Sweet ride, MA SHA ALLAH drive safe.
Firstly only use 5w-30 fully synthetic oil in R18 engine. no need to switch to higher viscosity. thats the maximum suggested viscosity for civic engine.
2ndly change your engine coolant o honda type 2. you will probably get pre mixed version so need to flush and fill in new orignal coolant.
also it would be best if you change the gear oil to orignal honda spec. since car is 80k driven so probably plugs, gear oil and brake discs change is due. however regarding plugs and disc u can decide after inspection.