/u01 should be root:root.
/u01/app should be root:root.
I don't know why your top-level directory has oinstall as the group owner. That just seems wrong. I ran some tests and it allows grid to change and delete other people's directories located under /u01.
I recommend you change ownership of /u01 to root:root. Do not use the -R option because you don't want to mess up the sub-directories.