This analysis is from a USDM 2005 STi with 13,185 miles. The sample collected had 5,685 miles of use. The oil I used was Castrol Syntec 5W/30.

Universal averages show typical wear metals for an oil from this type engine after about 4355 miles run on the oil. Your oil was in use 5685 miles, and we found all wear at around average levels and in the correct balance to show normal mechanical parts inside. Air and oil filtration appear normal. No fuel, moisture or anti-freeze was found. Viscosity was in the SAE 20W range but it didn't hurt anything. The TBN was 2.3, some additive left, 1.0 is low. Nice wearing engine. Try 6500 miles for the next sample and check back to establish wear trends.

That is the only thing that concerns me, thinning to 20W at high temps. I wonder if I should try a different brand oil or continue using the same brand/type to establish wear trends?? I wonder why it would change??

And as I have said MANY times before, there is no need to change your oil as often as some people say. This is "proof" of that. My .02.

This analysis is from a USDM 2005 STi with 13,185 miles. The sample collected had 5,685 miles of use. The oil I used was Castrol Syntec 5W/30.



That is the only thing that concerns me, thinning to 20W at high temps. I wonder if I should try a different brand oil or continue using the same brand/type to establish wear trends?? I wonder why it would change??

And as I have said MANY times before, there is no need to change your oil as often as some people say. This is "proof" of that. My .02.

If the viscosity is a 20w, doesn't that mean the 5w thickened to a 20w at cold temps?

Not a 30 thinning out to a 20 at hot temps?

If you want to switch oils, you can also try GC (German Castrol), Castrol Syntec 0w-30 :D

If the viscosity is a 20w, doesn't that mean the 5w thickened to a 20w at cold temps?

Not a 30 thinning out to a 20 at hot temps?

If you want to switch oils, you can also try GC (German Castrol), Castrol Syntec 0w-30 :D

Oil is designed to actually thicken with the engine temp. This allows circulation for cold start and the thicker protection once the engine is running....

So the viscosity is a low 5w (thinner) when you start the engine up. When your engine is warm in a few minutes then its 30w (thicker)

.....

Was the oil tested to be 20w while cold or hot? If it was while it was cold (most likely) then it wont circulate as fast on start up. If it was when it was warm then I'd switch oil since its not as advertised.....

You have 13k miles on the car. I wouldnt be surprised if its not still shedding engine material into the oil on a microscopic scale. Of course it will always do this but I think your test will show up looking even better when you have 20k on the car.....

Also after seeing tons of oil analysises I'm convinced the only difference between Mobil 1 0w-30 and Mobil 1 5w-30 is the color of the cap on the bottle..... :) :)

That is the only thing that concerns me, thinning to 20W at high temps. I wonder if I should try a different brand oil or continue using the same brand/type to establish wear trends?? I wonder why it would change??

It's not unusual at all for a 5W30 Group III oil being ran in a 2.5 turbo to shear out of grade. That's why the lab even recommends to go longer on the next interval. If more people would have an oil analysis performed they would see this happens with a lot of oils. There are thousands of Subes running around with 20 weights and don't know it. People have said a bajillion times (I counted them :p ), 5W30 is recommended for fuel economy and a higher viscosity is required for higher temps and different driving conditions.

What's the viscosity number (SUS, Cst)? Do you have a link to the full report?

If anyone wants peace of mind, run a thicker oil or one with some ester synthetic basestocks like German Castrol 0W30, Motul 300V etc.
Here's my last analysis on German Castrol with 6,100 miles. (http://forums.nasioc.com/forums/showthread.php?t=867745&referrerid=767) Note that the viscosity is a high 30 weight. I'm running my current fill to 7,500 miles and I'm pretty confident it will still be well in grade.

Read this more more info on oil viscosity. (http://www.advanceautoparts.com/english/youcan/html/ccr/ccr20040601ov.html)
-Dennis

Oil is designed to actually thicken with the engine temp. This allows circulation for cold start and the thicker protection once the engine is running....

So the viscosity is a low 5w (thinner) when you start the engine up. When your engine is warm in a few minutes then its 30w (thicker)
Err, oil doesn't thicken as temperature goes up ;)
Oil still gets thinner as temperature rises.

The link bluesubie posted is a good read.

