[Trey T]

Going only by the dash-top display, the oil temperature varies significantly. During colder weather, the oil temperature may never rise above 160 deg F, even on a 10+ mile trip. During warmer weather, it's usually up between 190 and 200 deg F. It may go up to 220 deg F or so during a long hill climb where engine speeds are elevated.

Engine speed is the biggest contributor to oil temperatures, at least in my experience. If I idle the car around in CVT mode all day, the oil temperatures may stay low for a while. But if I keep the engine spun up in manual mode, oil temperatures will rise quicker. Even in cold temperatures.

I would say "normal" temperature of our engine oil is about 190 deg F. Again, indicated by the dash-top display. Of course, temperatures at the bearing interfaces or just after will be much higher. Temperatures in the pan may be lower. I'm not exactly sure where in the system the temperature sensor is located, but that'd be interesting knowledge to have.

Mine is at 212degF (100degC) like 30%+ of the year, during warm/hot season. We don't need to know precisely where the oil temp sensor is at because your coolant is always get regulated around 195degF (90degF) by the thermostat. So your oil temp will always be higher on average than the coolant. For "casual conversation", the oil temp is always experiencing ~100degC.

 

[hokiefyd]

It sounds like there's a bit of variability in the oil temperature different engines see. Ours, for example, almost never reaches an indicated 212 deg F. It does, on occasion, get above 200 deg F, but it will generally cool back down to the mid-to-upper 190s after that.

 

[Joe Mama]

At the risk of reviving a zombie thread, here goes:

I ran across this chart that claims to list the temperature ranges of different weights of oil.

Valid information, or bogus?

"If you look at an oil chart (given below), you will see the both 0W20 and 5W20 are in almost the same spectrum.

Oil viscosity and temperature chart. (Photo Source: pakwheels)
0W20’s range is from -40° to 20° while 5W20’s is from -25° to 20°. "

Seems like the upper ambient temperature range is VERY low. As in 68 degrees F.

 

[Robert.Mauro]

I'd ignore the chart. Here's Idemitsu's temperature and viscosity data for their full synthetic 0-W20:
(Subaru oil is made by Idemitsu)

And here's the temperature range chart for the oil they require:

 

[hokiefyd]

At the risk of reviving a zombie thread, here goes:

I ran across this chart that claims to list the temperature ranges of different weights of oil.

Valid information, or bogus?

In general, the information presented there correlates with how different viscosity grades work, but oil viscosity is a very application-specific science. Water-cooled engines typically run at relatively consistent temperatures, with the cold start temperature being the primary concern. There's really no practical upper temperature limit because the engine's running temperature is thermostatically controlled. That is, the engine's fully warmed-up running temperature doesn't depend on the outside temperature -- whether it's 50 deg F or 115 deg F outside, the engine temperature and oil temperature will be relatively comparable.

I'd wager that chart above may be more relevant to an air-cooled engine application, where engine and oil temperatures will vary widely depending on outside air temperature.

 

[Joe Mama]

I'd ignore the chart. Here's Idemitsu's temperature and viscosity data for their full synthetic 0-W20:
(Subaru oil is made by Idemitsu)
View attachment 12819

And here's the temperature range chart for the oil they require:
View attachment 12820

If 5W-30 conventional oil is an acceptable temporary substitute, would it not follow that 5W-30 synthetic oil would be a superior substitute (to the conventional oil)?

 

[hokiefyd]

If 5W-30 conventional oil is an acceptable temporary substitute, would it not follow that 5W-30 synthetic oil would be a superior substitute (to the conventional oil)?

I think they recommend conventional 5W-30 as an acceptable temporary substitute as it's a widely available and inexpensive product if 0W-20 cannot be sourced. Sure, synthetic would be considered superior. However, there's really little benefit in spending extra money on synthetic oil if it's only for temporary use, to be replaced with the more optional stuff in short order.

 

[cme4dk2]

I just bought the oil pump for taking the oil out from the top without even doing the valve at the bottom. That plus the filter on top should mean a 5 min oil change with little/no mess! I've always done my own changes but now it'll be even easier. Also means I can do it more often if I feel like it!

What oil pump is that?

