt water. Now guys on other boating boards have fought with this repair for days, it literally took me all of an hr at most, including tapping the 3 holes.
So OMC/BRP/Evinrude gasket sealer, is the best, but very hard to find now, Permatex Aviation Sealer works just about as well. For very hot applications I'd use antiseize for aluminum, they do make it.

PS I also use the gasket sealer on our 3 Jeeps on suspension and brake bolts, these all get driven on the beach in summer.

 

[LouC]

The other option in a pinch is you can use a good marine grease like Lucas Marine (blue) grease.

 

[AdmiralYoda]

Oh no....you just messed up my plans! I'm mentally preparing to rebuild my old Toyota 22RE and for cosmetic reasons was planning to use Stainless bolts for everything on the engine. Cast iron block but aluminum intake, cylinder head and timing cover.

What about a stainless bolt that goes through an aluminum timing cover into a cast iron block?

 

[thescreensavers]

I bought 8oz of CRC SL35911 Nickle anti-seize in 2015, still have plenty of it left.

 

[oil pan 4]

Oh no....you just messed up my plans! I'm mentally preparing to rebuild my old Toyota 22RE and for cosmetic reasons was planning to use Stainless bolts for everything on the engine. Cast iron block but aluminum intake, cylinder head and timing cover.

What about a stainless bolt that goes through an aluminum timing cover into a cast iron block?

If the stainless steel bolt is going into aluminum structure you can still use copper it's just not ideal.
These joints on the solar panel racking are exposed to the elements.
So stainless bolt, into aluminum threads with cooper anti-seize add rain and something is going to happen between that copper and aluminum I'm already seeing that where the copper ground wire touches the aluminum. If it never gets wet, nothing is going to happen.
As long as water doesn't get down into the threaded area it should be fine.

 

[RooflessVW]

Oh no....you just messed up my plans! I'm mentally preparing to rebuild my old Toyota 22RE and for cosmetic reasons was planning to use Stainless bolts for everything on the engine. Cast iron block but aluminum intake, cylinder head and timing cover.

What about a stainless bolt that goes through an aluminum timing cover into a cast iron block?

I would forgive stainless bolts entirely and use zinc plating or painting for your hardware.

 

[Gus_Mahn]

I’d look to marine parts supply for the answer. Something like this
https://www.westmarine.com/tef-gel-corrosion-eliminator-and-anti-seize-lubricant-2-oz.-12222220.html