The 5w refers to the oil's viscosity at really cold temps.
The 30 refers to the oil's viscosity at 100c.
Even though 30 is bigger than 5w, it doesn't mean the oil gets thicker as temp increases.

Don't wanna make things more confusing, but here we go...
Yes, you want a thin oil at start-up. But thin relative to what?
Our engines (and most) were designed to use a 30 weight oil at operating temperatures.
So why not use just a straight 30 weight oil (SAE 30)?
I'm pulling some real rough numbers here:
100c
SAE 30 ~11 cST
10w-30 ~11 cST

20c (A nice day)
SAE 30 ~350 cST
10w-30 ~130 cST

A SAE 30 is really thick at start-up compared to a multi-grade oil (5w-30 or 10w-30) It gets even worse at colder temps. I think viscosity is exponentially proportional to temperature.

So back to the point, we do want a thinner oil at start up. But the "thin" is being compared to a single-grade oil (SAE 30 or SAE 40 etc).
Many FAQs say "You want a thin oil for start-up" without a point of reference!

If you're confused, let me know. I'll try to explain it better.
I had the exact same understanding you did until I started reading more.

Was the oil tested to be 20w while cold or hot? If it was while it was cold (most likely) then it wont circulate as fast on start up. If it was when it was warm then I'd switch oil since its not as advertised.....
That's what kinda confused me... if it's a 20w, that means it was tested at cold. If it was just a 20 (no w), that means it was tested at 100c.

Err, oil doesn't thicken as temperature goes up ;)
Oil still gets thinner as temperature rises.

The link bluesubie posted is a good read.

The 5w refers to the oil's viscosity at really cold temps.
The 30 refers to the oil's viscosity at 100c.
Even though 30 is bigger than 5w, it doesn't mean the oil gets thicker as temp increases.

Don't wanna make things more confusing, but here we go...
Yes, you want a thin oil at start-up. But thin relative to what?
Our engines (and most) were designed to use a 30 weight oil at operating temperatures.
So why not use just a straight 30 weight oil (SAE 30)?
I'm pulling some real rough numbers here:
100c
SAE 30 ~11 cST
10w-30 ~11 cST

20c (A nice day)
SAE 30 ~350 cST
10w-30 ~130 cST

A SAE 30 is really thick at start-up compared to a multi-grade oil (5w-30 or 10w-30) It gets even worse at colder temps. I think viscosity is exponentially proportional to temperature.

So back to the point, we do want a thinner oil at start up. But the "thin" is being compared to a single-grade oil (SAE 30 or SAE 40 etc).
Many FAQs say "You want a thin oil for start-up" without a point of reference!

If you're confused, let me know. I'll try to explain it better.
I had the exact same understanding you did until I started reading more.


That's what kinda confused me... if it's a 20w, that means it was tested at cold. If it was just a 20 (no w), that means it was tested at 100c.

I thought at operating temp the oil viscosity was 30 using a 5w-30 oil. Having a viscosity of 30 will have more of a resistence to flow, ie thicker. So that being said it safe to say...as the oil gets hotter it gets thicker.

Although I'm probably using the word "thicker" incorrectly which is why you mentioned this. So I'd probably be more correct to say. As the oil its hotter it will have more resistence to flow. Hmm...maybe stickier, per the definatation of viscousness....

Its safe to say 5w is the viscosity with the motor off and cool. Unless you live on the moon since I dont think it gets 100c outside very often no matter where you live.

I added some "w"'s onto some previous post by accident...heheh my bad...

To make matters more confusing 0W30 doesn't mean that the oil is thinner than a 5W30. German Castrol 0W30 is actually thicker at 100C than most 30 weights on the market. The oil just has the ability to flow in colder temps than a 5 or 10W30.

Oil is tested at 100C for a hot engine temp., not an ambient air temp. :D (see the link). It's the SAE's temp rule for measurement of an oil weight. And remember, as with the N. American Syntec in the STi above, it may have started out as a 30 weight but sheared down to a 20 weight. That's actually been done in STi's and Forester XT's in under 2,000 miles. A guy on bobistheoilguy.com ran German Castrol for 10,000 miles in a Sequoia and it still remained in grade. :)

From the link above on viscosity:
"The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature, the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).

SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt."

Everyone should just spend $20 on an analysis then they would know exactly what works for them.

