2018 WRX Pennzoil ultra platinum 5W30 - 3050 miles

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Just got my first UOA results back for this car. I’ve been changing the oil every 3000 miles to be safe until I was able to do a UOA. At this point with the fuel dilution I’m thinking I shouldn’t go past 3,000 miles.

2018 WRX 2.0 FADIT - Direct injection
CVT

I am not super familiar with all the other numbers. I was mostly concerned with the fuel dilution. If some doesn’t mind letting me know how every thing else looks I’d appreciate it!

This car is my work commuter. It has never seen a short trip since I’ve had it. It does not idle more 5 minutes a day. I park it in my heated garage, and only let it idle leaving work until it comes off high idle. I set my cruise control at 70-73. Does not see any type of excess acceleration or anything like that. My work commute is 35 miles each way. So 70 miles per day with less than 5 miles of that being non highway.

The interesting thing I’ve noticed is the oil temp very rarely gets over 200 degrees. I’m wondering if the temp not getting over 200 is not allowing the fuel to burn off/evaporate. Not sure what to think about the oil temp.

Thanks in advance guys
 

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Stop Idling your car. Get in and fire it up & let it do the dash checks (brakes, air bags, etc). Once the dash lights go off then take off. Second you may be onto something regarding the oil temperature not getting hot enough to potentially burn off the fuel in the oil.

It looks like you might be up north & it's got to be fairly cool there this time of year. There may not be enough warm ambient temps right now to get the oil to burn the fuel. It also may solely be from the idling. That being said I dont think 200 is out of line on this car. Perhaps others can say what theirs runs at.

Everything else looks to be fairly normal, for your mileage of the vehicle, on this report.
 
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You’re doing everything correct to the best of your abilities. The uncontrollable variables are based on engine design. Nothing you can do. Just live with it.

The lack of idle time might actually be making things worse in your case. Excessive idle would build up a ton of heat in the engine bay, perhaps raising the oil temp high enough to burn off fuel and the idling dilution itself wouldn’t be adding anything in the process. 🤷🏻‍♂️
 
The lack of idle time might actually be making things worse in your case. Excessive idle would build up a ton of heat in the engine bay, perhaps raising the oil temp high enough to burn off fuel and the idling dilution itself wouldn’t be adding anything in the process. 🤷🏻‍♂️
Oil heats up when placed under a load, not while idling. If it’s not getting over 200*F with OP’s usage & highway speeds (OP, what’s it turning at 70-73mph? 2800 rpm?) there’s no way in Hades it’s going to get hotter than that just idling.

OP, the only way you’re going to get warmer oil temps it seems is to quit babying it and find some way to work that engine harder! All on-ramps should be WOT once aimed, and push it hard enough to get oil temps 210*F+.
 
We old timers, to get winter engine temperatures up, would partially block the radiator with a piece of cardboard. Remembering to remove it when the weather was warmer.
 
Just got my first UOA results back for this car. I’ve been changing the oil every 3000 miles to be safe until I was able to do a UOA. At this point with the fuel dilution I’m thinking I shouldn’t go past 3,000 miles.

2018 WRX 2.0 FADIT - Direct injection
CVT

I am not super familiar with all the other numbers. I was mostly concerned with the fuel dilution. If some doesn’t mind letting me know how every thing else looks I’d appreciate it!

This car is my work commuter. It has never seen a short trip since I’ve had it. It does not idle more 5 minutes a day. I park it in my heated garage, and only let it idle leaving work until it comes off high idle. I set my cruise control at 70-73. Does not see any type of excess acceleration or anything like that. My work commute is 35 miles each way. So 70 miles per day with less than 5 miles of that being non highway.

The interesting thing I’ve noticed is the oil temp very rarely gets over 200 degrees. I’m wondering if the temp not getting over 200 is not allowing the fuel to burn off/evaporate. Not sure what to think about the oil temp.

