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well we also know from WRX land that the tunes are very rich, wasting fuel among other things. These are just tuned so they are not damaged from any fuel. Stop, because you guys are talking me into another tune. LOL
 

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I get the theory on afr vs timing vs boost. I used to tune my own 2005 Legacy GT with a laptop, looking at knock events etc. I remember the first time trying the tactrix cable, I thought I had bricked my ECU. But all of that was on port injected, not GDI. This is where it becomes a whole new ball game and old-school thinking is obsolete. What the Honda 1.5 TGDI can accomplish on "regular fuel" at 18 psi boost would not have been possible with port injection, so I'm not arguing that my experience with port injection applies directly to TGDI engines. I have no experience with TGDI except for this one, and it's only at 1200 miles.

The Honda 1.5 turbo also suffers from oil/fuel dilution, something that's come up as a possibility with the Subaru 2.4

There's this thing in the Ascent forums about giant clouds of smoke. I'm being paranoid and overly cautious with this relatively new, high compression, GDI turbo engine. Some people wear lucky charms, or do other things that could be considered superstitious nonsense. I use premium fuel, wix xp filters, and frequent oil changes. I don't think it's irrational, but to each his/her own! Nothing I'm doing is against what Subaru has in their manual. My frequent oil changes are for severe service = 3000 miles using thin 0w20 synthetic oil (SN or better) dexos 1 gen 2, SN-Plus. My fuel is 87 or better. I'm going the extra mile on my own time and my own dime, to meet or exceed their specifications.

I'm not at all critical of anyone who chooses to extend oil change intervals, or us regular gas, or use this or that oil filter. I just explain what I do and why. Another person posted a terrific guide to detailing cars. I am appreciative of the post. It explained what was done and why. It doesn't mean that I need to do the exact same thing, or post something contrary. I appreciate when people share their experiences, their thought process, their practices. It's up to me to decide what to incorporate, given the vast knowledge that various people have to share.

Again, this TGDI stuff is new. Old school conventional wisdom may or may not apply. The laws of physics haven't changed, but now we have LSPI to consider. The engine manufacturers themselves are still learning about this cutting edge technology and its potential pitfalls. There is no free lunch. We're in somewhat uncharted territory.

Kudos to Cobb and others are who are actively researching and developing on this new platform. If it weren't for warranty considerations I'd get the Cobb as soon as it comes out. I'd also rip out the carbon filter and use 0w-30 in summer. But I respect the warranty and won't do anything contrary to the owner's manual.
 

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2020 Touring xt
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This low speed pre ignition situation is becoming a really big deal. From what I have read, there isn't any consistency between a minor event and a catastrophic event. Higher octane fuel is only one variable that can help the scenario, although it seems the new SN+ oils are one of the best ways currently to avoid LSPI. Certain additives, like Moly, in a std. SN oil can also help, but it's better to use an SN+, and SN+ oil with the new GM DEXOS ratings are best. GF-6 is possibly going to be out this Spring, so it could all change again... :rolleyes:
 

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This low speed pre ignition situation is becoming a really big deal. From what I have read, there isn't any consistency between a minor event and a catastrophic event. Higher octane fuel is only one variable that can help the scenario, although it seems the new SN+ oils are one of the best ways currently to avoid LSPI. Certain additives, like Moly, in a std. SN oil can also help, but it's better to use an SN+, and SN+ oil with the new GM DEXOS ratings are best. GF-6 is possibly going to be out this Spring, so it could all change again... :rolleyes:
Apologies in advance for derailing octane to talk about oil, but when it comes to LSPI, engine oil may be more critical than fuel octane.

High calcium is associated with a higher probability of LSPI, so the SN-Plus oils have increased magnesium and lowered calcium (calcium still much higher than magnesium).



