Peter Horlock

Sorry to ask this question.
I ahve hada tek 3 remap on my My01wrx, i was told by BRD to put in a castrol RS oil type, any idea's on the grades would be helpful
Yours
Peter

richiewong

10/60
http://bbs.scoobynet.co.uk/showthread.php?t=378713

oilman

iTrader: (9)

Hopefully not 10w-60 as it's too thick.

The car requires 5w-40 or 10w-40 preferably fully synthetic.

I would suggest Motul or Silkolene.

Cheers
Simon

APIDavid

iTrader: (4)

We disagree Oilman, 5W40 is too thin and you'll break it. Minimum 10W40 in a Subaru Turbo.

I see the results of thin oil in Subaru's every day. Theorise till you fall asleep;

5W40 is TOO THIN.

David API Engines / APi Impreza

oilman

iTrader: (9)

We'll agree to disagree then.

Cheers
Simon

Jake

RS 10/60 as reccomended by Bob R.

Andrew Timmins

APIDavid,

How is a 5W-40 too thin and a 10W-40 okay?

Once the engine is up to temperature the viscosity would be about the same for both. If it was much thinner then it would be classified as a 5W-30.

How can improved oil flow at lower temperature be considered a disadvantage? Once warmed up to 100C a 0W-40, 5W-40 or 10W-40 would all fall into the same viscosity band of 12.5 to <16.3

The table here shows the viscosity ratings for different weights of oil http://www.infineum.com/information/viscosity.html

I'm not looking to cause an argument, I'm just interested in the reasoning behind your point of view.

Andrew

oilman

iTrader: (9)

I posted this elsewhere following a request for specific recommendations, it should be of no surprise as it's probably in your handbooks anyway.

Well, I've go recommendations from three seperate companies who are all experts in oil.

1. Silkolene Technical Department
2. Motul Technical Department
3. OATS - The largest proprietory oil recommendation database in the UK.

And, these were the recommendations that I recieved from them:

Firstly, lets get straight the viscosities available to you (as most work on matching a viscosity to an ambient temperature similar to the way handbooks list them) and the temps they are designed to operate at.

-20°C and above, 10W-40 or 10w-50
-15°C and above, 15W-40 or 15w-50
-25°C and above, 5w-30 or 5w-40

Impreza 2.0i Sport 1996-00

Motul 5w-40 or 10w-40
Silkolene 5w-40 or 10w-40
OATS 10w-40

Impreza 2.5i 4WD 2001 onwards

Motul 5w-30 or 5w-40
Silkolene 5w-40
OATS 5w-30 or 5w-40

Impreza 2.0i WRX/STi Turbo 2001 onwards

Motul 5w-30 or 5w-40
Silkolene 5w-40
OATS 5w-30 or 5w-40

Impreza 2.0i Turbo 1994-00

Motul 5w-40 or 10w-40
Silkolene 5w-40
OATS 10w-40

Impreza 2.0 4WD 2000 onwards

Motul 0w-30, 0w-40, 5w-30 or 5w-40
Silkolene 5w-30 or 5w-40
OATS 5w-30 or 5w-40

Impreza 1.6i, 1.8i 4WD 1993-96

Motul 5w-40 or 10w-40
Silkolene 10w-40
OATS 10w-40

They all specify that "fully synthetic" is recommended.

What's interesting about this is that they all tend to agree on grades pretty much and that unless the there is a non stock requirement like track days or modifications increasing BHP that 5w or 10w is favorites and that SAE 30 or 40 is the preferred range. 15w may be to heavy and sae 50 can be used if you are running high temperatures.

I further asked Motul concerning the oils used by the Subaru World Rally Team and they listed the following as being used in the cars.

