The Nissan Almera 1.5 S, N16 petrol is a well designed strong motor together with a strong trouble free manual gearbox. I have worked as a trained mechanic for 25 years in a main Nissan dealership. Many people don't realise that you need to change the gear box oil every 50 - 70,ooo miles. The N16 Almera has a oil filler plug on the front face of the gearbox which becomes seized from metallic corrosion over time and needs to be opened every 2-3 years, (smear copper grease on the thread when you get it off) other wise the 10mm plug will become seized for life. We have many cars in where it's seized beyond repair, due to lack of maintenance. A tip we use in the workshop is to heat the g/bx casing carerfully with a hot air gun, to expand the thread, to assist it's undoing) be careful however to heat everything gently. Remember to Torque the plugs to the correct settings as these are vital seals: 35nm Filler plug, / 29nm Drain plug.

The gearbox oil is relatively cheap to purchase. You will need 2.3ltr. about £30. Nissan don't specifiy a service interval for this oil, though Toyoto recommend changing the oil at 70k. The Nissan gear box oil needs changing as the viscosity is worn down over miles of driving and will eventually wear out the gearbox bearings. This leads to failure of the gearbox. If the oil is changed every 50 - 70k the manuakl gear box will be smooth with syncro gear changing and will last 200 k or more.