You do not have sufficient permissions to access the inventory '/u01/app/oraInventory'

[gguser@Linux03 Disk1]$ ./runInstaller

You do not have sufficient permissions to access the inventory '/u01/app/oraInventory'. Installation cannot continue. It is required that the primary group of the install user is same as the inventory owner group. Make sure that the install user is part of the inventory owner group and restart the installer.: Permission denied

[gguser@Linux03 Disk1]$ ls -ll /u01/app/oraInventory
ls: cannot open directory /u01/app/oraInventory: Permission denied

CHECKING THE GROUPS ON oraInventory:

[root@Linux03 Desktop]# ls -all /u01/app/oraInventory
total 28
drwxrwx---. 5 oracle oracle   4096 Feb 29 15:24 .
drwxrwxr-x. 7 oracle oinstall 4096 Apr 13 14:40 ..
drwxrwx---. 2 oracle oracle   4096 Feb 29 15:24 ContentsXML
drwxrwx---. 2 oracle oracle   4096 Feb 29 15:21 logs
-rw-rw----. 1 oracle oracle     54 Feb 29 15:24 oraInst.loc
-rwxrwx---. 1 oracle oracle   1612 Feb 29 15:24 orainstRoot.sh
drwxrwx---. 2 oracle oracle   4096 Feb 29 15:21 oui

Solution :

CHANGED GGUSER primary Group to oracle which is the primary group for oracle user. In my case oraInventory was under oracle group.