Does maker's oil prescription really maters?

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Esmolante

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"OF COURSE IT DOES!" would be the common answer. Automakers and their engineers knows everything about an engine, and they know better than anybody wich kind of oil fits better. That's right, isn't it?

OK. Let me propose an example. I have a van, a Fiat Ducato with a great 2.3 SOFIM Engine (shared with Iveco Daily). I take the Bible, I mean, the owner's book, and Selenia WR 5W40 (from Petronas) is prescribed. Ok, I know, that's only a marketing policy, there're contracts inked and blablabla. They recomend Petronas as they could do with Shell, Motul, Elf or any other. SFSG. But, I can asume that this oil, from Petronas' portfolio, is the best for my engine. That's right? If I want to choose another brand, I should search for an oil the nearest as possible to Selenia WR and, in any case, a 5W40.

If we have a look to Selenia WR's properties:
Viscosity at 100ºC: 15cSt. So, it's a very thick xW40, almost a xW50.

OK, I have to trust in God's and automaker's word.

But, if I take the owner's book of a DPF Ducato, exactly the same engine, for the first to the last bolt, Selenia WR PE 5W30 is prescribed. And thar oil has...
Viscosity at 100ºC: 10.2cSt. It's a very thin xW30, almost a xW20.

[censored]????
mad.gif


What's the most suitable viscosity for taking care of my engine, 10cSt environ or 15cSt environ? Both can't be correct. I know, any of them is not going to cause heavy damage in my engine, but I was following automaker's prescription in order to achieve the better result. If not, I'd demand my neighbour's oppinion!!!

And taking care of the DPF it's not a reason, because there are plenty of 5W40 that fulfill ACEA C3.

Yes, engineers knows almost everything about engines they design... but engineers don't rule the world (Goldman Sachs rule the world :D).

Sorry for my poor English. I hope it'll be at least understandable.
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Greetings from the rainy side of Spain!
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Originally Posted By: Esmolante
And taking care of the DPF it's not a reason, because there are plenty of 5W40 that fulfill ACEA C3.

In the Selenia/Petronas portfolio (didn't check)?
Also I guess the DPF Ducato is much more recent than the non DPF Ducato, am I right?

Selenia WR used to be recommended to all low duty Italian diesel from ~1999 to 2005-6, before that it was Selenia TD...
 
Welcome to BITOG! And you are correct, the recommended oil for an engine can run the gamut depending on the country it's being used in. I am currently running a 0w-40 in my Ecoboost Ford, which the factory specs' 5w-30. Ford may not be happy with that but the engine is....and that's all that counts!
 
@double vanos: You're answer it's, IMHO, very logical. There're plenty of different circumstances, the weather, the driver, the road, the load... And each advised user must choose an oil to fit his/her particular case.

Anyway, I'd love to know were is the "standard" viscosity or HTHS requirement for, based on them, choosing the best oil IN MY CASE. But, Fiat's (different) recommendation doesn't make it easy.
 
Well, if it's like Renault here in Frogland... in most garages, 5W30 is automatically assumed to be ACEA C2 or C3, for DPF equipped vehicles, and 5W40 is normally ACEA A3/B4, for "other" vehicles. Older than ~2000 cars often get whatever 10W40 they have.


Maybe that's part of an answer? Also do you know when the 5W40 ACEA C3 Selenia was introduced?
 
The answer may be that most engines will be fine with a variety of grades so viscosity may not matter all that much. I'd feel comfortable using either oil in your engine were it mine. Cost does matter at EU oil prices. Is one much dearer than the other?
Add packs matter when you consider aftertreatment systems, most of which don't last well with a high metallic add content oil.
Another consideration might be the intended uses of the various vehicles in which this engine is installed.
A heavier load or faster typical use might mitigate for the use of a thicker oil. HTHS is another and more significant consideration.
 
If it helps always hit the reply button on the post you want to reply to and not the bottom one as that one goes to the op. No big deal but you're asking him the question.

Yes you are correct. I suggested that oil because a certification guy from the Midwest would jump on it and extend the conversation. But you got to it first. lol... Sorry.

Also they make plenty of 229.5 oils and actually can be had directly in the USA for under $22 a jug.
 
I'd be looking at the operating environment. Turbo charged and the driver runs regularly close to the governor? Not turbocharged and it gets lugged around town a LOT... Hilly country and poor fuel? Mostly flat land and good fuel?

Once we know more about the way it's used, we know about what oil MIGHT be better.

But, I'd start with the ACEA rating for the Petronas. Whatever rating's that oil currently carries will tell you what the smallest envelope is. ACEA C3 - if that's it pretty wide open. If it also carries MFG's ratings, add that into the mix.

It was/is obvious that the MFG and the Refiner made a deal to get into the OM. OK, that happens. But they always have to allow for "or equal" among other brands. You just gotta figure out what is "equal" in your market area ...

