I need to get my /6 3.0L oil cooler modified with an AN or NTP fitting. Being that my oil tank is NPT - I would think that putting a 1" NPT fitting on the oil cooler is the way to go. But I see some people say they used -16 AN.

Does it really matter what type of fitting to use for this application?

Thanks.

I think that most people have been using the -AN fittings. As long as you can make up the required hose, it probably doesn't make a lot of difference as long as the internal dimensions of the fitting don't restrict oil flow.

Fitting type doesn't really matter. Given the option, I would pick AN fittings over NPT because they have the tendency to seal better and do not require swivel ends.

A NPT to -AN adapter fitting is pretty common so it doesn't really matter. What kind of hose will you be using? The sump to the engine is a suction side and regular hose could collapse, I'd make sure that won't be an issue.

Has anybody ever done a hose-barb fitting instead of a threaded AN? Kind of like what is already on the oil cooler now before the conversion? I'm looking into this as a possibility - it's the way it is on the 911 (and Porsche designed it that way, they know a thing or two) - why spend all that extra money on fancy hose and fittings since it's unpressurized?

I've seen hose fittings on a 911 cooler come off at the track
the threaded fitting is safer
the motor looses oil pressure pretty quick when the oil hose is off...

that being said many many cars survive with barb fittings.
but having seen one fail in person its not something I'm comfortable with.

I would put a fitting on the hose as it has to be removed (opened) to properly drain the oil for an oil change. The original -6 has threaded metric fittings next to the support bracket for this purpose.