tranny to cooler quick connect was leaking so i cut steel line and replaced it with high temp/pressure silicone hose made by flexfab. i know i should use hydraulic line, but how resistent to tranny oil is silicone.

 

NOT at all. Unless it is Flourocarbon Lined Silicone. We are developing some but it is not ready for market yet.

I would change that line soon. Silicone is not suitable for any petroleum products. It will handle spray or residue from the engine bay but will break down rapidly when used as an oil line or similar line.

 

the napa gold oil filters use silicone antidrainback valves.....its been on now for about 3 weeks now, pulled it to check it and it looks fine. the dude at the auto supply said this hose should be fine. this is no puny hose by the way it is double lined blue outer with a reddish inner. its silicone heater hose 250 psi/350 degree.

 

Checked flexfab's material data sheet. They even state "very limited, or completely unsuitable" for petroleum based oils and lubricants.

We make a lot of silicone products our heater hose has similar specs. But unless it is flourocarbon lined it is not suitable for petroleum products. Transmission fluid is petroleum based is it not.


Transmission fluid basic ingredient:
OIL PETROLEUM DISTILLATES, SOLVENT-DEWAXED HEAVY PARAFFINIC

Our material data sheet for Silicon hoses and Tubing:

Silicone Tubing and Hoses
Advantages:
Excellent biocompatibility; no leachable additives, DOP, or plasticizers; odorless and nontoxic, fungus resistant. No taste imparted to transported fluids. Extremely good at low temperatures. Weather, ozone, corona, and radiation resistant. Minimal tendency to take a set.

Limitations:
Do not use with concentrated solvents, oils, or acids. Relatively high gas permeability.

Application Suitability:
Acids: Poor
Alkalies: Poor
Organic solvents: Not recommended
Pressure: Fair
Vacuum: Good
Viscous fluids: Fair
Sterile fluids: Excellent
Physical Characteristics and Composition:
Thermal set rubber. Siloxane polymers and amorphous silica. Excellent compression strength. Soft material. Translucent, clear to light amber.
Temperature Range:
-60 to 460°F (-51 to 232°C)
Meets Classifications:
USP Class VI FDA 21 CFR 177.2600

 

thanks, ill be changing it soon.