Using the lowered calcium elevated magnesium formula is supported by Lubrizol's study on aged oils and LSPI:


A total of four oils were tested: a baseline oil – all calcium detergent system (poor LSPI performance); Formulating solution 1 – calcium is reduced and magnesium is added; Formulating solution 2 – molybdenum dialkyldithiocarbamate (MoDTC) is added; and finally Formulating solution 3 – the addition of titanium. The results of the tests found that all three formulation strategies were successful at mitigating LSPI in fresh oil; however, following the aging process, the propensity of LSPI was observed to be very different. Both formulation 2 and 3 showed very poor LSPI durability, while formulation 1 was the only oil to continue to mitigate LSPI when aged.
There's always a caveat about using internet information to form an opinion, so anything you read needs to be taken with a grain of salt and in context of who is providing the information and what they may have to gain.

One source of what's in an oil is to look at used oil analysis where it shows calcium vs magnesium. Zepro Moly's analysis shows high calcium and low magnesium relative to SN-Plus oils. Does the high moly make this ok? I don't know. For now I'm sticking with oils that meet both SN-Plus and Dexos 1 Gen 2, and GF-6 when it comes out. Just my thought process.
 

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So is there a list of those oils in 0w-20?
There is no comprehensive updated list, but almost every major brand (including generics like Walmart/Costco/Amazon) has versions that are both Dexos 1 gen 2 and SN-Plus. You just need to check the specs when you buy - if there's old stock it might not have those specs, so if you're buying in person check the bottle as these formulations may have changed. Since I'm doing frequent oil changes I'm not too worried about getting the absolute best oil - just the cheapest full-synthetic that meets the above specs. It's overkill for sure. Excessive, and money wasting. After the first year of ownership I might stop being so excessive but until the 2.4 has a proven record of reliability I'm going overboard but within the "severe driving conditions" intervals in the warranty & maintenance manual, page 28-29.

When the vehicle is used under severe driving conditions, the engine oil and filter should be changed every 3000 miles or 3 months.

Examples of Severe Driving Conditions
  • Repeated short distance driving
  • Driving in extremely cold weather
  • Repeated trailer towing
 

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2004 Forester 2.5XT 5MT PSM /2020 Outback Onyx XT AGM
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Apologies in advance for derailing octane to talk about oil, but when it comes to LSPI, engine oil may be more critical than fuel octane.

High calcium is associated with a higher probability of LSPI, so the SN-Plus oils have increased magnesium and lowered calcium (calcium still much higher than magnesium).



Using the lowered calcium elevated magnesium formula is supported by Lubrizol's study on aged oils and LSPI:




There's always a caveat about using internet information to form an opinion, so anything you read needs to be taken with a grain of salt and in context of who is providing the information and what they may have to gain.

One source of what's in an oil is to look at used oil analysis where it shows calcium vs magnesium. Zepro Moly's analysis shows high calcium and low magnesium relative to SN-Plus oils. Does the high moly make this ok? I don't know. For now I'm sticking with oils that meet both SN-Plus and Dexos 1 Gen 2, and GF-6 when it comes out. Just my thought process.
But there is also an Idemitsu Zepro that’s SN+/d1 G2 as well. That’s what I’m going with on my first oil change. SoA advised me that the Subaru version is also SN+/d1 G2.

The octane info in the manual is as interesting as the oil info. Light knock going uphill or accelerating is fine, but see your technician if knock is heavy (by then it might be too late). Use 0W-20 for optimum engine performance and the best fuel economy , but a thicker oil is required in high temps. Lots of 2.0 DIT’s are running around with an operating viscosity of a 20 grade anyway. I’m an oil “thicky” in a turbocharged Subaru but maintaining the warranty without hassles is a priority for me.

Coming from an 03 WRX and an 04 Cobb Stage 1 FXT, I’m on the fence about octane. Maybe I’ll mix it up a bit and go with mid-grade to experiment. I always use Top Tier though and usually Shell since its detergent levels are higher than required for Top Tier. We (and Ascent owners) are guinea pigs though in regards to 87 octane in a turbocharged Subaru that specs 0W-20. :eek:
 

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But there is also an Idemitsu Zepro that’s SN+/d1 G2 as well. That’s what I’m going with on my first oil change. SoA advised me that the Subaru version is also SN+/d1 G2.

