mattdoyle

Been offered 12 litres of Mobil1 0w/40w for £60

Is this suitable for my 55 plate wrx?

cheers

andy97

iTrader: (1)

If your car is standard and you dont hoon around all the time, then I dont see why not. I ran my standard turbo 2000 on mobil 0w/40 for 80k without any issues.

My car is highly modified now and I use Motul 15w-50

PetesDad

0W is very thin when cold ..... not sure I would recomend it. In fact, Subaru used to absolutely state that MOBIL 1 was NOT to be used in their engines!

£60 for 12 Litres isn't a great deal anyway I pay £36 for 12 Litres of Semi 10W/40, which is what you actually need.

andy97

iTrader: (1)

subaru saying that was a moth

I believe that subaru recommend 5w40 for their newage cars. There is bugger all difference in viscosity between 0w and 5w

harvey

iTrader: (48)

Unless your handbook states clearly that 0W40 oil is approved give it a wide berth. I would not use it in any of my Scoobs but my cars are 02, 00 and before so things MAY have changed.

PetesDad

Strange that they make the 2 options available then? 0W is frowned upon by Subaru, or certainly was 8 years ago when the Classics were being sold.

Shark Man

There is alot of stigmatism here on 0w and 5w oils, which I think has probably come over from North American, where alot of native car makers use 0w-30 and 5w-30 oils - even 10 years ago. Arguments enthrawl that its too thin, and on certain imports, it was. Then they mix it up and think 0w-40 is the same. You can thank NASIOC for that, as well as owners that can't read manuals and garages that stock the wrong oil - both of which seem to have little or no understanding of what the numbers on the bottle actually mean (I've noted that some "specialists" in this country have the same issue).

Anyhoo:

By specification: 0w-40 should perform no differently at 100degrees to 5w-40, 10w-40, 15w40, or even old fashioned monograde 40. If anything it should be better, as most 10w-40 oils are semi-synthetic, whilst almost all 0-w40 oils are fully synthetic, and the latter is usually a better quality oil (therefore less prone to breaking down at temperature).

Also, an oil can NEVER be too thin when cold. The average multigrade at 0degrees celsius is well over 1000 times thicker than it is at 100degrees celsius.

Now thats the difference between a glass of water and a cold McDonalds milkshake. Which is easier to suck through a straw? Likewise, think of what a oil pump has to do when trying to push a cold thick oil through narrow oil galleries - some of which are narrower than a straw.

So when cold, a 0w-40 oil will ALWAYS be better than a 10w-40, 10w50, 15w50 or 10w60 etc. And as said, there is little difference between 0w-40 and 5w-40. An issue does exist where 0w oils were not recognised by some car manufacturers and therefore never listed as reccomended oils.

I would have used it myself in my old classic if I stocked it. All I have is 0w-30 Edge, 5w-30 and 10w40 magnasludge. Still, 11 years (and counting) of using the latter seems to have done no harm.

.pslewis. .

I agree that Oil at 0w-40 should perform no differently at 100degrees to 5w-40, 10w-40, 15w40, or even old fashioned monograde 40.

Where I disagree is where you state that you quite happily start your car with water for a lubricant - 0W - your analogy reference water and milkshake is spot on (but the milkshake is 20W or 15W to be honest .... NOT the recomended 10W!)

I would NEVER, EVER put 0W in an engine of mine ..........

Shark Man

The average 10w-40 multigrade at 0degrees celsius is well over 1000 times thicker than it is at 100degrees celsius. That also includes 0w-40 and 5w-40 oils.

A 0w-40's viscosity is around 15cSt (cSt= Centistokes)t at 100degrees - the same as a 10w-40. At 0degrees its about 800-900cSt, whilst a 10w-40 is over 1000cSt

As a point of reference, water at room temperature (20°C ) is about 1cSt, whilst diesel at 20°C is less than 10cst. No automotive oil at 20°C gets even close to that.

.pslewis. . .

I'll take the protection of a 10W all the same

mattdoyle

Sharkman
You seem to know what you are talking about, far more than most on here.

I have been told the mobil 1 is only £26 for 5 litres at costco anyway so it is not that much of a saving.

My car has been modified with a twinscroll conversion, walbro pump, 550 injectors and am putting on a baffled spec c sump(due to the equal headers).

It will be a track day only car and as such will not be doing that many miles, but those it does will be very hard ones.

What viscosity and make would you recommend for it based on those details!!!

cheers

Matt

PS thanks for the informative posts

New_scooby_04

iTrader: (4)

I'm fairly sure that David at APi -who has rebuilt more subaru engines than most, if not all, on here has pretty categorically stated that Subarus don't like 0w oils!

