oilman

iTrader: (9)

Well, I've done a lot of homework in the last week and I've got recommendations from three separate companies who are all experts.
The last oil thread I started caused much debate and I guess that this one will go the same way - Still, that's what Forums are for!

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

[Edit: please contact webmaster@scoobynet.co.uk for details of advertising opportunities on ScoobyNet]

Cheers
Simon

john banks

What do you suggest for Subaru engines running c.200 BHP/litre?

oilman

iTrader: (9)

If you are not running "excess" temperatures then use the recommendations above but use a "proper" fully synthetic which will be more thermally stable and good for up to around 130 degC.

If you are running higher temps and need more top end protection then use a 10w-50 or even 15w-50 (you will sacrifice some cold start protection here as the oil will not circulate as instantly as with a 5w or 10w). Again make sure it's a good one as you will be defeating the object of the exercise if it isn't.

That would be my advice.

Cheers
Simon

john banks

Motul 300V 15W50 in at present. Would I lose anything in shear strength by going to 10W40?

NelsonUK

Thanks for the info. mate

oilman

iTrader: (9)

The 300V products are very shear stable and I would say 10w-40 would be absolutely fine. You will also get better cold start protection as the thinner oil will circulate more quickly.

Cheers
Simon

lchris21

"Impreza 2.0i Turbo 1994-00

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

Are above recommendations same for WRX 93 JDM ?????????

Cheers

stockcar

the one thing you haven't mentioned in your very informative piece is that teams like SWRT fully rebuild their engines at a max of 1000km!! for that sort of timescale and stress you could probs run halfrauds cheapo and still get some where near....................say what you like about 15w50, 10w60, etc. but a lot of peeps involved in this forum (including ourselves and the teams we have supported) have used various grades over the years but found that certain oils give far better protection/wear rates for their use.....................

just a different angle.......................

alyn - asperformance.com

p.s. who needs a group buy to genuinely offer the community a "deal"................

DreXeL

I personally run Mobil 1 Motorsport 15w50 on my 110k mile 340bhp Scoob, and change it every 3k miles.

TONY F

hi alyn a lot of peeps on here say not to use 5v40 too thin
whats your veiw, i,ve had no probs so far


tony

Gear Head

iTrader: (2)

Same here, although my sti 4 has 294bhp (before decat atleast!)

JohnD

iTrader: (5)

I recently mailed Millers for info. on their road and competition ranges as I am currently using XFS 5/40 (full syn. road) and am contimplating CFS 10/40 (Full syn.competition) at the next oil change in my 03 STi PPP but was unsure of it's suitability as an everyday road oil. Although they did not provide a definitive answer to my initial query their data sheets stated that their 10/40, 10/60, and 15/60 competition oils are "Formulated with 100% synthetic base fluids, including a synergistic blend of 3 esters, combined with the latest additive technology for maximum performance"
If someone out there can vouch for there suitabiliy as a road oil then maybe Millers CFS range can be added to the list of "proper" synthetics?
Having said that, I doubt if the XFS is based on the same technology (probably hydrocracked?) but I swear my engine is a tiny bit quieter on XFS 5/40 compared to the Castrol RS 10/60 I used before?
JohnD
PS Im sure asperformance may have something to say here as I know they recommend Millers?

Kevin Groat

I tried one of the Mobil 5w/40's and my STi3 sounded like a bag of spanners on startup from cold - fine when warm but quickly changed back to a 10w/40. Using the Silkolene Pro R (or is it S?....it's the red stuff) and seems to be happy enough on this.

washer

hmm run my sti on cheep min oil no prbs yet and it gets hammered cas import recons he seen more blown engines on sim so im happy

malinen

http://theoildrop.server101.com/ubb/...c;f=3;t=001993

Enough said...

TomRa

I bought 6 litres of Motul 15/50 300v for my 93 WRX Ra through the recent group buy, would 10/40 have been a better bet?
Thanks
Tom

oilman

iTrader: (9)

You can certainly use 15w-50 without problems but the oil companies seem to favour lower viscosities for the scoob.