Engine: Motul 300V 5w-40 Fully Synthetic
Gearbox: Motul 300 75w-90 Fully Synthetic
Brakes: Motul RBF 600 Brake Fluid

Hope this helps,

Cheers
Simon

APIDavid

iTrader: (4)

You won't get an argument from me. Oilman has replied more than eloquently about this. My point is, that, in our experience driven enthusiastically on the road we have a number - far too many, of cars arriving to us with 0W & 5W oil in them that have suffered crank failures.

We seem to be generally agreed that 10W something is Ok - why risk using a lower viscosity that has been known to cause trouble.

All the oils are on the same shelf at the store - not hard to pick 10W - why not??

David APi Engines / APi Impreza

Vegescoob

That's it my head has just imploded!!!!
Oil I hate the stuff!!!!!!

APIDavid

iTrader: (4)

See !! you're probably using the wrong oil !!!

David APi Engines / APi lmpreza

Andrew Timmins

David,

Do you think that you see engine failures with 0W and 5W oils just because they are more easily available to buy on the "High Street"? It is rare to find a fully synthetic 10W oil ouside of more specialised retailers.

Do you have more rebuilds on engines which run on semi-synthetic oil than ones which have been run with fully synthetic?

Andrew

Vegescoob

Lol. Touche.

Bob Rawle

Well I'm in process of doing back to back testing (AGAIN!!!) using castrol RS10-60 compared with Motul M300v 15:50 and again I will reiterate that the castrol seems to hold up just that bit better under stress (talking pressure response here), Oilman how have you formulated the view that the Motul 15:50 is "ok" but not the Castrol, or haven't you ? Considering we have a 10 v 15, which is better for cold starts and fits the Subaru scheme leaving a 60 instead of a 50 (or 40) which allows it to hold up better under higher temps, strange.

bob

LEN CARLYON

Well Peter, there goes another can of worms.
What oil ya gonna choose now then? ? ?

Personally I think that the 0 or 5W is too thin, (from an engineers point of view), these low viscosity oils are normally used where the ambient temp stays around 0'c, a minimum of 10W as Subaru UK recommend semi synth.
Some engines are designed to run on thinner grade oils, Cossies, Evo's etc. But with our countries moderate ambient temps in winter, in this engine knowing the problems they can have with hotspots internally I'd opt for the 10W40 min..semi or fully synthetic.
Mind you back in the days of the Mini's etc when we used 20w/50, now theres an oil......

micared

Yet to see anyone complaining of the effects of 10/60 in their car. Not inclined to change my opinion on this stuff, given that the only time there is a complaint about oil on here is when it appears to be about a problem caused by an oil being too thin. Accept the opinion that 10/60 gives greater pressure simply because it's thicker, nevertheless, better that than too little.

stockcar

our experience of engine failures tends to mirror "APIDAVID".....................run 'by the book' tends to be the most common engine to fail, most of our customers running even mildly modded cars run on 15w50/10w60 and in very general, terms none have issues................................

pays yer money and all that.................personally i'll continue to recomend & supply the "wrong" oils!!

alyn - asperformance.com

p.s. the SWRT have a very small mileage over which the engines are used before a complete rebuild (normally around 1000kms!!) and power is far more important then life in this application.................

Jiggerypokery

http://bbs.scoobynet.co.uk/showthread.php?t=316629

APIDavid

iTrader: (4)

Andrew, Bear in mind that a number of cars are serviced at garages, it is there that the 0W or 5W is fitted a number of times. We see a number of cars where it has just been serviced and gone a VERY short distance after the oil change . When questioned, the garage usually confirms fully synthetic 5W40 or 0W40.

However, there is the , possibly apocryphal, story of the failed Subaru specialist who was fitting Tesco oil, grade unknown, and charging for Fully synthetic super expensivo oil. Not heard of too many failures assuming that the story bears truth.

Where does that leave us??

We have one case this year of a performance car specialist, using a flush oil, then fitting 0W or 5W and not getting 500 yards............

AND no! I will not name either of the above mentioned businesses.

