If any one of them shows visible damage, replace the cap with a new one.

NOTE
Wet the cap sealing surfaces with water or coolant to prevent pressure leaks.

Radiator Cap Relief Pressure Standard: 112 ∼ 142 kPa (1.14 ∼ 1.45 kgf/cm², 16 ∼ 21 psi)
If the cap can not hold the specified pressure or if it holds too much pressure, replace it with a new one.
Radiator Inspection
Radiator Filler Neck InspectionReporting safety defects
(For Products Sold in the United States of America, District of Columbia,
and
U.S. Territories Only)
If you believe that your vehicle has a defect which could cause a crash or
could
cause injury or death, you should immediately inform the National Highway
Traffic
Safety Administration (NHT ...
Oil Pressure Relief Valve Inspection
Remove the oil pressure relief valve (see Oil Pressure
Relief Valve Removal).
Check to see if the valve [A] slides smoothly when pushing
it in with a wooden or other soft rod, and see if it comes
back to its seat by spring [B] pressure.
NOTE
Inspect the valve in its assembled stat ...
Storage
Preparation for Storage
Clean the entire vehicle thoroughly
Run the engine for about five minutes to warm the oil, shut it off, and
drain the
engine oil.
WARNINGEngine oil is a toxic substance. Dispose
of used oil properly. Contact
your local authorities for approved disp ...