Once we know that, we can then look in that batch of brands and figure out best properties for your operating environment. If you are in the mountains and doing cold starts; you'll want a lower xW rating, but keep your hot viscosity rating. If you are down in the lowlands and warmer, it's not so much of an issue.

If the driver is famous for lugging the motor, stay with the thicker end of the spectrum. If you are spinning the thing fairly often, you can prolly get away with a bit thinner op vis. If the engine has been modified to make more power, you are back to the thicker end of things ...

Spain or Hungary?
 
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All of the recommended oils have HT-HS greater than 3.5 mPa. With European engines in general, kinematic viscosity have little play.
How about Dexos 2 for FIAT engines in GM chassis? Or Ford Motorcraft oils for PSA units? Or Notorcraft oils for FIRE FIAT engines in Ka? Dynamic viscosity is the most important parameter of oil's physical properties.
 
@Popsy: "Also do you know when the 5W40 ACEA C3 Selenia was introduced?" No, I don't. I see your point. Could be the answer but that doesn't sound very rigorous on the part of FIAT, does it?

"OK, We know the best viscosity is 15cSt, but since Petronas doesn't have an oil 5W40 C3, we choose the only one in his portfolio. Ops! It's a 5W30. Oh, who cares?"
eek.gif


But, it's not only Petronas' oils. The specification FIAT 9.55535-S1 is fulfilled by only C2, thin xW30. So I assume that Fiat thinks it's better a thin oil for that engine. And I want to suppose that the main reason it's not to save a ridiculous 1% of fuel (if that shortens engine's life, is the most stupid saving ever). So, then... was the first statement (5W40 with Ducato 2006-2010 as the better option) wrong?

I stress better, because what the maker has telling you is the optimum. Of course it's possible to use other grades. Even a mineral 20W50 didn't destroy the engine in the short run. But we trust in makers, hoping they prescribe the better (standard) option for its engines, as they know what their requirements exactly are... and I think it's not so... professional, as it should be.
 
Originally Posted By: chrisri
All of the recommended oils have HT-HS greater than 3.5 mPa.


No, they haven't. In fact, Selenia WR PE, Motul Specific S1 or other Fiat-S1 compliant oils has a HTHS=3cP environ. Within ACEA C2, only HTHS>2.9cP is mandatory.

It's enough a HTHS=3cP in my engine? Frankly, I don't know the answer. And I'm very concerned about.
 
@BrocLuno: I agree with you. Starting from the prescribed oil, and I fit it to my circunstances. But, again... what oil? 5W30 or 5W40? 10cSt or 15cSt?

Taking a 5W30 as a good "standard", with heavy loads and hot summers, I can shift to 10W40, f.i.
But if I asumme 5W40 is correct, I should choose an 10W50. Do you see what I mean? I need a reference, and Fiat give me two!

...

NW of Spain. But it's true, there's an homonymous region in Central Europe. "A" in geography.
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Originally Posted By: AirgunSavant

Yes you are correct. I suggested that oil because a certification guy from the Midwest would jump on it and extend the conversation. But you got to it first. lol... Sorry.

Also they make plenty of 229.5 oils and actually can be had directly in the USA for under $22 a jug.

Once again I don't really understand your answer...what's the point?
 
Originally Posted By: fdcg27
The answer may be that most engines will be fine with a variety of grades so viscosity may not matter all that much.


But, then... WTH we are doing here?
laugh.gif


Ok, it's true, it's not SO important. But... we all want the best (at an affordable price) for our engines. The price difference between a can of 5W30 and another of 5W40 of the same brand it's none or irrelevant. So...both, are fine but... what is the best? Is what we're trying to find here, aren't we?

The basis is: oil have to reach a minimum HTHS to secure hydrodynamic lubrication. Above that, there're only minor improvements in wear (and worst milleage and pumpability). So, we have to choose an oil as thin as possible, but above that value for HTHS.

That figure it's not a magic number (3.5...), it depends on the engine, the load, the driver, temperature, altitude, fuel... In order to determine OUR OWN figure, we have to begin from a "standard" HTHS requirement, in "normal" conditions.

The problem IS fiat is giving me two figures, HTHS=3cP (Petronas WR FE --> DPF engine) and HTHS=4cP (Petronas WR --> non-DPF engine). And this doesn't make any sense!

Fiat mocks me
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(and this is only an example with my van, I can tell you the same tale with my Korean car...).

...

BTW: Oil is not so expensive here. I've just bought 5 litres of 5W30 synthetic ACEA C3 VW507 MB229.51... for 18.9€. I translate into usamerican terms: 3.76 $/qt.
https://www.recambium.com/aceite-lubricante-motor/aceite-recambium-synthetic-ll-5w30.html
It's a house brand, actually a Q8 Formula V Long Life rebranded.
wink.gif
 
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