Silicone will handle most oils/fluids but defo pas fluid, there is NO pressure in the tank/reservoir to pump feed, other than atmospheric, ie 14.5038psi, not exactly high pressure.
Failing that OPA will do the job as resistant to all oils, all petrols, and air pressures, burst pressure of 135BAR, 1958psi.
Cheap too, the last I bought was 17mm internal 1 metre long and £5.38 inc vat.
tabetha