 

[Joe Mama]

I think they recommend conventional 5W-30 as an acceptable temporary substitute as it's a widely available and inexpensive product if 0W-20 cannot be sourced. Sure, synthetic would be considered superior. However, there's really little benefit in spending extra money on synthetic oil if it's only for temporary use, to be replaced with the more optional stuff in short order.

Considering the price of these vehicles is $37K - $50K, the extra $3 per quart for synthetic over dino shouldn't be a deal breaker. 🙂 I actually find conventional oil to be in the minority on the shelves, anyway.

 

[hokiefyd]

Considering the price of these vehicles is $37K - $50K, the extra $3 per quart for synthetic over dino shouldn't be a deal breaker. 🙂 I actually find conventional oil to be in the minority on the shelves, anyway.

I don't think it's the price difference itself they're avoiding. If you're deviating from the recommended 0W-20, you're supposed to be at your last resort. They're recommending something to get you home, or to get you back to the dealer, etc. To most city slickers, 0W-20 is as readily and widely available as any other grade. In that case, none of this discussion matters at all. When 0W-20 is available, Subaru recommends we use it. If you can't find 0W-20, then you likely can't find a lot of other oil selections either. Conventional 5W-30 is about the most basic of an oil spec you'll find in North America and nearly every roadside stand will have at least something in this grade.

I think that's the bottom line -- it's for those worst-case situations when you're out in the middle of nowhere and find the engine to be a quart low...what do you use? In this case, find any basic 5W-30 that meets SN/GF-5 (which is going to be any brand name 5W-30) and use that to get you home. Put 0W-20 back in at the next recommended oil change interval and keep driving.

 

[maiden7705]

Hey all, so, I reached out to SoA again, and they say they most definitely fully intend for 0W-20 to be used in the Ascent, except for occasions where it's not available to top off low oil, in which case 5W-30 can be used and swapped out at the next oil change.

To SoA:


From SoA:


No matter how many times I ask them, no matter how many ways, no matter through which point of contact, the answer is the same - "we meant it, use 0W-20 unless you absolutely don't have it and need to add oil, in which case use 5W-30 temporarily" and the implication that "it's possible" that some types of failure may be deemed related and thus cause uncovered warranty claims, but that will be determined on a case by case basis.

So, do what you wish... but be aware that four times so far, via multiple channels, I've gotten responses indicating the above in one form or another.

Yeah i would have stuck with factory weight no questions asked, except I have quite a few (like 10-20 qtz) of discount bought 5W-30 sitting in my garage.

 

[maiden7705]

0W-20 has a better oil base than most 5w-30s anyways from what i understand and you could probably get away with running 0w-16 or 0w-8 as they do in Japan more than other countries and same could be said for 5w-30....the only problem i see with running 5w-30 is more wear at cold starts when temps drops and more load on engine which could cause to run hotter and get less MPG. I don't think running 5w-30 syn would cause any major issues within 100k, but why take the chance and the main advantage of lighter weight oils seems to be MPG and cold weather starts??

I don't think it will be long before we see 0w-8 come filled from the factory in compact cars and maybe even the Ascent to get those MPG numbers to creep up.

My only confusion on this whole oil matter is: I live in california, does a cold start of 5 vs 0 really matters for me? so it comes down to whether viscosity of 30 is better at normal running temperature or 20?

 

[Jim_in_PA]

maiden7705, you should be able to off-load the extra oil you have in personal inventory by selling it locally on one of the "lists" (FB Marketplace, Craig's List, etc) and pick up the specified weight that the engine was designed to use. That way, you stay within the Subaru guidelines and there will never be the potential for questioning things should you have an issue. The fact that the 5W is permitted "in a pinch" means just that. I doubt Subaru want you to repeat it simply because you have many quarts of it easily available. Try to think like the manufacturer for things like this that can have warranty claim implications.

 

[hokiefyd]

My only confusion on this whole oil matter is: I live in california, does a cold start of 5 vs 0 really matters for me? so it comes down to whether viscosity of 30 is better at normal running temperature or 20?

