2010 GMC Terrain: Oil Sample Analysis Results

Just over a week ago, I took an oil sample from our 2010 GMC Terrain and sent it to Blackstone Labs in Fort Wayne, Indiana, for analysis. Our GMC's built-in oil life monitor was telling us that the oil could last something like 10,000 or 11,000 miles, so I pulled 3 ounces from the crankcase when the oil had 5,731 miles under its belt (and the engine had 15,000-odd miles) to see what the oil had to say for itself.

In short, Blackstone told us we should change the oil sooner rather than later -- within the next thousand miles. Not every time, mind you, but this time, at least.

I talked to Ryan Stark of Blackstone Labs to understand why they're telling us this. Those are my scribbled notes, not his.

First, a recap of the basics:

The last change was done by a dealer at 9,615 miles, 5,731 miles ago. This was also the first oil change, as we had followed the owners manual's advice and keyed off the Terrain's on-board oil life monitor for the interval.

We have no way of knowing exactly what sort of oil the dealer put in, but the oil filler cap says that 5w30 is the right stuff. They did affix a tag to the windshield reminding us to come in 3 months or 3,000 miles. This little upselling gem set me off and got me digging into the subject.

Here are the highlights of Blackstone's results:

The average oil change interval for this engine family is 5,195 miles. But that's not the suggested oil change interval, by Blackstone or by GMC. This is nothing more than the average oil mileage at which all other Ecotech 2.4 samples were sent in to Blackstone for analysis. It's a measure of owner behavior. We can breeze right past this and look at the results themselves.

Our Terrain's oil viscosity measures 5w20. It's impossible to tell if the dealer installed 5w20 or 5w30 initially, because Ryan said "it could have sheared down". He went on to say this doesn't matter too much, because the ideal viscosity range has more to do with the local outdoor start-up temperature. They don't see a strong correlation between engine wear rates and oil viscosity in their historical database.

Certain wear metals (they measure 20 different ones) were detected at higher levels than would be expected for the typical "broken-in" engine. Iron is as 47 ppm instead of 12; Molybdenum is at 178 ppm instead of 64; Silicon is at 18 ppm instead of 11; Copper is at 7 ppm instead of 3 ppm. Most of the others are close to the norm. But Ryan says this does not mean the engine is still breaking in -- he says that wear-in is over and done with in the first 100 to 1,000 miles of operation.

What Blackstone is instead saying is these break-in "residuals" float around in there and hide in nooks and crannies within the block and head, something the oil life monitor may not account for in all cases. Oil and filter changes are the best way to get the stuff out, and you want it out because it's potentially abrasive stuff. While every engine design behaves differently with regard to this tendency, Blackstone thinks it would have been better in this case if we had gone with 4,000 to 5,000-mile intervals for the first three oil changes before we started to follow the oil life monitor's recommendation.

TBN is the Total Base Number of the oil. Jim, Ryan's dad, reminded me you can't run a pH test on a non-aqueous solution such as hydrocarbons, so the TBN test is run instead to measure how "basic" the oil is. The Total Base Number is a rough measure of the active level of detergent dispersants in the oil, additives that are there to keep dirt and solids in suspension so they can be captured by the oil filter.

Our oil's TBN is 1.8, and the recommended minimum is 1.0. But Ryan wasn't too concerned about this because he likes to focus on the number right below it on the report, the Insolubles Percentage. Our IP is still quite good at 0.2 compared to a target of 0.6 or less. He says that this tells him the detergent and filter are still doing a good job, whatever the TBN happens to be. From an insolubles and filtration standpoint, 10,000 miles still isn't out of the question.

He says the TBN test is more applicable to diesels, and it's more of a legacy test that some customers want to see. Oil (and detergent) sales and marketing efforts of the past used to tout their product's TBN as a measure of superiority versus the competition. (Remember Grandma's "Basic H" all-purpose cleaner? - I didn't until just now). They still run the TBN test for those that request it, but it's not part of the standard Blackstone test protocol. The Insolubles Percentage test, however, is standard.

The bottom line:

Ryan says the level of wear-in residuals is not alarming for an Ecotec engine of this relatively young age, but they are higher than he'd like to see. Blackstone suggests that we change the oil to get the levels down sooner rather than later. That said, the oil life monitor has not led us down the garden path into serious trouble. Oil life monitors are fine, he says, but the break-in residual issue leads him to recommend a more traditional timetable of 4,000 to 5,000 miles for the first two or three oil changes.

It's likely that Blackstone's conservative position on this comes from their typical customer -- fleet managers and trucking companies. These folks don't just want 100,000 miles of engine life, they want 300,000 miles and up, if they can get it. But they also don't want to spend any more money on maintenance and downtime then they need to. Strategic maintenance with an eye toward ultra-long engine life is their goal.

What's GM's take on these results? We'll see what we can find out and let you know.

In the meantime, can you guess what comes next? That's right, a GMC Terrain DIY oil-change post. But this one is going to be a bit different from the others I've done in the long-term fleet. That's as much of a hint as you're going to get.