-Dennis

I thought at operating temp the oil viscosity was 30 using a 5w-30 oil. Having a viscosity of 30 will have more of a resistence to flow, ie thicker. So that being said it safe to say...as the oil gets hotter it gets thicker.

Although I'm probably using the word "thicker" incorrectly which is why you mentioned this. So I'd probably be more correct to say. As the oil its hotter it will have more resistence to flow. Hmm...maybe stickier, per the definatation of viscousness....

Its safe to say 5w is the viscosity with the motor off and cool. Unless you live on the moon since I dont think it gets 100c outside very often no matter where you live.

I added some "w"'s onto some previous post by accident...heheh my bad...

As oil gets hotter, the "resistance to flow" is less - thinner. I'm sure we've all heard, "Warm your engine up before you change your oil because it'll flow out easier." That is true.

The whole Xw-XX system is actually confusing. It's easier to talk in terms of absolute numbers (cST and cP), but that would just scare most people. I'm an engineer so it's all good for me :)

I'm not sure who started the system, but he/she could have called a 5w-30 a 100w-5 or a 3.14w-1000. They arbitrarily picked a set of numbers. Why did they choose the second number to be bigger than the first? I have no idea.
In any case, we're stuck with the system. So if you want to know an oil's viscosity, you have to go look it up in a table or calculate it using equations.

I made a post over at bitog (Bob is the oil guy) to clarify the whole "Thin Oil Myth".
Click here (http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=51;t=000945)
There's a graph that shows M1 5w-30 vs 10w-30. In the graph, viscosity obviously goes down (thinner) as temp increases.

In that link, you might notice that it is NOT safe to say an oil's viscosity is a 5w when your motor is cool. The 5w is only relavent at really cold temps (-30c)! The 5w actually doesn't tell you much about the oil's viscosity at most ambient temps (Like 0c - 30c).

As bluesubie mentioned, a 0w-30 oil like GC can actually be thicker than a 5w-30 or 10w-30 at CERTAIN temperatures.

Whew, that was a mouthful... explaining things on the internet is hard :p
And I think bluesubie is trying to say the same thing I am, just in a different way. ;)

Back to your main topic, I guess your 30 sheared down to a 20. Most oil's do this and I'm sure the Subie engineers know this. I wouldn't worry too much, but you can always try different oils.

Wow, nice job on bitog. That's enough info to make your head spin. :eek: It should be part of the Oil FAQ here. Did anyone ever figure out why Mobil thickened up the 5W30?

-Dennis

I didn't see any reasons why the Mobil1 5w-30 was thickened.
Maybe it helps the 30 weight stay in grade - more shear stable. That's just a guess.

Honestly, there's a LOT about oil I still don't understand. There's only so much you can learn from the internet...

Yeah, FD777 great write-up on BITOG. I can't help but think "if it ain't broke, don't fix it" when I switched from M1 5W-30 to 10W-30 which led to some oil consumption. It was the "thin oil myth" that caused me to switch, and like a dumbass I fell into it without doing my homework!

My first oil analysis with 10W-30 showed the oil shearing out of grade like in the OP's case. It doesn't seem to be hurting anything though. My plan is to do some custom blends (sounds so scientific :lol:) to thicken up the oil a little more than the 5W-30 for good measure.

Can you post the entire oil analysis? Take a screenshot and use Imageshack or something to host it...

Just because the oil was in 20wt range doesn't mean much. Was it at the upper, middle or lower end of the range? It's pretty normal for a 30wt oil which starts out at the thin side of a 30wt to go to a high 20wt range after 2-5k miles before thickening back up.

drees, are you referring to me or the OP?

In my case, SUS viscosity was 56.8 (should be 59-68)! :eek:

Can you post the entire oil analysis? Take a screenshot and use Imageshack or something to host it...

Just because the oil was in 20wt range doesn't mean much. Was it at the upper, middle or lower end of the range? It's pretty normal for a 30wt oil which starts out at the thin side of a 30wt to go to a high 20wt range after 2-5k miles before thickening back up.
Sure, I will post the report tonight or early tomorrow morning. The PDF file is on my home computer. I'm not sure at what temp. the 20wt was reported. I think I will email them and ask.