The octane info in the manual is as interesting as the oil info. Light knock going uphill or accelerating is fine, but see your technician if knock is heavy (by then it might be too late). Use 0W-20 for optimum engine performance and the best fuel economy , but a thicker oil is required in high temps. Lots of 2.0 DIT’s are running around with an operating viscosity of a 20 grade anyway. I’m an oil “thicky” in a turbocharged Subaru but maintaining the warranty without hassles is a priority for me.

Coming from an 03 WRX and an 04 Cobb Stage 1 FXT, I’m on the fence about octane. Maybe I’ll mix it up a bit and go with mid-grade to experiment. I always use Top Tier though and usually Shell since its detergent levels are higher than required for Top Tier. We (and Ascent owners) are guinea pigs though in regards to 87 octane in a turbocharged Subaru that specs 0W-20. :eek:
Thank you for pointing out the manual's discussion of knock - I found it on page 317. My car goes up and down a mountain every week day, and I've never heard it knocking, but it would have to be pretty severe for me to hear it at all.

Fuel should be unleaded and have an octane rating no lower than that specified in this manual.
It sure sounds like "87 is the minimum octane"

Also thanks for pointing out the statement that "in hot weather higher viscosity is required to properly lubricate the engine" found on page 483 of the manual. It doesn't define "hot weather" but I presume ambient temperatures above 90 degrees? Above 100? They leave this unclear. I know that in previous owner's manuals they would have a chart for recommended oil grades for various ambient temperature ranges. Here's it's left vague. I might go ahead and switch to a "higher viscosity" in the summer in accordance with the manual.

I would like to use Idemitsu SN+/d1 G2 oils but they can't compete on price and while I'm happily throwing away money on premium fuel, I'm not going to do it with premium oil. I'm also trying to use Shell whenever I can, but any premium will do. There are always arguments about Shell being great or terrible vs Chevron, but in my region the consensus among subie guys was that Shell is better shrug but this was years ago - I'm not really a part of that scene any more. I know that the same refinery sells fuel to whoever whatever brands are available, and that only the additive packages are different in my area. Shell doesn't have their own refinery here. Circumstances may be different in different parts of the country, which is why it's difficult to generalize experiences in one part of the country with another, regarding fuel. In my area, in my car, it's going to be premium. To be honest I don't trust the refinery here to be consistently at or above their stated grade.
 

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Thank you for pointing out the manual's discussion of knock - I found it on page 317. My car goes up and down a mountain every week day, and I've never heard it knocking, but it would have to be pretty severe for me to hear it at all.



It sure sounds like "87 is the minimum octane"

Also thanks for pointing out the statement that "in hot weather higher viscosity is required to properly lubricate the engine" found on page 483 of the manual. It doesn't define "hot weather" but I presume ambient temperatures above 90 degrees? Above 100? They leave this unclear. I know that in previous owner's manuals they would have a chart for recommended oil grades for various ambient temperature ranges. Here's it's left vague. I might go ahead and switch to a "higher viscosity" in the summer in accordance with the manual.

I would like to use Idemitsu SN+/d1 G2 oils but they can't compete on price and while I'm happily throwing away money on premium fuel, I'm not going to do it with premium oil. I'm also trying to use Shell whenever I can, but any premium will do. There are always arguments about Shell being great or terrible vs Chevron, but in my region the consensus among subie guys was that Shell is better shrug but this was years ago - I'm not really a part of that scene any more. I know that the same refinery sells fuel to whoever whatever brands are available, and that only the additive packages are different in my area. Shell doesn't have their own refinery here. Circumstances may be different in different parts of the country, which is why it's difficult to generalize experiences in one part of the country with another, regarding fuel. In my area, in my car, it's going to be premium. To be honest I don't trust the refinery here to be consistently at or above their stated grade.
Oil temps are MUCH more dependent on engine speeds and such, then outside temps, IME.
I've had oil-temp gauges on several cars, over the years, and they tend to typically just park at one temp, once warmed up, with maybe 10-degree (C) flucuations.
I'm usually more concerned about it being less viscous, faster, at startup, to limit wear when things are chilly (outside).

