He got the MF's at Rock Auto for $2.50 each + shipping. It's a lot cheaper than what the 3/8 or 5/16 MF's cost. He got the lifetime supply.
Nylon should work fine ..or someone needs to tell all the man's to stop using it for engine internals. It handles high temps well...
While I have a ton of brass barbed fittings, and use them with full confidence, most in this size are only rated for 200F (or is it 212F?).
Here's the rating for a brass barb'd reducer coupling like in the image above. This is from McMaster-Carr, page 267. Not even 200F.
Shape
Coupling
Coupling Type
Reducing Coupling
Material
Brass
For Hose Inside Diameter
1/2" x 3/8"
Operating Temperature Range
-40° to +160° F
Maximum Pressure @ 72° F
250 psi
Vacuum Rating @ 72° F
Not Rated
For Use With
Air, Water
For Hose Type
Reinforced Rubber
Clamp With
Hose Ferrule, Worm-Drive Clamp
Specifications Met
Society of Automotive Engineers (SAE)
SAE Specification
Functional SAE J512 Requirement, SAE J476
one rated for 200F is $50 and is stainless steel.