I ran 1/2" aluminum tube to my oil drain off my turbo with a 1/2" standard brass flare nut (female). The flange off the turbo is -8 AN male. The flare angle on each peice appears to be 45 degree, but the surface of the AN fittings are longer than that of the flare tube fittings.

Is this okay or did I make a bad assumption of the mating abililty on these two fittings?

 

Auto AN fittings are 45 degrees. Aviation AN fittings are 37 degrees.

 

I took an old 45 degree set and had a friend with a machine shop cut it to 37* Works like a charm. I use aluminum hard lines with AN fittings a lot and like them. The key to longevity is to make sure that the tubing is supported properly.