2018 Subaru WRX - Oil

Originally Posted by Gokhan
Since they recommend an API SN/SN PLUS/ILSAC GF-5 synthetic 5W-30 for the Subaru WRX or Subaru WRX STI, I would go with a top-quality GM dexos1 Gen 2/Gen 3 5W-30. Either the Mobil 1 Extended Performance 5W-30 or the Mobil 1 Extended Performance High Mileage 5W-30 with its higher PAO content (about a third of the base oil), Group V alkylated naphthalene (AN) content typical of American Mobil 1 oils, and extra antioxidant for extended oil-change intervals is an excellent choice for reducing the intake-valve deposits (IVD) and turbocharger deposits.

The ACEA C2/C3 dexos2 oil with HTHS = 3.5 cP you have is OK to use. It doesn't provide LSPI protection, but I doubt your TGDI engine has a high-enough BMEP to experience significant LSPI events. Subaru didn't bother to require SN PLUS either. Typical ILSAC 5W-30 has HTHS = 3.0 - 3.1 cP, although some have a little higher HTHS.

I wouldn't worry much about some people on oil forums recommending thicker oils. OEMs know what viscosity to recommend better than them. You don't need a higher viscosity unless you're racing etc.



wow so much to learn. I even bought the dexos 2 motul because i "thought" it was one of the best because of the euro standards. I figure if it's good enough for them germans, it's good for import cars. boy i gotta more reading to do.

I went ahead and bought 2 jugs of mobil 1 EP 5w30 as per your recommendation. So far i don't see much negative feedback on it, on various car forums. Only thing is that GM guys don't like it much, because they say it makes their lifters chatter. LS engine guys i mean.

But since its for my subaru, i'll try this out. Thanks again man.
 
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Originally Posted by Virtus_Probi
Originally Posted by Gokhan
Since they recommend an API SN/SN PLUS/ILSAC GF-5 synthetic 5W-30 for the Subaru WRX or Subaru WRX STI, I would go with a top-quality GM dexos1 Gen 2/Gen 3 5W-30. Either the Mobil 1 Extended Performance 5W-30 or the Mobil 1 Extended Performance High Mileage 5W-30 with its higher PAO content (about a third of the base oil), Group V alkylated naphthalene (AN) content typical of American Mobil 1 oils, and extra antioxidant for extended oil-change intervals is an excellent choice for reducing the intake-valve deposits (IVD) and turbocharger deposits.
The ACEA C2/C3 dexos2 oil with HTHS = 3.5 cP you have is OK to use. It doesn't provide LSPI protection, but I doubt your TGDI engine has a high-enough BMEP to experience significant LSPI events. Subaru didn't bother to require SN PLUS either. Typical ILSAC 5W-30 has HTHS = 3.0 - 3.1 cP, although some have a little higher HTHS.
I wouldn't worry much about some people on oil forums recommending thicker oils. OEMs know what viscosity to recommend better than them. You don't need a higher viscosity unless you're racing etc.

It is worth noting that Subaru recalled early WRXs and FXTs with the FA20DIT engine due to LSPI concerns. Some folks got new engines and a lot of damaged plugs were found, supposedly some engine management changes were made through new ECU programming but good luck finding out exactly what they were.
I was feeling pretty good about having started using low calcium/near zero sodium M1 5W30 well before the recall and still want the oils I use in my FXT to have gone through some kind of LSPI testing (dexos1 Gen 1, SN+, Ford -B1). Valvoline AFS 5W30 is d1G2/SN+ as well as high HTHS for a GF5 type oil at 3.2 mPas.



https://sharena21.springcm.com/Publ...bd3/3aa410a1-0bbd-e711-9c12-ac162d889bd1

Agreed...


Capture.PNG
 
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Thanks for the backup, wemay!
Always good to see you on here.
That 10w30 AFS looks nice to me for summer use, but I have a jug of PP 10W30 SN+ already waiting for my next change. Supposed to get a $22 Shell gift card as a rebate for it, hope that SOPUS comes through...
 
