Red Clay won't come off vinyl siding!

[Ptech84]

Hey guys, Im new to the forum, and ive been doing alot of researching. I cant seem to find a good answer to what will remove the red clay stains from vinly siding. So far ive used, F8 with no results, and F18 with alot of scrubbing and it just lightens the red stain but won't take it away.
Please if anyone can help I'd appreciate it!

[Ptech84]

I'm doing a tremendous amount of searching and reading and the only thing I have found so far is Muriatic Acid 10:1 out of a pump sprayer. Would that work or will it damage the vinyl? Can anyone either confirm or deny this?

[ambtink]

Are you sure it's red clay? Can you post a picture of it?

[HSPW]

F13. Gutter grenade.

[kiloman7]

Use truck wash acid much much better choice there are several places that sell it around here.

[Guy B]

Use truck wash acid much much better choice there are several places that sell it around here.

Yep! That's correct!

[Ptech84]

I'm positive its red clay. Its at the bottom of the vinyl and you can see where it has rained and splashed up on the siding.
The one thing I didn't try was the F13, Ill try a test spot.
So when you say truck wash acid, do you mean the Aluminum Acid Wash?

Thanks for the help guys.

[cmturner]

Oxalic acid normally does it for us, maybe the f8 wasn't mixed strong enough?

[kiloman7]

Yes ox might work but why waste time mixing a farting around straight in pump up works wonders.

[innovativewash]

Use a product called NMD 80 from Echo chem. Mix it 10-1 and pump spray it on let dwell for 8-10 min. Washes right off.