Ns04

Shark Man

Cheers, I've done some exhaustive of reading up, funnily it was all sparked off by the oil debates on here - as everyone had opinions, but little in the way of fact. Track car? I'd suggest something thicker than the above then. As peak oil temperatures will exceed that seen during normal road use - especially when running more BHP. Something worth keeping an eye with a guage.

For hard use, I think you need to be looking at 50 weight oils, so 10w50 or 15w-50 would be more ideal.

As for brand, thats a personal choice. I'm trying not to go into a 3pager with the issue of branded synthetics containing mineral base oils. The main issue is long term durability of the oil at extremes.

Silkolene Pro-s 10w-50 and Motul V300 15w-50 are both oils that are known as "true" esther based sythetics. But are more expensive because of that. Others such as Mobil 15w-50 (or 5w-50 available overseas), or Valvoline VR1 5w-50 are fine, but long term durability maybe more of an issue.

In either case you'll be wanting to do more frequent oil changes.

Millers, Shell and Castrol do a 10w-60 oil. However 10w-60's suitabilty is open to debate. People on here do use it, as do some specialists. But others refuse to use it considering as being too thick when hot; Something I wouldn't argue with, unless the oil temepratures are problem (if so get an oil cooler), and the engine is either worn or built to poor tolerances and/or running high BHP.

mattdoyle

Thanks fella
Forgot to mention on my post that I am putting an oil cooler on it, and that it also has the baffled sump.

I will bin off the offer of the Mobil1, it wasnt that good a deal anyway, and look out for decent 10/50 or 15/50.

Thanks for the info m8.

By the way, how do 'banned' ppl still post????

cheers

Matt

APIDavid

iTrader: (4)

If you put 0W or 5W in an Impreza turbo and drive it the way it is meant to be driven you will break the engine.

Theorise all you like about specifications and esters and all that stuff in oils.

Fact is, we see many, many busted Subaru engines with 0w or 5w oil fitted more so than any other grade of oil.

DON'T DO IT

David APi

Agents for Simtek, the most exciting new Ecu for years

jay knowles

Hi David,does this go for newage and classic engines.Only reason i ask is because ive used 5/40 in my 54 plate sti since its 1000mile service,thanks JAY

APIDavid

iTrader: (4)

I would change oil right now. My advice goes for any Impreza turbo as in ANY.

David

Shark Man

Dave, have you ever considered testing the suspect oils to assertain and back up your conclusions?

When you say 5w, or 0w, do you mean 5w-30? or what? As without the latter numbers which is critical to the specific grades, what you say isn't helping to clear this up one bit. (sorry ).

I only say that as (and I'm going to get knocked for saying this, but...) "on paper" at 100 degrees Celcius these is no difference between a 10w-40 and 5w40 oil, or 0w-40 oil. And out of these, the latter two have higher flash points and higher break down temepratures - i.e they can sustain excessive temperatures better.

You can argue that above 100degrees it maybe different. But I am very certain that 10w-40 oils will fair worse. I belive you mentioned the issues of certain very popular brand 10w-40 oils causing "carbonisation" issues, due to it breaking down at high temperatures over excessive change intervals. So that indeed does back that up. As almost all 10w-40 retail oils are semi-synthetic (with exception to Millers), and consequentally do have lower breakdown temperatures.

Another point is have you ever considered that the most common synthetic grade is 5w-40. And it is the most common off the shelf synthetic oil stocked by garages and motor factors? Any grade other than this that is not a semi-synthetic or mineral grades needs to be sought from more dedicated outlets.

Combine that with the stigma over branding and semi-synthetics, the result is every enthustiastic Subaru owner I meet always opts for the synthetic option (prove me wrong on this ). So statistically alone there is the probability of more cars are running that oil. Couple that with a car prone to having detonation and high temeprature running issues from sensor malfunction, and likely to be abused by its owner or past owners (unknowingly through ignorance) without adjusting oil change schedules or oil grades to compensate. We already know what the outcome will be sooner or later.

Finally, another issue too. Why is 5w-30 listed as an oil for these newage cars by Subaru (UK WRX it actually says 5w-30 preferred)? Now THAT, I do have an issue with: As a note, 5w-30 oils usually are semi-synthetic.

Note its the 30 grade I find the issue here, not its cold "w" rating.


Having said that, most Fords, Vauxhalls, Mercs, VAGs and BMWs as well as Subaru do run 30 grade oils. So what do I know, eh?

