The Maruti Suzuki Ciaz has an engine oil capacity of 3.2 liters. You can follow the standard recommended schedule for most cars i.e. change the engine oil every 12 months or after every 10,000 km. According to me synthetic oils go well with the engine. I would recommend the Shell HX5 15W-40 and Shell Helix HX-7 Synthetic 5W-40 engine oils.