Teflon tape on oil/engine fittings: thoughts?

I don't usually use Teflon tape on any of our fittings. When installed properly I have never had a leak. That said there have been a few times under specific conditions I have use a product call Hylomar (blue). It's in a tube and works very well and is specified for things like fuel gaskets and can be used on threads, but like they said above improper use of anything can cause an issue. Using Teflon tape in the wrong place like the oil pressure sender on the oil pump doesn't need it because of the thread type, but some senders like the VDO 360-004 SINGLE wire sender gets its ground from the engine and applying something of the wrong type or wrong way will cause a poor ground connection on the threads.

Hi All

On any fitting that uses an AN fitting, the 37 degree mating surface, never use tape.  The seal is done by the contact and pressure on the 37 degree face and not on the threads.  Vans uses all AN fittings which is aviation standard.  I would follow the Vans documentation always. 

Sealing tapes or liquids are for threaded fittings not for angle ones.  (SAE taper fittings are 45 degree and not aviation standard and even there no tape is used)  I am pretty sure the metric taper fittings are also 37 degree the difference is the  threaded parts are not standard but metric.  

For the threaded portions of a fitting that make contact into a casting use the recommended torque and liquid called out from the OEM. 

Cheers

Rotax Wizaed - not all fittings that may require sealing (prevent liquid/gas escaping) are AN or SAE.

It is these screws/bolts that may benefit from an appropriate and correctly applied seeling substance.

I have little doubt, that the origional enquiry from Steve Kessinger, related to  fixings in this category