How to check engine vacuum hoses<br>Check each hose for bulges and swelling. If a hose feels soft or spongy when you touch it, this can indicate damage caused by your car's oil. [substeps] A swollen hose that is cracked and hard is often caused by heat damage.
Oil leaks cause damage to hoses
The context did not say anything about leaks. It only mentioned that oil can make the hose soft and spongy. That texture is not necessarily the result of an oil leak. 
( z1 cause :ARG0 ( z2 leak :ARG1 ( z3 oil ) ) :ARG1 ( z4 damage :ARG0 z2 :ARG1 ( z5 hose ) ) )