Halfords are doing their usual bank holiday offer of 20% off Castrol Magnatec oil

The 10W-40 version that is appropriate for the Impreza Turbo
is now called Magnatec for Modern Engines (used to be called "for Advanced Engines")
Now £17.xx rather than £21.xx

Stock up now (I have)

 

I wouldnt put it near my engine, even if it was free.

 

Why not? Its bloody good stuff. Subaru dont actually reccomend a fully synth oil.

"Customer Technical tell me that as the actual API/ACEA specification of the oil requested by Subaru is fairly standard and they do not actually specify full synthetic then a cheaper ( but excellent performance alternative) would be 10w 40 Castrol Magnatec. If you use your car really hard ( ie do things like track race days) then I would stick to full synthetic otherwise Magnatec would be fine. "

Info from an indipendant expert I have been in touch with. PS, I work in the oil industry.

MB

 

Thats just my choice, it is a performance engine, and I would not feel confident with a semi synthetic oil. More so, with it being turbocharged, as oil temps will be that little bit higher.
Each to their own.

 

Seriously its not good enough for the Impreza, oil film will start to break down due to carburisation of the oil ... turbo does that.

Bob

 

I know everybody has there own choice and I used to put Mobil! in everything but whats get me is how why does an authorised Subaru dealer as one close to me sell it ,put it in on your £400 service and all with the backing of Subaru and their warrentys if its s***.
Its not as if its £4.99 crap from your local spares corner shop.
Gene

 

Bob - at what temperature does the oil film start to crack and coke?

MB

 

Great deal,been using magnatec in my scooby and its much cheaper than my subaru dealer charge for it.

 

No particular temp, its not like turning a switch, elevated temperatures in the turbo cause oils to degrade progressively depending on the composition, few of the Magnatec type oils are good enough for tuned turbo engines, viscocity index is not good either, carburisation due to consistent high temps (for the oil) will degrade it. If you can find it read Big End No 3 thread for more detailed info.

 

There must be some reason Subaru, Prodrive and many rally teams use Motul - I wonder what it is....

Trout

 

Is there any reason why I should not go from semi to fully synthetic oil in my car?

It has done 100k on semi synthetic..

I cannot see a reason but almost feel that I should stick with what the engine is happy on, either that or I have been bl00dy lucky! :lucky:

JGM