Special char-set usage
Am I doing this right?

oclHashcat-plus64.exe -a 3 -m 100 -p : --session=05100218 --force -o "F:\hashcat\output\argentina_sha1_found.txt" --outfile-format=2 -n 40 --markov-disable --remove -u 250 --gpu-temp-disable -1 F:\hashcat\oclHashcat-plus-0.15\charsets\special\Spanish\es_ISO-8859-1-special.hcchr "F:\hashcat\hashes\hash.org\argentina_sha1.txt"

I know the file is an argentine hash file, so I am assuming Spanish, but I don't appear to be finding anything.
you are missing the mask
Thank you radix!

So like this? Because it doesn't seem to be working.

oclHashcat-plus64.exe -a 3 -m 100 -p : --session=05101333 --force -o "F:\hashcat\output\argentina_sha1_found.txt" --outfile-format=2 -n 40 --markov-disable --remove -u 250 --gpu-temp-disable "F:\hashcat\hashes\hash.org\argentina_sha1.txt" "F:\hashcat\rules\masks_rules\rockyou-3-3600.hcmask" -1  F:\hashcat\oclHashcat-plus-0.15\charsets\special\Spanish\es_ISO-8859-1-special.hcchr
UPDATE2: using a .hcmask file doesn't make much sense in this case (together w/ the spanish.hcchr file) since the mask inside the .hcmask file must refer to the spanish.hcchr file somehow... i.e. the masks need to use some ?1 .... but rockyou-3-3600.hcmask doesn't do that... it would be better to use -1 -2 in your cmdline and define them appropriately
UPDATE1: radix was faster, anyway my answer:

if you use -a 3 (mask attack) it would make sense to define a mask (see http://hashcat.net/wiki/doku.php?id=mask_attack )
e.g. ?1?1?1?1?1?1?1?1
otherwise where do you think -1 is used?
A *minimal* cmdline would be:
oclHashcat-plus64.exe -a 3 -m 100 -p : -1 spanish.hcchr sha1.txt --increment --increment-min 5 --increment-max 10 ?1?1?1?1?1?1?1?1?1?1
(you ofc need to replace the hcchr file and hash file w/ the path to your files - as in your example -)

Attention: Since the password might also be a mix of numbers / latin chars + spanish chars you may need to combine them in a custom charset or a hcchr file that includes all of them (see http://hashcat.net/wiki/doku.php?id=mask...rset_files )
Thank you for taking the time for me, philsmd.

That might be my issue since my character sets are just the latin charcters.
no, if you define -1 to use the spanish.hcchr and if you also use -1 in your mask *OR* if you use a hcchr that includes all chars you want to try... there is no fallback to latin characters

It only didn't work because you missed to specify the mask (and w/ hcmask it doesn't easily work because there is no link to you spanish.hcchr anywhere)

So having both -1 my_full_charsets.hcchr and a mask ?1?1?1?1?1?1?1?1?1?1 - maybe together w/ increment - should work
Thank you, this is my first time messing with character sets, hence my total ignorance.
this stuff is on the wiki
Yes, but I was a bit confused and needed some clarification, and I really appreciate it.