I ported twrp from oppo f1f.
We have been bootloader locked (just its not present fastboot). Now i found a way to install custom recovery to our device.
Step 1. Root with kingroot or kingo root.
Step 2. Oppo tool v1.6.5 https://drive.google.com/file/d/0B7J...w?usp=drivesdk
Download nd install nd open.
Nd then go to bootunlocker .Then press unlock nd tempered.see in attach.
Step3. Download rashr flash tool or flashify from playstore.
Backup your stock recovery.
Step 4. Download twrp 22.214.171.124 from https://drive.google.com/file/d/0B7J...w?usp=drivesdk
Step 5. Flash it nd reboot to recovery.
hey pleasee mans, Press thanks button for my hard work.
Good Luck. Tested by me.