The silicone tubing and couplers are not intended for coolant of oil lines! Do NOT try it.
The hoses you're looking at are used to prevent the throttle body and ISCV from freezing up (and NO, it doesn't have to be very cold out for this to happen). You may replace them with straight 3/8" (9mm) coolant hose but the stock lines wrap around a lot of crap so be careful to avoid kinking the hoses or putting them in in such a way that they may rub (good luck.
).