I worked on a tank-farm, for two summers, and we often traded, between Chevron, Shell, MapCo, Tesero, and others.
There wasn't a single retailer in the area that didn't trade fuel, most at a pretty regular rate (someone would get low, and someone else had just done an offload from a tanker, or gotten a bunch of rail-cars in, etc).
Some of the retailers (Chevron in particular) claimed to be big on the additives. IF they were, they were almost certainly added when the delivery trucks were filled (given the constant churn, some days/weeks). I guess it's possible, but I'm really not all that convinced...
Ultimately, yeah, you might get different refinery-batches, but the chance of getting your retailers' refinery's fuel is basically just a "good marketing tool", more than anything based in reality...
 

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Oil temps are MUCH more dependent on engine speeds and such, then outside temps, IME.
I've had oil-temp gauges on several cars, over the years, and they tend to typically just park at one temp, once warmed up, with maybe 10-degree (C) flucuations.
I'm usually more concerned about it being less viscous, faster, at startup, to limit wear when things are chilly (outside).

I worked on a tank-farm, for two summers, and we often traded, between Chevron, Shell, MapCo, Tesero, and others.
There wasn't a single retailer in the area that didn't trade fuel, most at a pretty regular rate (someone would get low, and someone else had just done an offload from a tanker, or gotten a bunch of rail-cars in, etc).
Some of the retailers (Chevron in particular) claimed to be big on the additives. IF they were, they were almost certainly added when the delivery trucks were filled (given the constant churn, some days/weeks). I guess it's possible, but I'm really not all that convinced...
Ultimately, yeah, you might get different refinery-batches, but the chance of getting your retailers' refinery's fuel is basically just a "good marketing tool", more than anything based in reality...
Yes I agree that oil temps hardly vary at all with ambient temperature and is far more about engine speeds - which is why it's odd that Subaru would make mention about "hot weather" and the word "required". What's interesting is how much viscosity variance is allowed for each weight at 212 Fahrenheit:

SAE 20 5.6 to 9.2 (mm 2/s)
SAE 30 9.3 to 12.4 (mm 2/s)

A "thick" 20wt is said to be Redline. It's scary to think that some 0w20 could have a viscosity of 5.6, and this before any potential oil/fuel dilution. If I recall correctly, Mobil1 is supposed to be a thin 30wt but I'm not sure.

Where I am there's only one gasoline refinery - there used to be two. That's my issue with our gasoline supply. ALL of the gas comes from the same refinery at every station irrespective of brand and only the additive package is different.

Anyways, I'm not sure whether I'm switching to 0w30 in summer - just thinking out loud. I'd be more likely to do it if I could find out the test viscosities of various oils and use a "thin" 30 or a "thick" 20.

This is outdated and scant list, wish they would update it:


They do have separate listings for different oils - the Amazon Basics (what I'm using currently) looks pretty good:


Their full test listing is difficult to use and it's far from comprehensive:

 

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2020 Outback Onyx XT
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But there is also an Idemitsu Zepro that’s SN+/d1 G2 as well. That’s what I’m going with on my first oil change. SoA advised me that the Subaru version is also SN+/d1 G2.
@bluesubie2 Do you know which Zepro 0w-20 formulation is SN plus? I was hoping that one of them was, thinking that’s what I would use, but I haven’t seen that designation on any of them online. They all seem to indicate that they’re SN, as best I can tell. It’s good to hear that the Subaru branded version is SN plus as well.
 

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2004 Forester 2.5XT 5MT PSM /2020 Outback Onyx XT AGM
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@bluesubie2 Do you know which Zepro 0w-20 formulation is SN plus? I was hoping that one of them was, thinking that’s what I would use, but I haven’t seen that designation on any of them online. They all seem to indicate that they’re SN, as best I can tell. It’s good to hear that the Subaru branded version is SN plus as well.
I assumed this was, since it’s d1 G2, but the data sheet doesn’t show it:


It’s hard to say for sure but you can probably contact Idemitsu. Sometimes the oil inside the bottle changes before the label/data sheet is updated. Some oils already meet GF6.

