You have been using earlier 5W20 (ZIC A+) and now you are facing with low compression issues.
Next, as you have told that you have shifted to 10W40 oil, which is again a bad selection of oil with regards to viscosity.
The correct oil for our climate here in Pakistan taking into consideration 1kr-fe engine is 5W30. Now since you have low compression issues, shift to 5W40. This is the max you can go in terms of thicker oil to give you some extra sealing.
Do not use 10W40 for 1kr-fe engine.
Also replace PCV valve as soon as possible.
NOTE: For most Japanese vehicles in Pakistan, 5W30 is the best oil viscosity for year round.