looking at the castrol site ive seen this edge oil which everyone talks about on here, i used to use 0-40 in my typeR engines and the car responded very well. is it too thin for the wrx engines? would 10-60 be a better option?

 

its the viscosity temperature rating of the oils

In this cold weather, it is beneficial to use an oil that has good cold start flow properties as it will get to the parts of the engine that need it far more quickly.

The "w" number which means winter is the key here and the lower the better.

It may seem odd but a 15w or 20w will struggle to get around the engine in very cold temps and I would strongly recommend a 10w or better still a 5w for better cold start performance.

90% of all engine wear occurs on cold start because the oil get thicker the colder it is which causes engine wear.

These numbers explain what I mean and bear in mind that the oil will be the following thickness at 100degC (sae 40 = 14cst, sae 50 = 18cst and sae 60 = 24cst)

At 0degC these are the numbers (thick!)

Grade.................At 0C.........At 10C...........At 100C

0W/20.............328.6cSt......180.8cSt..........9cS t

5W/40.............811.4cSt......421.4cSt..........14c St

10W/50............1039cSt.......538.9cSt..........18cS t

15W/50.............1376cSt.......674.7cSt.........18cS t

20W/50.............2305cSt.......1015cSt..........18cS t

If you are using anything more than a 10w oil, always warm the car properly before driving it as the oil needs time to circulate.

Just a word of warning really.

hope that answers your question:P

 

cheers for that!!! so you dont think a 0-40 would be too thin then for these engines?

 

For a road-going Impreza it isn't reccomended.

 

id go for 5-40 myself

 

woolz m8

go here

http://www.opieoils.co.uk

they got a section that advises wot oils u can use proper company also