Hi, ive an 02 sti about to have some light mods and remap(320 ish hopefully). No track days as yet so just fast road use.
Currently have millers cfs 10/60 engine oil in, would i be better off with 10/50?? cheers

 

I am using 10.50 in mine, but I think it's so close then it's down to preference.

The main differences that I have fould (research - not use) is that 10/50 is good for fast road use but you have to be careful when driving hard for long periods. 10/60 is better for lots of fast hard driving and track days but is a little thicker so will sap the odd few horsepower and you would "need" to uprate the oil pump (maybe best to do this anyway but I have standard one in my 2008 hatch).

I may be wrong on this thou so willing to stand corrected.

 

Better off using 10w40 fully synthetic unless heavily modified

 

10w- more "w" is for colder areas in winter.
in UK You could use 5w
and after "w" is oil thick- more =more thick
You could use even 5w30 motul but could leak if engine is "tired"
any ester oil from 5w to 15w and up to 50
millers fuchs silkolene pro s motul
main damage is when engine start-oil should keep "film" on it what easter oil does
next pressing/compression -oil should keep pressing/oil level should be the same dont deflect under pressing

 

millers 10w50 gone in today

 

The best would be a 5w40 or a 10w40, the latter number being (the viscosity) thick it is when warm, so the thicker the more drag, the more drag the more energy it uses, that energy comes from somewhere so you lose power because of that, plus it takes longer to warm up.
As said, a 40 is better than a 50 in your car

Tony