Oil Service of the Nissan Almera N16 should be carried out every 9k and a good quality semi or fully sythentic oil. Personally I use only a high grade fully synthetic oil such as Mobile One or a quality 5w30. There are many makes of oil on the market so check the API / SG rating on the container. Always changed the oil filter together with the sump oil. A tip for you: when you change the oil filter: prime the oil filter with a lick of oil inside the filter to moisten the filter before fitting. As the filter mounts at 90 degrees you can't prime / fill the filter, but the pre-lubrication will assist fast initial start-up. In the workshop we always change the sump washer: the torque is: 25 nm

Failure to change the oil will drastically shorten the life of this well built strong motor and lead to a degree of sludging which in modern close-tolerence designed engines is a bad thing. Get into the habit of checking the rear exhaust of your car to see how it's running: in a well maintained petrol engine it will be fairly clean with very little oil deposits: if the exhaust is very black with alot of oil, it perhaps shows signs of internal engine wear: such as the big end bearings or valve stem seals worn or oil control rings on the pistons. Check this with a trained mechanic or Nissan dealership.