I am looking to service my Impreza shortly and was looking through the owners manuals for the specific grades of oil, etc.
However I am still unsure of what to buy.
Engine oil:
Apparently Subaru recommend sw30 with the codes SL, SJ or SH on it. I haven't a clue what these letters mean. Anyone any ideas ? As far as I was concerned, the only thing you had to worry about synthetic and semi-synthetic oils as well as the viscosity. In addition to this; I have heard that 'Millers' oils are good for this type of engine. What is so special about it ? Or what other oils would you recommend ?
Brake Fluid:
It says DOT 3 and 4 are both suitable. Is there any difference or advantage using one over the other. I know about the dry and wet boiling points, but can't seen any benefit of using DOT (I have always used DOT 4 in all my other cars before).
Diff Oil:
Again, any suggestions ?
Thanks in advance.
P.S. The car is a 2002 WRX UK Spec.