[ranisron]

on a stock KA higher octane doesn't make much of a difference (hence switching around won't cause any problems). Some of us here are quite anal putting higher octane gas into the 240sx since on your gas door it says "premium gas for performance". This whole debate can go on for ever... so... it's all up to you.

I haven't touched 87 octane for a LONG time - I'd say put at least 89 octane for good performance/reliability even though our cars are made to run 87 octane - afterall the difference in money you spent on gas is NOT that significant.