Engine manufacturers recommend a grade of engine oil based on its viscosity measured at operating temperature, or about 100 deg C. As oil cools from that, it thickens. An oil with a lower "W" number (such as 0W vs. 5W) will thicken less as the temperature of the oil drops. In other words, a 0W-20 will stay at a lower viscosity longer (as its temperature drops) than a 5W-20 oil will. You want the oil to thicken as little as reasonably possible, because this increase in viscosity makes it harder for the engine to pump, creating friction, increasing fuel consumption, etc. And to answer your question directly, this matters, even in California. It certainly matters more to someone in Canada, but even southern Californians and southern Arizonians don't need to have unnecessarily viscous oil in their engines.

Viscosity of Engine Oil – viscosity table and viscosity chart :: Anton Paar Wiki (anton-paar.com)

Those charts will give you a relative idea of how much an oil thickens. 0W-20 is not featured there, but 0W-30 is, and we can use that as a representative sample, acknowledging that the numbers aren't exactly the same as what they'd be for a 0W-20. Scroll down to the 0W-30 chart and look at the kinematic viscosity column. The units are centistokes and the scale is linear - 50 centistokes is twice as viscous as 25 centistokes. 0W-30 has a kinematic viscosity of about 15 cSt @ 90 deg C (which is nearly operating temperature). But look at its viscosity at 30 deg C (or 86 deg F -- a southern California cold start): over 100 cSt -- nearly 7 times as viscous as the oil is at operating temperature!

Again, those aren't 0W-20 numbers, and I didn't find anything with a casual search, but the concept remains the same -- the oil will thicken dramatically as the oil's temperature falls, and you want to minimize this as much as you reasonably can.

 

[Merope]

... I have translated this page for everyone:...
0w-20 "eco"
High oil temperature engine protection - 2/5 (yikes!)...

What's Japanese for "yikes"?

 

[packout]

Note that the viscosity grades for oils (the "20", "40", etc.) represent measured viscosity ranges at certain temperatures (at 100*C, actually). Your engine oil is almost never at exactly that temperature. In fact, our engine oil very often never does get that warm (at least indicated on the dash-top display). Temperature will certainly vary throughout the engine (in the pan, in a journal, at the bearing surface, etc.), but we can go only with what we can directly observe, at least for a casual conversation like this.

But again, the grade number represents a range of viscosity units...it's not the viscosity itself. A 20 grade oil (such as a 0W-20 or a 5W-20) must have a viscosity of between 5.6 and 9.3 cSt (centistokes) at 100*C. At only 60*C, or 80*C, the actual measured viscosity of a 20 grade oil will be higher, probably in the 10-12 cSt range. The viscosity range of a 5W-20 will increase faster as it cools than a 0W-20 will. A 40 grade oil must have a viscosity of between 12.5 and 16.3 cSt at 100*C. Again, at lower temperatures, it'll be even higher than that. It's not like the engine will blow up with a thicker oil. Even a 0W-20 is way too thick at startup to be optimal (hundreds of cSt probably, depending on the temperature).

Subaru says clearly that a 30 grade oil is acceptable, but that a 20 grade oil should be used at the next opportunity. I believe they say this because 0W-20 was used during fuel economy certification and they're required by law to recommend the same oil be used during service. This is to avoid using something like a 5 grade oil for fuel economy testing and then filling and recommending a 30 grade oil for longevity.

Interesting aside: when 20 grade oils first started appearing, people would say that they're "thin like water", especially with a hot drain. They're actually not. Water has a viscosity of about 1 cSt at 18*C. At 18*C, when a 5W- or a 0W-20 is measured in the hundreds of cSt, water's at 1 cSt.

 

[Jim_in_PA]

Why does that dude look like Jim Carrey?

 

[Fergie]

Figured I'd add my 2 cents into this. I have been monitoring my oil since 1000 miles. Drained the factory oil at 1k and put Mobil 0w20 EP (Extended Performance) in since it is a fantastic oil and readily available. However, I noticed that it was shearing down by a lot and this is with less than 5k mile OCI's. It was basically falling into a new 0w16. From my research, there is no other vehicle that has sheared this oil this much, even over 10k mile OCI's. So I went ahead and tried Mobil 0w30 AFE and 0w30 ESP. I like the ESP more and will likely continue using that. While I know it doesn't specify API SN/SN PLUS, it holds higher standards than API or ISLAC require. Here are my test results below. This is also posted in the UOA thread.