Teflon tape on oil/engine fittings: thoughts?

The advice you're getting on the Van's forum is sound.  Do not, under any circumstances, use teflon tape on oil or fuel fittings.

When I disassembled my Kitfox project after buying it from its first builder, I found that the teflon tape he had used on a fuel fitting attached to the header tank had migrated over the end of the threads and was blocking part of the opening.

If this happens, you can't see it.  Best case, it causes a performance problem that's detectable before flight.  Worst case, it breaks loose in flight, blocks a fuel line or oil passage and your engine quits.

Sorry I can't post a photo; this forum doesn't allow attachments.

Thank you, sir. Do you use anything for thread lubrication/sealant?

I disagree.

What Eric Page describes above is bad technique - it is not the fault of the material.

I have used Teflon tapes for probably 30 years without incident. Too many users wrap the wrong way, use far to much, do not leave the first threads bare, use tape on fittings that should not be taped.

I have never used it but I believe there is a liquid Teflon that could be used by those unable to reliably use the tape.

Like so many tools/materials - faulty technique gives it a bad name, when the fault lies with the human not the product.

It's not so much that there is anything wrong with the proper use of teflon tape for one use but I've picked out many a thread of teflon tape left in the female threads of a fitting after dissassembly. Some can be almost invisible.

Once I started using PST paste I can say that I have no use for teflon tape near anything that moves. 

Ken

Bad technique!?!? As I wrote above, I've seen an example of the problems with Teflon tape with my own eyes, on my own airplane.  You are, of course, free to use what you like on your airplane, but please don't accuse me of bad technique for using a perfectly suitable alternative, and for following the guidance in AC 43.13-1B.

Quoting from paragraph 8-38. f. (page 8-21), "Do not use Teflon tape on any fuel lines to avoid getting the tape between the flare and fitting, which can cause fluid leaks."

So, flare contamination is a third potential problem in addition to the two I mentioned and the one Mr. Lehman pointed out, above.

I'm sure Teflon tape can work to seal a joint against fuel and oil leaks, and I'm sure joints have been successfully made with it.  The problem is that when it goes wrong, you can't see it because the fault is hidden, and unlike a paste sealant, Teflon tape can come away from the joint in homogenous pieces large enough to clog filters or small passages.  I stand by my statement that Teflon tape is not suitable for this use case.

There are a number of fuel-safe paste sealants available.  The Loctite PST products, Permatex 85420 Permashield Fuel Resistant Gasket Dressing & Sealant, or Gasoila Soft-Set Pipe Thread Sealant are a few examples.