Viscosity, wear, engine failure, oh my!

[Merkava_4]

Originally Posted By: drninja

Why is this a good trade-off to make? Can a 3.9 difference in cSt really
be the difference between the engine being properly lubricated or not?

Pennzoil Platinum
40C cSt - 57.5
100C cSt - 10.3

Shell RT6
40C cSt - 87
100C cSt - 14.2

Difference at 40C: 29.5 cSt
Difference at 100C: 3.9 cSt

If you use 15w40 Rotella T (as many say is fine in this car), the difference at 40C is 42.5 cSt.


That's a good question and so far nobody has answered it. I'm thinking maybe you asked
too many questions in one post. These guys can only handle one question at a time.

 

[JAG]

ACEA A/B oil categories are for gas and light diesel engines. The C category is for heavy duty diesel engines. A1/B1 and A5/B5 have HTHS viscosities less than 3.5 cP. A3/B3 and A3/B4 have viscosities >= 3.5 cP.

If you can't get Mobil 1 0W-40, Mobil 1 10w30 High Mileage is a decent choice in that engine in Texas climate and has a HTHS viscosity of 3.5 cP. I'd prefer 0W-40 though for viscometric and detergent additive reasons. Rotella 5W-40 T6 is another good choice.

 

[Skid]

Originally Posted By: OVERK1LL
You made the initial statement, so what is the logic behind it?


It was based on two things, my own long-ago experiences, which are no doubt worse than yours, and my recent observations that most WRX's of that vintage that I see in my neighborhood are not running all that well. High power density is a beeyotch.

Your mileage may vary. For all you know, I could be a bowling ball polisher.

 

[d00df00d]

Originally Posted By: Merkava_4
Originally Posted By: drninja

Why is this a good trade-off to make? Can a 3.9 difference in cSt really
be the difference between the engine being properly lubricated or not?

Pennzoil Platinum
40C cSt - 57.5
100C cSt - 10.3

Shell RT6
40C cSt - 87
100C cSt - 14.2

Difference at 40C: 29.5 cSt
Difference at 100C: 3.9 cSt

If you use 15w40 Rotella T (as many say is fine in this car), the difference at 40C is 42.5 cSt.


That's a good question and so far nobody has answered it. I'm thinking maybe you asked
too many questions in one post. These guys can only handle one question at a time.

Speak for yourself. There are several posts here that answer more than one question at a time, including addressing the question you highlighted.

Perhaps the answers weren't direct enough. I'm sure some people can only handle statements that are plainly spelled out.

I'll have another go. It's not that a few cSt here or there will make or break the engine's lubrication; hopefully we're not operating that close to the margins, or else we have other problems. It's that you want the oil to have the thinnest possible viscosity while retaining the appropriate characteristics. So, while 3.9 cSt probably won't "be the difference between the engine being properly lubricated or not," it's usually best to drop that 3.9 cSt as long as you're not critically sacrificing some other important feature (like HTHS or viscosity index) at the same time.

 

[bluesubie]

Old WRX? I only recently did my first engine mod on my 2004 FXT; Cobb AP Stage I running an OTS tune. It may be a coincidence, but the only problem that I've had was when I didn't run an oil with an HTHS of at least 3.5. I blew a turbo and my $25 used oil analysis really didn't give any indication of impending danger, except for a possibly unrelated minor uptick in lead to 10 ppm's.

Let's see what the owner's manual says. My guess is that it says 5w30 is preferred for the best fuel economy and that thicker viscosities are REQUIRED in high temps. There's also probably a chart that shows 10W-40 being allowed down to around -4 F.

Before I installed the AP, I did a 6k run on Mobil 1 0W-40. The wear was good but TBN had dropped to 1.9. My car is tough on oil. Like JAG recommended, I would go with Mobil 1 High Mileage (10W-30 or 10W-40) if you can't find Mobil 1 0W-40. Maybe the new SN version would hold TBN better, I don't know. I contacted XOM recently about which oil to use and they did recommend 0W-40 for my application.

-Dennis

 

[A_Harman]

Wow! You broke down Mobil 1 0w40 in 6000 miles!? Maybe the Mobil 1 High Mileage's would hold TBN better. They do have Mg detergents, instead of the all-Ca detergent of 0w40.

 

[CATERHAM]

I don't see the point of pushing the OCI in turbo applications.
Porsche halves the OCI on it's turbo models.

6,000 miles is a reasonably long OCI for a hard driven turbo.
Stick with the superior lubrication qualities of Mobil 1 0W-40 and change the oil when it's done.

 

[bluesubie]

Good point about the turbo OCI. After the turbo oil line screen clogging problems in 2.5's, SoA started recommending 3,750 mile OCI's in all turbos. I'm shocked they've gone with 7,500 miles in all turbos from MY 11. Subaru Canada still requires 3,750 mile OCI's on n/a cars and turbos, IIRC.

