gtracer, this is an old thread, check the date!!!
since i posted, it has been about 7 months, and in that time, i have done maybe 7 thousand kays, and have come to the conclusion that the redline ultra lightweight is an excellent gearbox oil, and suited to an rb25.
i have had no frothing/heat problems, and after a few kays (say 1500) the shift is a million times better than it was before, no crunching anymore, ever.
Oh yeah, and in those 7 months, i also lost my license
so my car is now for sale, complete with the redline gbox oil