I thought the thickening was a side effect of moving to the new SM spec (from SL)... I don't know for sure, though.

andy

I didn't see any reasons why the Mobil1 5w-30 was thickened.
Maybe it helps the 30 weight stay in grade - more shear stable. That's just a guess.

Honestly, there's a LOT about oil I still don't understand. There's only so much you can learn from the internet...

I thought the thickening was a side effect of moving to the new SM spec (from SL)... I don't know for sure, though.

andy
The thickening that he is referring to in the post that you quoted was a response to my comment about Mobil1 5W30. The 5W30 is now thicker at 100C than the 10W30.

I believe that the thickening that you are referring to, as well as drees above, is the thickening back up of an oil after it thins out.

-Dennis

http://i23.photobucket.com/albums/b357/kelw1a/C71269.jpg

Here is a copy of the actual report for those interested. I also emailed the lab about the 20W comment. I will report back when I get an answer. I will run an analysis each time from now on. :banana:

As you can see, the viscosity is measured at 210F. A couple of causes of an oil shearing can be fuel dilution (short daily trips, esp. during winter) or wear-in metals. Both look normal and your engine is breaking in very nicely. After full break-in (20k or so), your silicon will drop if you're running an OEM air filter. Anyone else notice anything?

Over at bitog there's a doctor that runs 20 weights in his exotic cars. :) If you want to run a thicker oil for peace of mind, try German Castrol 0W30 or M1 5W40 Truck & SUV.

For comparison, below is my report on GC from last winter when my FXT had mileage close to your STi. My daily trips are 5 miles which is the reason for the fuel dilution (engine not completely warm). Look at that viscosity! :D

Edit: Made a mistake and this is a report with 21k miles on the car. Second column is GF-3 M1 5W30 with 13,524 on the car. Viscosity was 57.8 for that.

First column is current, second column is M1 5W30 w/5,774 miles on the oil.

Equipment make: Subaru
Equipment model: 2.5L Turbo
Oil use interval: 5,930 miles
Oil type & Grade: Castrol Syntec 0W30
Make-up oil added: 0
Miles on unit: 21,930
Air filter: Amsoil
Oil filter: OEM

Aluminum 4 6
Chromium 1 1
Iron 10 15
Copper 6 20
Lead 2 2
Tin 0 0
Molybdenum 12 63
Nickel 1 0
Maganese 0 0
Silver 0 0
Titanium 0 0
Potassium 0 3
Boron 14 115
Silicon 15 18
Sodium 2 6
Calcium 2582 3394
Magnesium 106 10
Phosphorous 680 764
Zinc 818 904
Barium 0 1

Properties
SUS Viscosity @ 210F: 64.8
Flashpoint: 365F (>385)
Fuel %: 1.0 (<2.0)
Antifreeze: 0 (0)
Water: 0 (<0.1)
Insolubules: .4 (<.6)

Dennis: Nice improvement. You can see your engine maturing in wear with this sample. Most metals have settled down, though iron and copper are still a little above average. They should drop more in the next sample. We did find a little bit of fuel dilution, which is common in engines that see a lot of city driving and/or idling. We don’t consider it a problem until it reads above 2.0%. No other contaminants present, and the viscosity was normal. The fuel isn’t hurting anything. Looks great!

As for the change in viscosity:

Yes, you've stated it correctly. We measure the hot side of the viscosity.
Although the viscosity was light, it was just barely into the 20W range. In
fact if I had written the report I probably would not have even mentioned
it, because it's borderline and it's not hurting anything. Heat and use will
cause a viscosity to shift like that, and as long as it does not get too
light or cause extra wear, it's really not a problem. There's a type of
diesel out there, the 6.0L Power Stroke, that routinely shears 15W/40 oil
into the 30W or sometimes even the 20W range, and it doesn't seem to hurt
anything. your viscosity is not shifting very much, so I would not worry
about it.

Hope this helps!

Kristin

This lab is awesome. Great analysis and great customer service. :cool:

conker, your analysis looks fine! Interesting that they have a different range for SUS vis readings for your oil, in my last reports the normal range is 55-62 for Mobil 1 5w30. For Amsoil 5w30 they listed 56-68 and for Mobil1 10w30 59-68.

If you search for threads I started on either here in the Service forum or on bitog in the UOA forum you can find my results.