BMEP (bar) = 0.125664 × torque (N⋅m) / displacement (liter)

Subaru WRX (350 Nâ‹…m, 1.998 L) BMEP = 22 bar
Subaru WRX STI (393 Nâ‹…m, 2.457 L) BMEP = 20 bar

The higher the BMEP, the more likely the LSPI is. It's interesting that LSPI is reported for this engine. I guess you could start having LSPI events at as little as BMEP = 20 bar. The following was my understanding:

https://www.bobistheoilguy.com/foru...gnition-lspi-and-super-knock#Post5168398

If LSPI is happening in this engine, definitely go with a GM dexos1 Gen 2/Gen 3 oil. If you go with a European oil, make sure it also carries API SN PLUS or API SP or it carries the new ACEA A7/B7.
 
Originally Posted by jimmyturner
Originally Posted by Gokhan
Since they recommend an API SN/SN PLUS/ILSAC GF-5 synthetic 5W-30 for the Subaru WRX or Subaru WRX STI, I would go with a top-quality GM dexos1 Gen 2/Gen 3 5W-30. Either the Mobil 1 Extended Performance 5W-30 or the Mobil 1 Extended Performance High Mileage 5W-30 with its higher PAO content (about a third of the base oil), Group V alkylated naphthalene (AN) content typical of American Mobil 1 oils, and extra antioxidant for extended oil-change intervals is an excellent choice for reducing the intake-valve deposits (IVD) and turbocharger deposits.

The ACEA C2/C3 dexos2 oil with HTHS = 3.5 cP you have is OK to use. It doesn't provide LSPI protection, but I doubt your TGDI engine has a high-enough BMEP to experience significant LSPI events. Subaru didn't bother to require SN PLUS either. Typical ILSAC 5W-30 has HTHS = 3.0 - 3.1 cP, although some have a little higher HTHS.

I wouldn't worry much about some people on oil forums recommending thicker oils. OEMs know what viscosity to recommend better than them. You don't need a higher viscosity unless you're racing etc.



wow so much to learn. I even bought the dexos 2 motul because i "thought" it was one of the best because of the euro standards. I figure if it's good enough for them germans, it's good for import cars. boy i gotta more reading to do.

I went ahead and bought 2 jugs of mobil 1 EP 5w30 as per your recommendation. So far i don't see much negative feedback on it, on various car forums. Only thing is that GM guys don't like it much, because they say it makes their lifters chatter. LS engine guys i mean.

But since its for my subaru, i'll try this out. Thanks again man.

SN+ is not stringent specification at all. It has LSPI test, but that is it.
Euro specification do not need it as LSPI is architecture issue not oil issue. Oil is band aid. VW had LSPI issue on early 1.4 Turbo/compressor engines, but that was 10+ years ago.
Personally, I would stick to Euro specifications in any turbo application.
 
Originally Posted by edyvw
Euro specification do not need it as LSPI is architecture issue not oil issue. Oil is band aid. VW had LSPI issue on early 1.4 Turbo/compressor engines, but that was 10+ years ago.
Personally, I would stick to Euro specifications in any turbo application.

LSPI is a phenomenon caused by oil in high-BMEP and usually smaller TGDI engines.

There are three main factors: (1) BMEP, (2) oil, and (3) how often the engine reaches the maximum BMEP the engine is capable of.

It only happens in TGDI engines with BMEP ~ 20 bar or higher, especially the smaller TGDI engines with such BMEP and/or those with BMEP ~ 25 bar or higher.

They didn't have engines with BMEP in excess of 20 bar until recently. Perhaps the older 1.4 L engine you mentioned was unusual in that it had a very high BMEP, and that's why it had LSPI.

The reason why LSPI has recently come under scrutiny is because the OEMs are pushing the performance and fuel-economy limits and they keep increasing the BMEP to achieve that.

They also have very powerful very high-BMEP engines under production now, but they are less likely to experience LSPI because they are less likely to be pushed to their torque limits.

If you call small high-BMEP TGDI engines an architectural issue, then, OK, LSPI is an architectural issue, but most people wouldn't see it that way, as these engines are being developed to increase the fuel efficiency and performance.

Moreover, two new ACEA specs are being introduced in 2020 to combat LSPI: A7/B7 and C6. Some Euro OEMs are also now incorporating their own LSPI tests.

