I have a mechanical oil pressure gauge with a long plastic tube and a t-piece to allow the connection of both the oil pressure light and the gauge to the engine block. I have three questions of this.

1. What thread is the standard oil pressure switch in the Ford Zetec block ?

2. The plastic tube keeps pulling out of the fitting, do I need to flare the end of it in some way so the olive provided works properly ?

3. The olive is a short / fat shaped cone at one end and tall / thin shaped cone at the other. How do I tell which way round it needs to go ?

All probably simple questions but I don't fancy oil p*ssing out behind the dash ! (in fact oil p*ssing out anywhere at all, but behind the dash would make a real mess).

thanks
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I think the one I fitted have a metal fitting that goes inside the plastic tube.

I don't know Zetecs but I suspect the thead will be NPT .