David APi Engines / APi Impreza

oilman

iTrader: (9)

This argument was done to death last time and went nowhere which I suspect is what will happen again. You pay your money and take your choice!

My personal and professional view (popular or not) is that the manufacturer recommends oil viscosities after extensive testing and these should be followed unless there are circumstances that warrant ignoring them. The only ones I can think of immediately are large increases in BHP and severe use of the car.

These extremes can also be overcomed by the use of better quality oils with higher film strengths and thermal stability as opposed to higher viscosity.

As I have said before, it's not my car or money involved here so I'm merely stating factual information which is not based on my experience of tuning or modding scoobies and I have respect for those who have this experience and knowledge.

Oil - what an emotive subject!

Cheers
Simon

The_Judge

Were these instances due to the oil, or the method undertaken to changing it? We know that most Subaru dealers change the oil as if it's for a Ford Fiesta, and I'm pretty sure an independent garage would do the same. Only the Subaru specialists seem to due it the safer way...

ALi-B

iTrader: (1)

Just spectulating But when asked what oil is used by garages in cars with dead engines - could it be that almost all full synthetic oils off the shelf at most garages and motor factors are in fact usually 5w-30, 0w-30, 5w-40 and 0w-40? As that is now the tendeancy for most modern car requirements and specifications (BMW's, mercs, VAG, Even Toyota specify 5w-20 in some applications ) and so is what most garages stock (well ours at least anyway).

Obtaining a fully synthetic oil with a cold viscosity rating of 10w or 15w with a 40 weight hot rating is almost impossible, the only oils I know of are semi-synthetics. (most of which are 10w-40).

So could it be you see less failures with 10w-40 full synthetic oils because the stuff doesn't exist?

Bear in mind engines still let go on semi synth 10w-40 - So I'd say the suggestion of going for 10w40 as opposed to a 5w-40 makes very little difference when comparing the hot temerature viscosities...both oils hot viscosity are almost the same. Saying a 0w or 5w is too thin at hot temperature when compared to a 10w all of 40 weight hot rating is like saying tap water is thinner than bottled water

So, IMO engines used enthusiatically wearing out and failing using either semi synthetic on 10w40 or fully sythetics of 0w-40 and 5w40 is not because of its cold viscoisty rating. Relying on the cold (w bit) rating in selcting oil is a very backwards approach imo.

I'd much prefer to stick with the lowest cold rating I can find, and for enthustiastic use selecting a thicker grade hot viscosity. That being 10w-50 or 5w-50 (5w-50 does exist - even if it's like hens teeth to find in the UK).

Now I could mention oil manufacturers use of viscosity improvers to make it thicker when hot and also still use mineral base oil on their branded "fully" synthetics (Mobil, castrol etc). How these cope under hard use, shear and high temperatures dictates far more the suitability of the oil than it's branded viscosity on the bottle. As what was initially poured in can be completely different just after a few fast laps of a race track or 3 months on the road. But that's another long winded debate!

.

oilman

iTrader: (9)

You're quite right.

As I've pointed out before, inferior petroleum oils need VI Improvers to work as multigrades and the wider the viscosity range the more they need which in turn makes them more prone to shearing (thinning with use).

The less of these additives the better the oil stability and synthetic oils need much less and in some cases none at all as the basestocks are already thermally stable. The main point here (and as stated before on various threads) is that a proper synthetic 5w-40 or 10w-40 is a better all round proposition than a hydrocracked/mineral/petroleum sae 50 or 60 after 1000 miles of use as the viscosity is retained for a much longer period.

I find it hard to believe that a 5w or 10w cold crank viscosity has that much effect in a modern turbocharged engine so long as there is no metal to metal contact which cannot be the case with esters as they are surface-active and therefore stick to the metal surfaces electrostatically.