The paper in this thread is an excellent review article on LSPI:

Review article on low-speed preignition (LSPI) and super knock

PS:

BMEP (bar) = 4π × torque (N⋅m) / displacement (liter) / 100

or

BMEP (bar) = 0.125664 × torque (N⋅m) / displacement (liter)
 
Very interesting and good thread work Gokhan...

I mean that sincerely. .

Very helpful... If and whenever I have to get a newer vehicle.
 
Originally Posted by David2468
Hi folks,

New to the forum, but have read many of the posts over the years. Great information...Thanks all!!

I've been using Castrol Syntec (now edge) for several years on my vehicles (Rav4 V6, VW 1.8T), but have now acquired a Subaru WRX and have been reading a bit, perhaps over reading, and over thinking which engine oil to use. According to spec. it states 5W30 with API-SN, or ILSAC GL4/5 or better. There are several "performance" oils on the market (Motul, Royal Purple, Total etc..) and even the Syntec from Canadian Tire is rated SN as well as Pennzoil, Mobil 1 etc.

Question is, which one is "better" to handle the extreme temperatures of the Subaru Turbo, and the lovely Toronto weather yet to come. Thoughts?

Thanks folks,

SN is outdated.
Use SN Plus and look for Dexos 1 Gen 2 with it.
Pennzoil Platinum, Mobil-1 EP and Valvoline Advanced are solid choices.
 
Originally Posted by Gokhan
Originally Posted by edyvw
Euro specification do not need it as LSPI is architecture issue not oil issue. Oil is band aid. VW had LSPI issue on early 1.4 Turbo/compressor engines, but that was 10+ years ago.
Personally, I would stick to Euro specifications in any turbo application.

LSPI is a phenomenon caused by oil in high-BMEP and usually smaller TGDI engines.

There are three main factors: (1) BMEP, (2) oil, and (3) how often the engine reaches the maximum BMEP the engine is capable of.

It only happens in TGDI engines with BMEP ~ 20 bar or higher, especially the smaller TGDI engines with such BMEP and/or those with BMEP ~ 25 bar or higher.

They didn't have engines with BMEP in excess of 20 bar until recently. Perhaps the older 1.4 L engine you mentioned was unusual in that it had a very high BMEP, and that's why it had LSPI.

The reason why LSPI has recently come under scrutiny is because the OEMs are pushing the performance and fuel-economy limits and they keep increasing the BMEP to achieve that.

They also have very powerful very high-BMEP engines under production now, but they are less likely to experience LSPI because they are less likely to be pushed to their torque limits.

If you call small high-BMEP TGDI engines an architectural issue, then, OK, LSPI is an architectural issue, but most people wouldn't see it that way, as these engines are being developed to increase the fuel efficiency and performance.

Moreover, two new ACEA specs are being introduced in 2020 to combat LSPI: A7/B7 and C6. Some Euro OEMs are also now incorporating their own LSPI tests.

The paper in this thread is an excellent review article on LSPI:

Review article on low-speed preignition (LSPI) and super knock

PS:

BMEP (bar) = 4π × torque (N⋅m) / displacement (liter) / 100

or

BMEP (bar) = 0.125664 × torque (N⋅m) / displacement (liter)

Which Euro engine has an LSPI problem?
New ACEA calls for LSPI testing due to newcomers from Asia etc. which have issues based on lack of experience with engines like this.
What you posted does not help anyone looking for an answer which oil to use in their turbo engine.
Give yourself few years, you might catch up with Euro engines.
 
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Originally Posted by edyvw
Which Euro engine has an LSPI problem?
New ACEA calls for LSPI testing due to newcomers from Asia etc. which have issues based on lack of experience with engines like this.
What you posted does not help anyone looking for an answer which oil to use in their turbo engine.
Give yourself few years, you might catch up with Euro engines.

LSPI is a concern for the Euro OEMs as well. That's why ACEA A5/B5 is being replaced by ACEA A7/B7.