I know from past debates that many tuners and "people in the know" disagree.

I've just posted the "technical" recommendations which are not based on hearsay or general consensus - they are technically correct.

Oil is a personal thing and debates will rage forever!

Cheers
Simon

WRX STI Type RA.

John...A friend did infact ..Ask a millers rep...To see if their oil is hydrocracked.....His reply was.....NONE OF MILLERS SYNTHETIC OILS ARE HYDROCRACKED..And was not suited by this thought at all.Hope this helps....Kev.

Vegescoob

I've always avoided using oils labelled as competition oils in road cars cos I was under the impression that they are low detergent and therefore meant for very frequent changing ie. after every competition event. Have I been wrong?

crusher

my local dealer recons that subaru have issued a buletin which tells them to use 15w 40 grade in all imprezas....anyone else heard of this?....

scoobyster

Thanks for putting up info for NA as well as turbo, we usually get left out of this debate!

I have 10W60 in my MY95 1.6GL and MY98 2.0GL at the moment, and have some more stored for doing the next change due in January. Am I correct in thinking 10W60 should give the same cold start protection as a 10W40 or 10Wanything-else? Is this true in practise as well as theory?

I suspect you can guess which brand I'm talking about from the rating; it seems to have gone out of favour on here recently due to not being a 'proper' synthetic. It has been fine for me for over a year, although presumably my NA engine will be giving it an easier time than a turbo. I'd rather have improved cold start protection as the cars do a fair number of sub 3 mile journeys, so will switch to a 5W next time I think.

JohnD

iTrader: (5)

Try an experiment (very scientific ) Get some translucent 35mm film canisters (eg Fuji) and put the same amount of oil in each, one with the 10/60, one with 10/40 and another with any other grade for comparison. Pop them in the freezer for a day then compare the viscosity of each OK, so it's not particularly scientifically based, but it was enough to put me off using 10/60 in the winter at least!
JohnD

TomRa

If anybody in North Scotland area would like to swap 6 litres of Motul 15/50 that i have for a 10/40 motul or silkolene can they let me know?
Thanks
Tom

PO54

Pretty much matches what AMSOIL told me for my MY04 WRX - use fully synth and 0w-30 series 2000

http://www.amsoil.com/products/tso.html

I'd been so put off using a 0w-30 from what I'd read here that I've gone with their 10w-40 high performance stuff.

I was under the impression that most synthetics are not really "synthetic" and that AMSOIL and Redline were two of the best???

Comments? Oilman - what do you think of the series 2000?

sulli

The Castrol RS 10w60 in my 100k 250+bhp classic, changed every 3k miles, seems about perfect.
No oil use between changes, fairly quiet on start-up, and engine is very smooth.
What does the 60 bit mean in the 10w60?

sooby

PO54,

From what I can remember AMSOIL does not conform to any of the specifications laid down by any of the governing bodies. I cannot remember what additive exceeds recommendations. Whether AMSOIL are correct or not (have a better engineered oil), not having the right certification for your oil could spell warranty trouble.

Just a thought.

Edited to add that I've been to their website and they claim to meet API Service Classifications required by many manufacturers. I'm pretty sure their site was where I read the reasons for them not having API certification before <shrug>!

PO54

Dunno whether AMSOIL comforms to the API standards but I know it's one of the few ester synthetics (like Redline) - having my handbook would help I'm sure but it's still on it's way from the Euro dealer it was ordered through I've just rang my 3 local dealers (helps to have a few in reasonable distance to compare) about my 1000 mile oil change and had quite different opinions (see new thread) but basically semi 5W-30, semi 10W40 and synth 0w-40 were the recommendations and all were happy for me to supply my own oil (didn't even ask what it was).

oilman

iTrader: (9)

I'm not sure that I'd use 0w something in a scoob. Besides in our climate whether the oil pours to -35 degC (0w) or -25 degC (10w) is somewhat irrelevant IMHO.