Here is some reading on VI Improvers:

VISCOSITY INDEX IMPROVERS



As a lubricant basestock is subjected to increasing temperatures it tends to lose its viscosity. In other words, it thins out. This leads to decreased engine protection and a higher likelihood of metal to metal contact. Therefore, if this viscosity loss can be minimized, the probability of unnecessary engine wear will be reduced.



This is where viscosity index (VI) improvers come in.



VI improvers are polymers that expand and contract with changes in temperature. At low temperatures they are very compact and affect the viscosity of a lubricant very little. But, at high temperatures these polymers "expand" into much larger long-chain polymers which significantly increase the viscosity of their host lubricant.



So, as the basestock loses viscosity with increases in temperature, VI improvers “fight back” against the viscosity drop by increasing their size. The higher the molecular weight of the polymers used, the better the power of "thickening" within the lubricant. Unfortunately, an increase in molecular weight also leads to an inherent instability of the polymers themselves. They become much more prone to shearing within an engine.



As these polymers are sheared back to lower molecular weight molecules, their effectiveness as a VI improver decreases. Unfortunately, because petroleum basestocks are so prone to viscosity loss at high temperatures, high molecular weight polymers must be used. Since these polymers are more prone to shearing than lower molecular weight polymers, petroleum oils tend to shear back very quickly. In other words, they lose their ability to maintain their viscosity at high temperatures.



Synthetic basestocks, on the other hand, are much less prone to viscosity loss at high temperatures. Therefore, lower molecular weight polymers may be used as VI improvers.



These polymers are less prone to shearing, so they are effective for a much longer period of time than the VI improvers used in petroleum oils. In other words, synthetic oils do not quickly lose their ability to maintain viscosity at high temperatures as petroleum oils do.



In fact, some synthetic basestocks are so stable at high temperatures they need NO VI improvers at all. Obviously, these basestocks will maintain their high temperature viscosities for a very long time since there are no VI improvers to break down.



Cheers
Simon

micared

At the risk of perpetuating another long-winded debate which, as oilman says, will probably end up going nowhere, we've heard from the people who've seen and repaired the results of using oil that is under suspicion of being too thin....is there anyone out there that suspects they've had to rebuild an impreza because of the use of 10/60, and if so, what were the circumstances. Forgive my pursuit of this, however I have a vested interest, as that's what currently resides in the sump of mine! I don't want to dismiss an oil that I have no issues with until someone shows me the results of a problem caused by it. If no-one can provide any actual reason other than theory to be disparaging about it, perhaps the theory is incorrect?

sooby

Just out of interest. I have had several communications with IM and they steered clear of recommending fully synthetic oil even when specifically questioned. This was about 18 months ago.

maci

iTrader: (3)

I quite agree with Oilman and Ali-B.
In my last 3 cars I always tried to put very good quality oil and regarding the temperature. Since I make lots of trips to central europe, and belive me at this period of the year, it can easily be -15 degrees over there, my Sooby has a 0w40 in it. In the spring I might go for 5w40, but for now this just ok. If you go up north, let's say Finland, there everybody uses 0w40 or max 5w40.
I think the only risk here is that the oil might loose its viscous properties and then is no good any more, but if you check the oil often you can see that; or sometimes even feel it. In my last car, after about 6000 km I felt that acceleration was not smooth any more for ex.

crusher

10w 50...good compromise...

oilman

iTrader: (9)

Agree, that's why Silkolene recommend it for modded or track cars.

Cheers
Simon

Andrew Timmins

Bob,

Have you measured any difference in oil temperature when using these two oils? The reason I ask is I read a post recently on this forum http://theoildrop.server101.com/cgi/ultimatebb.cgi where someone switched a VW 1.8 turbo engine from Mobil 1 15W-50 to 0W-40. They reported a decrease in oil temperature of 20C. Does your testing suggest lower oil temperatures when using a thinner grade of oil?

JIM THEO

...yes but you already mentioned how bad are viscosity improvers for an oil thus Motuls and other ester based oils remain stable under extreme conditions, or have I miss something?
JIM