For example read and watch the video discussion by PSA Peugeot Citroen, which has introduced its own LSPI test:

PSA looks for the right balance

Video transcript: "The current LSPI tests look at the propensity of a new engine oil to create LSPI events. But in fact it is a bath curve. At the first kilometers it is possible for an engine oil to create reactive species due to mechanical and chemical shearing. But the ageing of the engine oil and higher pressure increase in the combustion chamber creates more LSPI events. Moreover the dispersant detergent nature can impact the number and the size of the fuel/ engine oils droplets and so the LSPI events. That's why Groupe PSA developed a LSPI test, which covers all the different driving life which generate LSPI in the field and with aged oils."
 
Originally Posted by Gokhan
Originally Posted by edyvw
Which Euro engine has an LSPI problem?
New ACEA calls for LSPI testing due to newcomers from Asia etc. which have issues based on lack of experience with engines like this.
What you posted does not help anyone looking for an answer which oil to use in their turbo engine.
Give yourself few years, you might catch up with Euro engines.

LSPI is a concern for the Euro OEMs as well. That's why ACEA A5/B5 is being replaced by ACEA A7/B7.

For example read and watch the video discussion by PSA Peugeot Citroen, which has introduced its own LSPI test:

PSA looks for the right balance

Video transcript: "The current LSPI tests look at the propensity of a new engine oil to create LSPI events. But in fact it is a bath curve. At the first kilometers it is possible for an engine oil to create reactive species due to mechanical and chemical shearing. But the ageing of the engine oil and higher pressure increase in the combustion chamber creates more LSPI events. Moreover the dispersant detergent nature can impact the number and the size of the fuel/ engine oils droplets and so the LSPI events. That's why Groupe PSA developed a LSPI test, which covers all the different driving life which generate LSPI in the field and with aged oils."

Sure it is concern. If it was not concern you would have bunch of LSPI incidents in Euro turbo engines. However, you do not, precisely bcs. it is concern. SN+ is band aid. Oil is band aid. This is where experience pays off, as no one has experience with small turbos as Euro manufacturers. VW had issues with LSPI in first gen. 1.4 turbo/compressor engines. However, they quickly resolved that without introducing any new oil specification.
 
Originally Posted by edyvw
Sure it is concern. If it was not concern you would have bunch of LSPI incidents in Euro turbo engines. However, you do not, precisely bcs. it is concern. SN+ is band aid. Oil is band aid. This is where experience pays off, as no one has experience with small turbos as Euro manufacturers. VW had issues with LSPI in first gen. 1.4 turbo/compressor engines. However, they quickly resolved that without introducing any new oil specification.

LSPI is by definition oil-caused preignition. The oil is not Band-Aid here. It's the perpetrator. If it's not being caused by the oil, it's not LSPI.

You're talking about one data point ten years ago. A lot has changed in ten years in terms of the BMEP. The real danger zone for LSPI starts at BMEP = 25 bar. The BMEP for the VW 1.4 L engines range from 18.1 bar to 22.6 bar, depending on the specific engine model. They don't enter the LSPI danger zone (BMEP ⥠25 bar). Therefore, Volkswagen has not figured out or solved anything regarding LSPI.

In contrast the PSA EB2ADTX engine (1.2 L, 240 Nâ‹…m) has BMEP = 25.1 bar. These days they even make engines with BMEP ~ 27 bar. As the BMEP gets higher and higher to improve the fuel economy, LSPI will become more and more of an issue, and oils will need reformulation to combat the problem.
 
Whatever is known to Volkswagen is known to every OEM in the industry.

The review article lists the following to mitigate (1) the occurrence of LSPI events and (2) occurence of super knock following the LSPI events if LSPI events occur. They all help and are known and available to every OEM in the world, not just Volkswagen or some other Euro OEM. Click the link for the full section with figures.

Section 5.2. Control strategy for super knock -- Zhi Wang et al., Tsinghua University, China

---------------------------------------------------------

5.2. Control strategy for super-knock
As reviewed in this article, there are two ways to avoid super-knock. One is to eliminate pre-ignition. The other is to decouple the shock wave and the heat release.