Follow the manufacturers guidelines as I posted would be the best advice.

Regarding Amsoil, it's one of those companies that merely says meets and/or exceeds all API specs. I Wouldn't say that it's no good as I do believe they market proper synthetics but I would still use an oil that has some form of specification other than the viscosity. This to me is just common sense.

It's a murky old world out there and I prefer oils that I know about and can obtain good technical info on.

Cheers
Simon

oilman

iTrader: (9)

Hope this helps:

What is this thing called viscosity?



It’s written on every can of oil and it’s the most important visible characteristic of an oil.


The viscosity of an oil tells you how it reacts in certain circumstances and how it performs as a lubricant.

When a oil is subjected to external forces, it resists flow due to internal molecular friction and viscosity is the measure of that internal friction. Viscosity is also commonly referred to as the measurement of the oils resistance to flow.


There are two methods of viewing an oils resistance to flow. Firstly there is Kinematic Viscosity which is expressed as units indicating the flow of volume over a period of time and this is measured in centistokes (cSt).

An oils viscosity can also be viewed by measured resistance. This is known as Apparent Viscosityand it is measured in centipoises (cP).



However in the real world an oils viscosity is also referred to in such terms as thin, light and low etc. This suggests that the oil flows or circulates more easily. Conversly, terms such as heavy and high etc suggest the fluid has a stronger resistance to flow.



The reason for viscosity being so important is because it is directly related to the oils load-carrying ability - The greater an oils viscosity, the greater the loads that it can withstand. (It must be added when new not over a period of time as all oils “shear down” with use)



An oil must be capable of separating the moving parts in your engine at the operating temperature. On the basis that an oils viscosity is related to its load carrying ability, you could be fooled into thinking that “thicker” oils are better at lubricating but, you’d be wrong in this assumption. The fact is that in the wrong application a high viscosity oil can be just as damaging as using a low viscosity oil.



The use of an oil that’s too “thin” can cause metal-to-metal contact, poor sealing and increased oil consumption and conversely, an oil that’s too “thick” can cause increased friction, reduced energy efficiency, higher operating temperatures, and poor cold starts in cold temperatures.



It is very important that you select the correct oil, not too “light” or too “heavy” and your Owners Handbook is a very good place to start as it lists the temperatures and options.



Oils thicken at low temperatures and thin as the temperature increases. The actual rate of change is indicated by their viscosity index (this number normally listed on the oils technical data sheet indicates the degree of change in viscosity of an oil within a temperature range, currently 40-100 degrees centigrade)



An oil with a high viscosity index, will normally behave similarly at these two temperatures but an oil with a low viscosity index will behave quite differently. It will become very fluid, thin and pour easily at high temperatures. A higher index is better!



Multi-grade oilsare designed to perform at high and low temperatures by adding polymers to a base oil (5w,10w, 15w etc) which are heat sensitive and “uncoil” to maintain the higher viscosity sae 30,40,50 etc. This means that the oil can be used “all year round” rather than using different oils for summer and winter.



It is important to understand that the selection of the correct oil for your car is not just guesswork, you must consider the temperatures at which you need the oil to operate a 0w, 5w oil is better for cold starts as the oil circulates more easily when it’s cold and is able to flow around the engine more easily and quickly, offering protection at the critical moments following cold engine start-up. These oils are also known to give better fuel economy and engine performance.



Finally, all oils “shear” or thin down with use and this means that an oil that started life as a 10w-40 will with use become a 10w-20. The period of time this takes depends on the type and quality of the oil. The most “shear stable” oils are proper Synthetics, either PAO (Poly Alph Olefins) or Esters which have very high thermal stability. They are in general of the more expensive variety but last longer and give the best levels of protection.


Cheers
Simon

Vegescoob

Oilman I'd hoped you'd answer my query ref competition oil in road cars.