The OP does have a 2.0 and maybe they're not quite as hard on oil, although there have been 2.0's on nasioc with spun bearings. In one recent case the person ran Napa 5w30. No viscosity can fix the nut behind the wheel though.

My buddy with a 2002 WRX has been very lucky. He runs GC, never checks his oil between changes, runs 5-8k mile OCI's but never remembers exactly how many miles, has a turbo-back exhaust without engine management, and I'm the one that blows a turbo. When I told him how fast that I had gone once on a stretch of highway with no other cars around, he says that he does that on a daily basis. Oh and his car has been stolen twice with over a dozen additional attempts.

-Dennis

 

[OVERKILL]

Originally Posted By: Skid
Originally Posted By: OVERK1LL
You made the initial statement, so what is the logic behind it?


It was based on two things, my own long-ago experiences, which are no doubt worse than yours, and my recent observations that most WRX's of that vintage that I see in my neighborhood are not running all that well. High power density is a beeyotch.

Your mileage may vary. For all you know, I could be a bowling ball polisher.


Yes, but I imagine both things hinge on proper maintenance. I have no problem beating on an older car. But I maintain the heck out of them.

My point is I think that it has far more to do with how the vehicle has been maintained and treated then the number of years under its belt

 

[SteveSRT8]

The kids around here are hard on those little Subarus.

I know of one that blew up at only 20k miles. Many with blown engines and turbos failing.

They are a lot of fun but seem to fall apart quickly if modded, tuned, and driven aggressively.

 

[drninja]

Originally Posted By: bluesubie
My buddy with a 2002 WRX has been very lucky. He runs GC, never checks his oil between changes, runs 5-8k mile OCI's but never remembers exactly how many miles, has a turbo-back exhaust without engine management, and I'm the one that blows a turbo. When I told him how fast that I had gone once on a stretch of highway with no other cars around, he says that he does that on a daily basis. Oh and his car has been stolen twice with over a dozen additional attempts.

-Dennis


I wonder if there has ever been a catastrophic engine failure in one of these cars that could be conclusively shown to be caused by running a 5w30 "energy conserving" oil. Even your turbo failure could have been caused by any number of factors, including "[censored] happens". I also wonder if anyone has conclusively shown that an energy conserving oil shearing to a high 20-grade is actually detrimental to the health of the engine.

It shouldn't be surprising to anyone that has any knowledge of statistics that there will be a disproportionate # of spun bearings from people using 5w30, since that is what the manual recommends and is what MOST owners will use (this especially applies to the Mobil 1 hysteria since Mobil 1 is the best selling synthetic oil in the US). Also, people won't typically post on a forum to report that their car using 5w30 is running well. They will post when something breaks and they need to vent and ask for advice.

I'm not trying to say anyone is wrong for using either a 30-grade or a 40-grade oil. I really don't know. I'm just looking for some hard data, which I'm beginning to think does not exist. People can throw around speculation and anecdotal evidence all day, but it does not make a compelling argument.

Any thoughts?

 

[shpankey]

If you're going to mod up a turbo 4 cylinder & beat on it I would personally go with a high-end boutique oil like Red Line 5w30, Amsoil Dominator 10w30, Motul 300v 5w30 or Royal Purple XPR 5w30.

Red Line is my favorite as it made my turbo spool quicker. Lots of group V & gobs of Moly & a HTHS larger than some 40 weight oils but thinner at cold temps than most 30 weights, so you get the best of both worlds.

 

[d00df00d]

Originally Posted By: SteveSRT8
The kids around here are hard on those little Subarus.

I know of one that blew up at only 20k miles. Many with blown engines and turbos failing.

They are a lot of fun but seem to fall apart quickly if modded, tuned, and driven aggressively.

As in the discussion about oil, I'd blame the owners before the hardware for this. The cars are just fine; it's just that there are a lot of ways to mess them up, and too many owners take too lazy an approach to power adders.

 

[d00df00d]

Originally Posted By: drninja
I wonder if there has ever been a catastrophic engine failure in one of these cars that could be conclusively shown to be caused by running a 5w30 "energy conserving" oil. Even your turbo failure could have been caused by any number of factors, including "[censored] happens". I also wonder if anyone has conclusively shown that an energy conserving oil shearing to a high 20-grade is actually detrimental to the health of the engine.

It shouldn't be surprising to anyone that has any knowledge of statistics that there will be a disproportionate # of spun bearings from people using 5w30, since that is what the manual recommends and is what MOST owners will use (this especially applies to the Mobil 1 hysteria since Mobil 1 is the best selling synthetic oil in the US). Also, people won't typically post on a forum to report that their car using 5w30 is running well. They will post when something breaks and they need to vent and ask for advice.

