Basically anything that meets the GL-4 recommended spec.
If you're going with Redline, I've read that MT90, D4 or D6 are all acceptable.
Thanks Riz. Everywhere I looked everyone was saying the MT90, but when I went to Redline's website D6 was the only thing it was recommending. Putting automatic trans fluid in a manual trans feels weird. As long as this is okay I guess i go with the D6