APIDavid

iTrader: (4)

I have had a number of conversations with Simon Opie [ Oilman on here ] about all this. We tend to understand each others point of view, but disagree. [ Good naturedly ] He has even sent me breakdowns of constituent parts in oils to show that what I am claiming cannot be correct because the oil spec is so similar.

That is my point; you can theorise all you like about why it shouldn't happen, Fact is; it does.

I have no explanation and he has drummed into me that a 30 oil is always 30 and a 40 is a 40 etc and the lower number is how it behaves at minus 5 degrees or similar. So the relevance of the lower number is nothing like proof.

Neither is the brand any proof. Although during my motorsport life I did a lot of stuff with a racing motorcycle engineer and he used to say that if you ran 4 similar engines on 4 different oils he would be able to pick out the one run on Duckhams, because it was always f*cked. At that time I was sponsored by Duckhams and at the end of the year my Lotus twin cam was f*cked beyond belief - despite fresh oil every race. I got a deal with Castrol for the next year.

We don't bother with the analysis over why and how. It seems far easier to say " don't do that " because history of busted engines at API suggests that 0W or 5W anything [ 30/40/50 ] breaks them.

Regardless of handbook instructions etc.

If you accept my advice that 0w or 5w can cause problems in our experienced opinion, why play Russian roulette??

We regularly repair 15 - 18 engines per month EVERY month so we have some anecdotal input here.

David APi

Shark Man

Fine, I here what your saying: Something very strange must be happening to a 0w-40 or 5w-40 synthetic to make it behave worse than a 10w-40 semi-synthetic. There has to to be a reason.

And thinking of the end consumer here: Its becoming increasingly awkward to buy a synthetic that is NOT 5w or 0w straight off the shelf. And as Subaru becomes a minority car with this oil requirement, its going to get increasingly difficult, as the mainstream trend is going towards 5w and 0w oils.

So as suitable alternatives kept in stock get harder to find (without pre-ordering or buying on-line etc), one does have to question what is causing the problem with the stuff thats always stocked and easy to get hold of.

Furthermore whilst Subaru (and their dealers, respectively) are now listing and putting 5w-30 oils in customer's cars. Potentially, it could be the 30 bit that is more of the issue now than 0w/5w will have ever been. Time will tell when the later newage cars running on 30 grade oil come pouring in.

My experience with 30 grades leads to it being fine when the engine is new and in good condition, but as soon as it suffers wear and tear, oil pressure drops and it starts burning oil. Something to be expected with an overall thinner oil. And we know what eventually happens with Joe Public if thats left unchecked.

The final confusing thing is Castrol's current reccomended oils booklet - supposedly based on OATs data. So whilst it has to be taken with a handful of salt one does have to question how and why they list what they do: Which is pretty much anything newage Subaru be it a 2.0 Sport or 2.5Sti says to use 5w-30 OR 10w-60.

Thats a big difference between grades - the latter of which isn't listed in any of the Subaru manuals either. I've phoned their tech support and it seems I know more about what they sell than they do.

PetesMum

Bottom line is stick with 10W-40 and give 0W and 5W a VERY WIDE BERTH!

Shark Man

So you advise going against Subaru's recomendation of using 5w-30 on post 2000 cars


Edit: Seems whilst my back was turned, Pete's post got vaped...along with his new alias. So just ignore this post.

PetesMum

I'm talking about my car, a Classic 2000, and Subaru say 10W-40

Certainly, a 0W is absolutely NOT recommended for Subaru engines ... isn't that correct?

harvey

iTrader: (48)

On the New Age car which have very tight bore clearances, less than half a thou on standard cars, Subaru recommend for my 02 STi UK 5w-30 or for temperatures above 0 deg.C 10w30 or 10w40. I guess that means during the Winter you should really be running 5w30 and during the Summer either 10w30 or 10w40. In fact I am running Motul 10w40.

I ran the STi 6 Wagon briefly on Royal Purple 5w30 but the oil pressure did seem quite low and while oil consumption was negligible driving normally up to say 4500 rpm I was alarmed that on a return journey to Edinburgh using a good bit higher revs and boost up to 1.85 bar it was possible for the oil level to drop from max to below minimum over the distance of 300 miles.
For that reason I now run all Classics on 10w40 during the Winter, and continue to use that during the Summer if the engine has little wear or normal bore clearance but on worn engines or those with big bore clearances I currently tend to go for Motul 15w50 during the Summer. However, I am about to move back to Royal Purple subject to the viscosity ranges.