Car Dumping Oil on hot days?

[HLC]

Gday guys,

got a weird thing happening.

on these hotter days when ive gone for extended drives, once i park and go do whatever i do, i come back and my car has dumped considerable amounts of oil on the ground?

temp guage always reads in the N-O or normal so its not playing up. the oil guage is still in its usual spot in the cluster (dont even know what it measures?)

so i dunno? any ideas?
cheers.
henri