Quick Newbie question

[Shin0bi]

I'm getting set to attempt my first oil change in my 300zx Fairlady.It's got approx 140k km on the engine, so I am thinking a synthetic oil is going to be my best bet.

Would anyone recommend a specific brand or format of oil? I hear Royal Purple is good stuff but a bit on the pricey side.

Also, an issue I've noticed is that if my car is in neutral or in first with the clutch down, the revs slowly die down until the car just kind of sputters out. But the wierd thing is that it only does that while the car is still cool. once I've been driving it around for a bit, that doesn't seem to be an issue, and it idles nicely at around 1200 rpm. Any thoughts on why this could be happening?

[NolimitZ32]

mobil, castrol, royal purple, amsoil (although i've heard horror stories from VW guys about it)

your car is supposed to idle at around 700 so 1200 is way high, as far as the sputtering issue i think you just need to go through and clean everything, change plugs and go from there, it could be a problem of dirty air/fuel passages/injectors or a sticking iacv or it could be something way worst but you wont find out until you get all the maintenance out of the way.