This is from SoA on the Subaru oil. Not sure if this is reflected on the label:


Yes, the Subaru 0W-20 synthetic engine oil for your 2020 Outback Onyx XT meets these specifications - API SN+ and dexos 1 Gen 2.
Mainly I was curious since a VOA on the 5W-30 a few months back still showed high-ish calcium.
 

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Yes I agree that oil temps hardly vary at all with ambient temperature and is far more about engine speeds - which is why it's odd that Subaru would make mention about "hot weather" and the word "required". What's interesting is how much viscosity variance is allowed for each weight at 212 Fahrenheit:

SAE 20 5.6 to 9.2 (mm 2/s)
SAE 30 9.3 to 12.4 (mm 2/s)

A "thick" 20wt is said to be Redline. It's scary to think that some 0w20 could have a viscosity of 5.6, and this before any potential oil/fuel dilution. If I recall correctly, Mobil1 is supposed to be a thin 30wt but I'm not sure.

Where I am there's only one gasoline refinery - there used to be two. That's my issue with our gasoline supply. ALL of the gas comes from the same refinery at every station irrespective of brand and only the additive package is different.

Anyways, I'm not sure whether I'm switching to 0w30 in summer - just thinking out loud. I'd be more likely to do it if I could find out the test viscosities of various oils and use a "thin" 30 or a "thick" 20.

This is outdated and scant list, wish they would update it:


They do have separate listings for different oils - the Amazon Basics (what I'm using currently) looks pretty good:


Their full test listing is difficult to use and it's far from comprehensive:

I believe the oil viscosity info is probably purposely vague for CAFE reasons. If you contact SoA they will tel you to use 0W-20 in all conditions.

M1 5W-30 is actually on the thicker side at 11 cSt’s at 100C, but all Resource Conserving oils have a low HTHS and are designed to shear. A lot of DIT WRX owners have switched to higher HTHS Euro 5W-30’s, but there are no high HTHS options for 0W-20.
 

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A lot of DIT WRX owners have switched to higher HTHS Euro 5W-30’s, but there are no high HTHS options for 0W-20.
Tidbit about the S209:


With the introduction of the STI S209, the most powerful and highest performance STI ever, we want to make you aware of a new high-performance motor oil. To support the 341 HP engine, we are offering the factory fill MOTUL 5W-40 300V POWER 100% Synthetic Racing Motor Oil.
 

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I asked that question 2 months ago. Consensus here ( as I've read in numerous earlier threads) is that there is no value at all in going up in octane. That said, I just got back from a 2 hr highway trip and my XT was off by 1.5mpg (averaging only 27.4). I got gas in a different place this time. ( Cumbies vs Mobile) Wondering if the quality of fuel from vender /brand has an effect. I always heard that they all get thier fills from teh same place and am now starting to question that.
 

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I asked that question 2 months ago. Consensus here ( as I've read in numerous earlier threads) is that there is no value at all in going up in octane. That said, I just got back from a 2 hr highway trip and my XT was off by 1.5mpg (averaging only 27.4). I got gas in a different place this time. ( Cumbies vs Mobile) Wondering if the quality of fuel from vender /brand has an effect. I always heard that they all get thier fills from teh same place and am now starting to question that.

The above list is not necessarily up to date but it's a starting point. My understanding is that each grade of gas is partitioned within the tanker truck, to supply each underground tank's grade of gas independently. Not sure at what point the brand's proprietary additive package is blended in.
 

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I've spent the last hour trying to find information on how good the testing is in various states, and can't find much public info. For example, wouldn't it be good to know if stations in your area have failed their octane tests (or even if octane testing is done?) Fuel issues in one area may not apply in another area, for better or worse. I make my choices partly because of region-specific issues. Ohio seems be be one of the worst - maybe their situation has improved?




 

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This question seems to come up on every car forum Ive belonged to. I already know that because of emission controls your vehicle will run better on the fuel recommended by the manufacture. Its listed in that book that no one ever reads, you know, the Owners Manual. There is always someone who will claim better pick up, more response, faster 0-60, and even better gas mileage. And for those people I say go for it. You can feel better about your vehicle. But why would the manufacture say use 87 octane istead of 90? Wouldnt you think they would tell you to use 90 and not 87?
 
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