Right chaps im going to do a oil and filter change on my 09sti very simple to do

The only problem i have is that ive been looking into what oil now after a google ive found its 5-40 fully synthetic

Now ive just looked on halfords and it says its 5-30

How can 2 differant oils be recommended for same car

 

go buy what engine builders recommend on the 2.5's - 10w50!

 

I use 5w-40 Gulf with black filter in my hawk and have done for the last 3 years

 

Now thats 3 differant ones the manual says 5-30 fully sythetic

 

Iv only ever used Fuchs 15-50 in my forged 2.5s

 

tdr racing recommended fuchs 15w 50 as i too was in the same boat getting confused on oil choice, he said i would be topping up with the 5w 30/40 as it'll use it

 

Do what the manual says, written by Subaru. Or wait for the really clever people to tell you.

 

i would go for a thicker oil than a 5 , i would do at least a 10/40 , 5 is for fuel economy not engine life , and forged as above 15/50 or similar

 

Been using 10/50 for 12 yrs in my Wr1 with no probs !! 😀

 

The lower the numbers, the thinner the oil. So 5/30/40 will have less drag and give better economy. This is why Subaru state this but it's based on brand new engines. As the engines wear, it takes longer for the rings etc to seal, so you'll burn a little oil at start up. Which is why people recommend a thicker 10 weight oil. If forged, it takes longer still for pistons etc to heat up and expand/seal. So 15 is recommended. If unsure, use 5w/40 first and monitor how much oil you are using. If none to very little, stick with it. If you are using a noticeable amount between changes, try 10w40 next time.

 

the oil argument the thicker heavier oil provides more engine protection when things get warm as they easily do , oils break down as they got hot or too hot and they don't do there job as well , so my engine builder for a forged lump has said 15/50 motul 300v competition or the Fuchs version which is cheaper but still good , for a standard engine as in not forged i would still use at least a 10/40 or higher , my above comment about 5 being for fuel economy it's a thin oil to let every thing run with less resistance but a thicker oil will give more protection , in an ideal world starting a car on a 5/ ? oil then when it's warm change it to a 10 or 15/? oil so it gets its best protection on start up and then best protection with a thicker oil when it's warm , as that will never happen , start the car up to 30 seconds idle just to let pressure build and then drive it like an egg is on the accelerator, coolant warms up , people think car is warm it's not , double coolant warning up time before oil is warm