Choosing the correct oil is vital for your engine to perform and last . Using the correct oil makes your engine run more smoothly and extends your engine life . So it makes sense to choose the correct oil , brand is a big factor as well . In your service book you will see this chart which explains the correct oil to use for your engine . Its easy to follow if you keep it simple . Unigrade oil in the top section of the chart is a specific oil , made for your engine , Mutigrade oils are based on where you live . For example , if you live in outback australia , desert temps can get freezing to extreme during the day . So you would need a 10W-40 . if its a diesel a 15W-40 . The range (15W-40 ) is the viscosity of the oil . Viscosity means the flow rate of oil . When oil gets hot it flows quicker , when cold , it thickens so when your car sits overnight in a cold climate in a 15W-40 situation , the oil will not give sufficant lubrication untill a 15c has reached and will give maximum flow at 40c . The quality of oil then comes into the scene , do not mix oils , its a good idea that when you get a service to get 500ml off your mechanic for top ups , then you know that you have the correct oil . If your engine is rattling from that $99 service you got for a bargin , these are a good sign that your engine dont like it , it will cause more friction , higher fuel cost's more expensive future repairs , even engine seizure . Im not saying put a high grade full synthetic oil in at $70.00 a bottle , im saying if you got a service for $99.00 i guarantee the quality of the oil they used will be cheap ( and nasty ) , not to mention the filter which would be ( dirt ) cheap . the service is probably done more harm than good , you wont see the damage straight away , but in time , for sure you will .

Manufactors put this chart in your service book for a reason , say if you lived in sydney , in winter its freezing so you will need a thin oil 10W-40 . Cairns is completly diffrent it will need a 15W-40 . It depends on what type of engine you have as well , like if you have a high performance engine with big oil galleries and you lived in cairns , it would be vital that your engine gets immeadiate lubication so a thicker oil with high temp is needed  , if a high performance modern car in cairns with small oil galleries you would choose a full synthetic oil as they have high oil pressure . Always use the recomended oil for your engine with in your range . I use Penrite oils and Nulon oils , Penrite is top of the range and is classed as a high quality oil , so is Nulon , they both have Full and Semi synthetic oils . Semi synthetic oils work well in most modern and post 10 year vehicles in Cairns , most engine wear is caused at start up . When you change your oil first look at the color of the old oil . In this case if its brown or black with gritty feel to it  , run some engine flush through the old oil for 15 to 20 mins , get the engine hot , drain the oil overnight with the filter removed , ensure its in a dust free area . add the fresh oil and filter in the morning , i promise you you will feel the diffrence and you car would last a lot longer . My Services start from $130.00 using Quality oil and Filters and i wont give you a repair list as long as your arm , its one of the oldest tricks in the book when you get your car serviced , they advertise a dirt cheap service to get your car in to find faults and you end up wit a list of repairs that ( they say ) you ( need ). Choosing the right Mechanic should be the same as choosig the right oil .