Thanks in advance guys
I have a 19 WRXCVT. My oil temperature usually go over 200 but I don’t drive in a lot in the winter. Interesting on the fuel dilution. I average about 1500 miles six months oil changes.
 
Keep in mind PUP is a thin oil to start. I've seen VOAs of 9.5-10 cSt. So despite the high fuel, viscosity loss is not great (at least partially thanks to the short OCI). I agree with the others. The only other thing I'd suggest is to try higher octane fuel. There is some indication that its use in DI engines (even if not required) can help reduce the amount of fuel in the oil because it is more resistant to premature ignition.
 
Keep in mind PUP is a thin oil to start. I've seen VOAs of 9.5-10 cSt. So despite the high fuel, viscosity loss is not great (at least partially thanks to the short OCI). I agree with the others. The only other thing I'd suggest is to try higher octane fuel. There is some indication that its use in DI engines (even if not required) can help reduce the amount of fuel in the oil because it is more resistant to premature ignition.
I run only 93 top tier fuel in this car since I got it about 9,000 miles ago
 
Oil heats up when placed under a load, not while idling. If it’s not getting over 200*F with OP’s usage & highway speeds (OP, what’s it turning at 70-73mph? 2800 rpm?) there’s no way in Hades it’s going to get hotter than that just idling.

OP, the only way you’re going to get warmer oil temps it seems is to quit babying it and find some way to work that engine harder! All on-ramps should be WOT once aimed, and push it hard enough to get oil temps 210*F+.
Today on my drive to work I did a little experimenting.

In intelligent mode at 70 mph it runs 2100 RPM
73 mph it runs 2250 RPM

I tried sport mode. At 73 mph it runs 2600 RPM.

While running sport mode at 73 mph the oil temp went from 196 to 203. It’s also interesting to note that even though I was running a higher RPM my live MPG according to the dash increased from 27 to 29.

I will try to drive only in sport mode for the remainder of this OCI and test again
 
Typical Subaru DIT fuel dilution. It’s probably at its highest during the winter. As others have said definitely do not idle your car. Your engine temps are fairly normal IMO.

You can use the flappy paddles to hold revs higher to warm the car up more quickly, but don’t expect any miracles. You’re not really going to burn off the fuel in a DI engine vs a PI engine.
 
Keep in mind PUP is a thin oil to start. I've seen VOAs of 9.5-10 cSt. So despite the high fuel, viscosity loss is not great (at least partially thanks to the short OCI). I agree with the others. The only other thing I'd suggest is to try higher octane fuel. There is some indication that its use in DI engines (even if not required) can help reduce the amount of fuel in the oil because it is more resistant to premature ignition.

Same sentiment from me. PUP is thin. My Subaru engine (3.6) is pretty easy on oil and a UOA of 7300 miles with 5-30 vast majority highway miles had it at almost a 20 weight. Your engine is substantially harder on oil with turbo & DI. I'd look to a more robust oil and figure out a way to get the temp where you need it.
 
I run only 93 top tier fuel in this car since I got it about 9,000 miles ago
This could be some of the issue. 93 being LESS flammable. 87 octane, being more flammable, will allow it to burn off easier. What does Subaru suggest on octane on this wrx?
 
How hot does the oil need to be to burn off excess fuel in the oil? My WRX is a 2021 and like the OP's car my oil temps are barely over 200 and that's at highway speeds for the most part. 204, 205 maybe? But I admit I only have 3500 miles on it and I only last summer changed the display to read oil temps so I don't have tons of info on it.

You guys bought the right color! World Rally Blue!
 
It's not less or more flammable, it's just less prone to ignition by source other than spark plug and to improper flamefront propagation.

