There are two options for you man.
1: keep it as it is and take a 20w-50 Mineral oil (dont use 5w-x or 10w-x) only 20w-50, keep it till the car start giving smoke continuously so at that point you will open the engine at once and replace its valve seals and rings etc, so you will do a KHARCHA at once. the amount of oil decreasing will be reduce by using 20W-50 better you use ZIC as its API is SM.
2: change the valve seals which will cost you something like that.
Rs. 400 for valve seals, Rs. 400 for Head gasket and Rs, 1000 for the mechanic. (it is rough estimate dont take it final). so after this your car will not smoke your engine will not reduce oil, and the engine and tail pipe will remain clean and you will be able to use 10W-X OILS.
When 6 month ago i faced the same problem i used the 2nd option.