I'm not trying to say anyone is wrong for using either a 30-grade or a 40-grade oil. I really don't know. I'm just looking for some hard data, which I'm beginning to think does not exist. People can throw around speculation and anecdotal evidence all day, but it does not make a compelling argument.

Any thoughts?

Absolutely dead-on.

 

[CATERHAM]

I agree.
On the street use the spec' oil.
If you track your car, install a oil pressure gauge. Then and only then consider running a heavier oil based on the actual oil pressure readings to restore the minimum optimum OP and nothing more.

 

[edhackett]

Actually, the Subaru manual does not recommend 5W30 for the use under which most people spun bearings. The manual(2003 WRX and 2008 LGT) clearly states that 5w30 is recommended for best fuel economy. For high temperatures and heavy duty use(that would include track days) they recommend thicker oils up to and including 10W-50 and 20W50. Nobody seems to actually RTFM and get past the required government CAFE brainwashing.

Ed

 

[drninja]

Originally Posted By: edhackett
Actually, the Subaru manual does not recommend 5W30 for the use under which most people spun bearings. The manual(2003 WRX and 2008 LGT) clearly states that 5w30 is recommended for best fuel economy. For high temperatures and heavy duty use(that would include track days) they recommend thicker oils up to and including 10W-50 and 20W50. Nobody seems to actually RTFM and get past the required government CAFE brainwashing.

Ed


Hi Ed,
Thanks for the reply. I agree that under the conditions most of these folks are spinning bearings, they should be using a higher grade oil than recommended. In your opinion, do you think a stock WRX driven under daily-driver conditions would require a thicker oil? Many on NASIOC seem to think so. I've read the manual and I have RT6 5w40 in my WRX right now since I live where it gets 100F+ for 3 months straight. I'm not immune to the hysteria either, and I've always wondered if I was doing the right thing.

 

[drninja]

BTW I didn't intend to make this thread specific to the WRX, but rather oil viscosities in general and how they interact in many different applications. Sorry it got so specific!

 

[45ACP]

Originally Posted By: drninja
Originally Posted By: edhackett
Actually, the Subaru manual does not recommend 5W30 for the use under which most people spun bearings. The manual(2003 WRX and 2008 LGT) clearly states that 5w30 is recommended for best fuel economy. For high temperatures and heavy duty use(that would include track days) they recommend thicker oils up to and including 10W-50 and 20W50. Nobody seems to actually RTFM and get past the required government CAFE brainwashing.

Ed


Hi Ed,
Thanks for the reply. I agree that under the conditions most of these folks are spinning bearings, they should be using a higher grade oil than recommended. In your opinion, do you think a stock WRX driven under daily-driver conditions would require a thicker oil? Many on NASIOC seem to think so. I've read the manual and I have RT6 5w40 in my WRX right now since I live where it gets 100F+ for 3 months straight. I'm not immune to the hysteria either, and I've always wondered if I was doing the right thing.

Many on NASIOC are RIGHT!

1. Just because SOME people use thin oil ALL THE TIME.. does not mean its right.. either all or part of the time...

2. You are wise to follow the advice of the carmaker since people tend to dismiss on while ANY car manual (RTFM, i like that) that specs heavier than a 30-weight oil as "Wrong." Yes. Wrong!

Therefore.. i believe you are doing the right thing with the oil you have chosen. But i just advocated a thick oil, so.. I may get pounded on. Or govt thugs or others sent out to get me.

Your caution with a 40-weight could very well be caution with a 50-weight but im not advocating that, just trying to get the whole 360 in here.. you said you dont track the car, and 40 should be fine.. you are doing nothing wrong though you COULD go thicker, but you already know enough to know that you dont need to go that thick unless you will be pushing that car.. Good! Other folks probably put the 15W and 20W 50 in there and thats ok too.

You are doing the right thing with your car's oil. IMHO.

STAND FIRM!

 

[bluesubie]

drninja - No unfortunately there isn't much data in regards to failures. And most people that do used oil analysis in turbo Subaru's on Resource/Energy Conserving oil are usually scared by their used oil analysis results and switch to something more robust. I didn't bother doing a used oil analysis when I had my turbo failure because it failed on a trip to SC and I used a lot of various make-up oil.

You say that you didn't want to steer this discussion as being specific to the WRX but it SHOULD be specific to the WRX. N/A Subaru's show great used oil analysis results on pretty much any oil at 8-10k mile intervals. Application, application, application.

Here's a recent used oil analysis on Pennzoil Ultra 10w30:
https://bobistheoilguy.com/forums/threads/2011-wrx-pennzoil-ultra-6-148-miles.165834/

Could the viscosity be too thin for the application?

-Dennis