Can i use 0/40 oil in 2001 wrx. Fully synthetic. Halfords got loads of deals.:-)

 

No, 10-40 would be my choice

 

A 0 weight isnt ideal. 5 or 10/40 would be my choice

 

Don't use 0 grade oil in a scoob mate.

 

the 0w part of the oil is cold weight so surely 0 is ok as you need thin oil at start up.
the 40 part is when its warm so surely its ok.

i dont use this weight but cant see why it would cause problems, maybe someone who knows oil can explain.

 

Don't know the reasons behind it but ive been told its not a good idea. Mabe due to the heat of a turbo engine? I always used a 5w 40 but my engine builder told me to use at least a 10w 50. I think the 2.5 engine requires a heavier grade than the 2.0 for some reason, heat i expect.

 

but the 0 is cold viscosity, the 40 is when its hot.
i understand the 40 or 50 part as you need it when the engine is hot but surely its better to have a thin oil on start up ??

come on somebody must know....

 

I understand and coukd be wrong that the wider the temp range. I.E. 0/40 is a wider ranger than 10/40 then the less stable the oil is at the higher temp. There must be a difference other wise why bother making 5/40 or 10/40. Because 0/40 would cover everything inbetween. Im led to believe a 0 weight shouldnt be used i a subaru. I use 10/50 in mine

 

lol i have no idea i use 5w 40 as the car has always been run on this.


just interested to know about the 0 weight oil

 

This is from Opie oils website.

Maybe the highlighted part is the reason for not using a 0 rate in a scoob.

 

the part you have highlighted is about the warm rating which is 40 on the oil the thread is about

if you go by the advice in the quote 0w40 sounds good as it will flow freely when cold and has a 40 rating when warm.


im confussed to be honest as like you say tuners etc never recommend 0w40 oil.

 

Maybe the 0 rate will flow freely when cold but its so thin it brakes down when hot. Or maybe its down to the size of oil holes in our engines. Dont know but its an interesting subject. I always used a 5w 40 for the cold start reasons to mention but when paul built my new engine he told me never to use a 5w in a 2.5 and to use at least a 10w50. No idea why to be honest but i do as im told

 

lol im the same i just use what was recommended to me.

the 40 rating is how thick it is when hot though so its no different when warm to a 10w40 surely??

**** it im gonna google it i want to know now!

 

This is quite interesting, especially the cold cranking temp of the different grades.

http://www.kewengineering.co.uk/Auto..._explained.htm

 

Interesting. Also the load the oil will take on bearings which i why id guess a 0 weight isnt suitable

 

Right from what i gather reading that. The 0w is the base oil. using V1 improver's (polymers) that exp[and when heated gives the 30 0r 40. The trouble is the V1 improver's are not shear resistant. So a 0w 40 uses more improver's making the oil less shear resistant. That must be the issue with a 0w in our engines.
Although it goes on to say that modern V1 improvers are more shear resistant than the mineral base oils. So still doesn't really explain why tuners say stay clear of 0w lol.

 

lol im still none the wiser.

 

Well i can help chopper out.

The reason to use 10/50 in a 2.5L is they generally run circa 10 degrees hotter than a 2.0L.

As for the zero rated oils, i'd say it's fine in winter but not so in summer, i'd also suggest as above the key is in 90% of engine wear being caused in the first 5 mins after start up.

 

I had an idea i was told to use a 50 rather than 40 was due to heat but cant understand why a 10w instead of a 5w as that has no effect once warmed up.

 

This may help to explain oil viscosity, but maybe not for Subarus.

http://www.kewengineering.co.uk/Auto..._explained.htm

Use Millers CFS 5/40 in the winter and 10/40 in the summer, would not use Halfords own brands.

 

^^ that's just cut and paste from the ling i posted. Still doesn't explain why Tuners and engine builders advice us to stay clear of 0w oils in our cars.

 

Have a read of this one as well.

https://www.scoobynet.com/general-te...-10w-60-a.html

 

Well i bought mobil1 0/40 but after reading i may take it back. Halfords have 30 per cent off but couldnt find a 10/40 fully synthetic.but i think there was10/50 etc.:-).hmmm.decisions.

 

Interesting thread that Inviorman

I have come to the conclusion the controversy is with 0w and 60 weight oils with most agreeing anything from 5w 40 to 10w 50 is fine for the uk. The 10w 50 probably being better suited for hard drivers and the hotter 2.5 engine. Which to be honest is what i've always thought . Racers or very highly yuned engines may go to 15w 50 or 20w 60 but not for every day use.

I was interesting to read claims of engines going bang due to 0w oils but no evidence to back up what happened or the exact cause.

I would suggest to the op to steer clear of 0w and go for a quality oil in the 5w 40 to 10w 50 range.

 

Ok, i will take back and change for 10/50 or similar, but it seems strange that halfords stock loads of oils in lots of variations but i couldnt get a name brand 10/40 fully synth, part synth yes. Full synth were either 5/30,0/40 and a few random 10/50,15/60.all good brands mobil1;castrol,etc. Didnt look at halfords and the one i went for was 50quid without discount. If these forums werent around i would have probably gone for 10/40 part synth and thought nothing of it. :-)

 

Even opie oils recomend 5/30 which on here is a no no.

 

Maybe the 5w 40 fully synth would be the best all rounder for yours. I use Fuch Titan race pro s. Mobil 1 or shell helix are also good oils that wont break the bank too much. I wouldn't bother with Halfords branded personally. Best to stick to name brands when it comes to oil imo.

The Opie site also recommends a 5w 30 for my RB320 which is way to thin imo. I use a 10w 50, a 5w 40 minimum

 

I am currently running Millers CFS 5/40 with no problems and about £60 for 5 litres.

 

I have just put the 5/30 Mobil 3000 fully synthetic in my hawkeye 2.5 as that is what manual stated and the recommendation of the book in halfords. Hope it's ok. Although I Will only have it in for about 3000 miles before I change it, then Will be using the 10/40

 

I didnt buy or look at halfords oils they have a sale on mobil and castrol etc. Might go mobil 10/50 i think. Stange how its the 5 to the 0 that causes the aggro! :-)