To suppress pre-ignition, the following factors should be established.
1) Oil intrusion: Oil intrusion into the combustion chamber can be reduced by using a larger chamfer piston edge [153], increased oil ring tension [224] or optimized ring orientation [324]. Use of a low volatility oil [153] and improved oil ventilation [197], [324] are also helpful.

2) Oil/fuel mixing: Avoiding oil/fuel mixing in a gasoline direct injection engine can be achieved by adjusting the spray direction to reduce liner wall wetting, by employing a split injection strategy [153], [204], [325], or by adopting high tumble to enhance air motion [151] to reduce spray penetration.

3) Oil properties: Optimized oil formulations, including use of low calcium [152], [324], [326], Na [326], sulphated ash [227], and high ZnDTP [152] and MoDTC [147] oils.

4) Fuel properties: Optimized fuel formulation, including low aromatics [201], [232], high ethanol addition [201], and low volatility [151], [193], [202].

5) Solid particles: Reduced flammable particles floating in the combustion chamber, including deposits [220], [222], soot [204], and metal dusts [148] Fe, Cu, etc.

6) Combustion system: Optimized engine combustion systems to reduce end-of-compression temperatures by enriching the mixture or promoting gasoline evaporation via direct injection, or scavenging of the hot residual gas [214], [327]

To suppress super-knock with a pre-ignition, the following factors should be established:
1) Adopting high octane fuels with higher laminar flame speeds, for example, gasoline/alcohol blends [3].

2) Optimized fuel formulations, including fuels with low aromatic content [149], [201], [202].

3) Decrease reactivity of the unburned mixture, by introducing cooler EGR [213], or ignition inhibitors as fuel additives, or even spraying water.

4) Increase mixture gradients by dual fuel direct injection to achieve fuel stratification [156].

Some practical solutions have been applied in gasoline engine production to control super-knock, and are summarized as follows:

Cooled EGR
...

Scavenging
...

Injection strategy
...

Integration of high tumble-high EGR-Atkinson/Miller cycle
...
 
Originally Posted by bbhero
Very interesting and good thread work Gokhan...

I mean that sincerely. .

Very helpful... If and whenever I have to get a newer vehicle.

Thank you for your kind words, bbhero. It's an interesting subject indeed.
 
So after about a month with the Mobil 1 EP 5w-30, i am switching it out this weekend to PUP. I should have did more reading on my car specifically, it seems that mobil 1 is one of the "worst" oils for the fa20 engines, or subaru engines in general. The past 2 weeks i hear a lot of engine chatter. Not knocking noises, but loud valvetrain noise. I don't know what it is but i usually hear it only when the engine is fully warmed up. I know i shouldn't worry becasue the car as a warranty but it's the inconvenience of doing the whole back and forth to the dealer, especially during this pandemic.

Mobil 1 EP is great oil, as i use it in my other car. But on subaru, not so much.
 
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Originally Posted by jimmyturner
So after about a month with the Mobil 1 EP 5w-30, i am switching it out this weekend to PUP. I should have did more reading on my car specifically, it seems that mobil 1 is one of the "worst" oils for the fa20 engines, or subaru engines in general. The past 2 weeks i hear a lot of engine chatter. Not knocking noises, but loud valvetrain noise. I don't know what it is but i usually hear it only when the engine is fully warmed up. I know i shouldn't worry becasue the car as a warranty but it's the inconvenience of doing the whole back and forth to the dealer, especially during this pandemic.

Wow that is something that a different brand could cause all that. Pandemic and all.
 
Originally Posted by jimmyturner
I should have did more reading on my car specifically, it seems that mobil 1 is one of the "worst" oils for the fa20 engines, or subaru engines in general.

Mobil 1 EP is great oil, as i use it in my other car. But on subaru, not so much.

Sorry but that's complete nonsense. M1 got a bad rap in the Subaru community from knuckleheads having issues modifying their cars to 400 hp and continuing to use the oil viscosity recommended in the owner's manual. Just because the oil is noisy doesn't mean that there is an issue with your engine.

There are a lot of EJ's out there with good results on M1 0W-40 and lots of FA20DIT's with good results on M1 5W-30 ESP. Here's a FA20DIT thread with some M1 uoa's.

https://forums.nasioc.com/forums/showthread.php?t=2657990
 
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