AX-15 oil

Would it be a bad idea to mix redline oil with syncromesh, or better off to just run the redline oil? Im having some problems getting it into gear sometimes, dont know what the owner before me used.

I would use one or the other don't think I would mix 2 kinds together had to have my ax15 rebuilt because the wrong kind of gear oil was used GL4=bad for ax15.

I use the Redline MT-90 and it shifts very smooth now, it shifted so much better the first time I drove with the MT-90 in it and even better after I flushed it out again. the last owner filled it with some GL-5 gunk.

~Alex