Actually, if you want to get technical. Instead of saying "less prone to ignition source other than spark" you should be saying "less prone to detonation". One of the main purposes of the octane rating is to limit or deter "Detonation".

det·o·na·tion
  • the premature combustion of fuel in an internal combustion engine, causing knocking.
ig·ni·tion
[iɡˈniSH(ə)n]
  • the action of setting something on fire or starting to burn:
  • the process of starting the combustion of fuel in the cylinders of an internal combustion engine:

flam·ma·ble
[ˈflaməb(ə)l]

  • easily set on fire

If 93 is less prone to "Premature Combustion Detonation" I think we can say that limits "ignition" and consequently is less easier set on fire. I think it's safe to say it's "less flammable". Saying "less flammable" is also an easier way of comprehending discussion of "detonation". While I think your wording is a piece to the puzzle it's not the only piece.
 
Actually, if you want to get technical. Instead of saying "less prone to ignition source other than spark" you should be saying "less prone to detonation". One of the main purposes of the octane rating is to limit or deter "Detonation".

det·o·na·tion
  • the premature combustion of fuel in an internal combustion engine, causing knocking.
ig·ni·tion
[iɡˈniSH(ə)n]
  • the action of setting something on fire or starting to burn:
  • the process of starting the combustion of fuel in the cylinders of an internal combustion engine:

flam·ma·ble
[ˈflaməb(ə)l]

  • easily set on fire

If 93 is less prone to "Premature Combustion Detonation" I think we can say that limits "ignition" and consequently is Less easier set on fire than I think it's safe to say it's "less flammable". Saying "less flammable" is also an easier way of comprehending discussion of "detonation". While I think your wording is a piece to the puzzle it's not the only piece.
Are we really going down this rabbit hole?

Octane numbers in the US and Canada are reflected as a function of the AKI (Anti-Knock Index). There are two measuring methods (Research and Motor) and a combination of those two methods are used to derive US/Canada AKI octane numbers (R+M)/2. What is being measured is the fuel's resistance to auto ignition. Controlled combustion (what we are looking for) is the result of the flame front being initiated from a specific point (the spark plug) and propagating across the surface of the cylinder in a consistent manner, producing a controlled and uniform surge of pressure.

I specifically used the wording I did because that's one of the things higher octane mitigates. If you've ever had an old carb'd car run-on after shutting it off, that's the fuel being ignited by an ignition source that isn't a spark (auto ignition), just hot deposits in the chamber. High compression engines are also more prone to knock, which is why they typically call for higher octane fuel. There is also pinging, which is a similar, but different phenomena, the result of the flame front not making it all the way across the chamber. Instead of premature combustion, which can also be violent in addition to uncontrolled, leading to damage (extreme detonation), incomplete or inconsistent flame front propagation can also cause damage, as the pressures in the cylinder aren't consistent and may rock the piston and even lift a ring land.

However, you hold match over 87 and 93 and they are both going to catch fire; they are both equally flammable when exposed to an open flame.

What we are doing with controlled combustion is creating a flame front. In that sense, both fuels are equally flammable; both are going to ignite and burn. 93 isn't going to not ignite just because it's less prone to auto ignition (your original claim that I was responding to).

The reasoning behind people running higher octane fuel in DI engines (and it being effective in some) is because one of the methods of knock mitigation is enrichment (that's why "safe" tunes for turbo/SC cars are pretty rich). DI engines run higher static compression ratios, but part of what precludes them from having to run higher octane despite that is that they have control over WHEN the fuel is injected in the chamber, so pulse width is used not only to enrich relative to load, it's also used to enrich to respond to the knock sensor and since the fuel isn't part of the air charge, it doesn't get heated by the compression stroke. So, if the knock sensor isn't seeing events that it would respond to with enrichment, you end up with a leaner fuel charge and less fuel dilution (in some applications).

Not a universal panacea by any stretch of the imagination, but we have seen UOA's where the results of this methodology are supported.
 
I agree on 95% of what you're saying. You don't equate "Ignition" to a "Flammability" scale. BUT I do so that's where we agree & disagree.

High Compression is what can cause pre-detonation or pre-ignition or pre-combustion at the wrong time. Too early of pre-combustion is mitigated by using a lower volital fuel (Higher octane rating).

I never said that "93 isn't going to ignite". 87 & 93 will both ignite or combust. However, if you put that 87 under a high pressure (Compression) it will ignite or combust SOONER & cause "Pre-Detonation" in an engine. We're not talking about taking a match here & that should be left out. We're referring to use inside of an engine of higher compression or lower compression.

The other big thing for me is when I discuss octane rating it is easier to understand for folks for me to say less flammable / more flammable. As we've demonstrated there is a rabbit hole that could fill our day but it's just easier to say how I stated it & I think it still makes sense. If the 93 octane doesn't combust as easily under compression than I can say it's less flammable too. I'll agree to disagree on what meets my definition of Flammability-Less Flammability for octane ratings & how I can convey that to a forum post in easily digestible simple terms.
 
I agree on 95% of what you're saying. You don't equate "Ignition" to a "Flammability" scale. BUT I do so that's where we agree & disagree.
I use the verbiage I do because with an ICE, when we are talking about ignition, we are talking about either spark initiated ignition (combustion) or auto ignition, which isn't desirable. Flammability (will it ignite if exposed to an open flame) doesn't really enter the picture.
High Compression is what can cause pre-detonation or pre-ignition or pre-combustion at the wrong time. Too early of pre-combustion is mitigated by using a lower volital fuel (Higher octane rating).
Detonation can also be caused by deposits, see: LSPI (super knock). Of course so can pre-ignition. The mixture igniting at any point before the spark plug fires is undesirable, and can cause damage, even catastrophic engine failure. Using a fuel that's more resistant to auto ignition is mitigation mechanism here. I think we are in agreement on that point.
I never said that "93 isn't going to ignite".
What you said was:
fantastic said:
This could be some of the issue. 93 being LESS flammable. 87 octane, being more flammable, will allow it to burn off easier.
Implying that the 93 would be less prone to burn-off (evaporation?) however that's not what we are concerned about with fuel dilution, the fuel isn't being ignited, you are essentially just boiling it off. The auto ignition point of the substance isn't really germane.

87 & 93 will both ignite or combust. However, if you put that 87 under a high pressure (Compression) it will ignite or combust SOONER & cause "Pre-Detonation" in an engine. We're not talking about taking a match here & that should be left out. We're referring to use inside of an engine of higher compression or lower compression.
Any time the mixture is being ignited before the spark plug fires, it's pre-ignition. There are different sources of pre-ignition (too hot of plugs, deposits, too high compression...etc). 87 octane is more prone to auto ignition (which I think we've already established) than 93, which is why traditionally high compression ratio engines have required higher octane fuel. This changed with DI, for reasons I have already explained. The engine in this thread is DI.

As I noted, detonation (knock) and pre-ignition are different phenomena. Both can be damaging. Both can be mitigated by higher octane, but one is essentially combustion starting before it is supposed to (pre-ignition) and the other is an explosive/uncontrolled ignition event which produces a (sometimes massive) pressure spike. This can happen at any time including before ignition and after combustion has started.

Some light pinging (auto ignition of the end gases produced as a result of combustion) is considered normal in certain applications and is controlled by when the mixture is ignited (ignition timing). Igniting it later mitigates it, and this is what is fine-tuned with a knock sensor.
The other big thing for me is when I discuss octane rating it is easier to understand for folks for me to say less flammable / more flammable. As we've demonstrated there is a rabbit hole that could fill our day but it's just easier to say how I stated it & I think it still makes sense. If the 93 octane doesn't combust as easily under compression than I can say it's less flammable too. I'll agree to disagree on what meets my definition of Flammability-Less Flammability for octane ratings & how I can convey that to a forum post in easily digestible simple terms.
We've had the octane tangent on here before as @kschachn I'm sure could attest to, lol.

When I think of flammability I think of it quite literally, as the propensity to ignite when exposed to an open flame. This is why I take issue with its use with respect to comparing octane ratings since, for all intents and purposes, regardless of the fuel's resistance to auto ignition (what the octane number represents) they are all equally inclined to ignite when their vapours are in the presence of an open flame.
 
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