Dan Edmunds, Director of Vehicle Testing

Categories: 2010 GMC Terrain,DIY Maintenance

28 Comments

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half_ton says:

11:42 AM, 09/30/10

Dan, it's time for you to teach classes and share your knowledge of all things automotive with the rest of the world.

Seriously though, this was a very interesting post. I typically look for demo vehicles BEFORE new or used models cause I feel get the best of both worlds; a new vehicle (I'm the first to title it) already broken in with low mileage (4-5K) and a reduced price. Assuming an oid change had been completed before making the vehicle available for sale, I would do my first oil change at approx 10K and follow the onboard computer thereafter but after reading this I think I may alter this to an oil change at 10K and again at 15K before following the computer.

Thanks Dan!

Report ItReport It

boost4 says:

11:43 AM, 09/30/10

Going to suction the oil out from the top, possibly?

diondi says:

12:32 PM, 09/30/10

Did you ask Ryan and Jim whether they had an Uncle/Brother/Cousin/relative named Tony? :D

htr_hardtech says:

12:47 PM, 09/30/10

Happy that mine was done at 1.5k, 3k, 6k, 9k, 12k, 15k, 18k, 21k, 24k miles.

No I have not paid a dime for all the oil changes, have another 2 years to go. Over done maybe, but I want the car to last a long time, and I would bet its not hurting it. When it goes to Syn it will be at 6k miles max instead.

roadburner says:

12:55 PM, 09/30/10

I've posted one of these UOAs before, but they might make an interesting comparison here:
Here's an older UOA from the MS3:
http://www.carspace.com/roadburner/Albums/roadburner%27s%20Album/MS3UOA6.JPG/photo/v./photo.jpg
And one from the X3:
http://www.carspace.com/roadburner/Albums/roadburner%27s%20Album/X3UOA4.JPG/photo/v./photo.jpg
In short, Mazda's recommendation of 5,000 to 7,500 miles is acceptable(at least when using a Honda/Acura HTO-06 certified oil). On the other hand, BMW's OCI of 16,000-17,000 miles is extremely optimistic- even when using a BMW Longlife LL-01 oil.

liquoredonlife says:

01:23 PM, 09/30/10

Are there any cars in the fleet that specifically request 5W-20? I've heard that this isn't a good enough oil to run, and that it's typically only suggested by manufacturers to meet CAFE regulations. I'd be curious of the fuel economy differences of running 5W-30 vs 5W-20, as well as how well either protects.

konocar400h says:

01:57 PM, 09/30/10

@liquoredonlife

My Hyundai Sonata V6 recommends 5w-20 as well, and I've heard that it can be noisy. I haven't heard anything about it affecting the longevity of the engine. If anyone has any more insight onto that I would like to know too

teampenske3 says:

02:07 PM, 09/30/10

Thank you AP Chemistry for helping me understand all that. So basically, both the dealer and the oil monitor are right. The dealer recommends the shorter interval for the reasons stated by Blackstone (to get rid of the excess metals), while the oil life monitor should be used as a guide after the first three changes. My question is, although this is specific to the GM engine, should a similar method be used for other new cars? Do they also need the first few changes to be at 4,000-5,000 mile intervals?

And Dan, I don't know if I mentioned this or not, but you are a scientific whiz. Care to help me with VSEPR Theory and Lewis structures?

bimmerjay says:

02:27 PM, 09/30/10

"The dealer recommends the shorter interval for the reasons stated by Blackstone (to get rid of the excess metals), while the oil life monitor should be used as a guide after the first three changes."

The dealer's recommendation is not based on any technically objective or modern scientific measure whatsoever. It is 100% based on their desire to maximize revenue on oil change services. 3 months/3k miles is an antiquated standard that many people still believe in despite a complete lack of rationality.

moparfool says:

02:50 PM, 09/30/10

Excellent post that helps me understand oil change requirements.

My Dodge Challenger with 5.7 liter engine recommends 5W -20 oil with a change interval of 6,000 miles or six months. I had the oil changed at 3K, 7K, 10K, and 13.8K by the dealer, who always puts a 3000 mile, three month oil change sticker on the windshield. I perceive no problem with engine noise - exhaust rumble would over ride engine noise anyway on this car.

The engine takes seven quarts of oil, so perhaps the extra two quarts over the "standard" five quart oil capacity helps dilute any contaminants that are floating around in the engine. And I am sure the 5W-20 requirement is mostly because of meeting mileage standards. I assume that the engine was designed to be OK with 5W-20 and that this oil provides the necessary lubrication even at the lighter weights.

Based on the above engine oil report, I plan to change oil about every 5K - 6K (or six months) from now on. The car has the lifetime drive train warranty and I want to make sure I keep it valid.

03:08 PM, 09/30/10

As stated in the article, I believe the reasons for higher viscosity oil is the propensity to sheer over time, temperature cycles, introduction of contaminants, etc. Several folks in the Mazdaspeed3 community are running 0w-40/5w-40 because over time it sheers down to 0/5w-30 and is also vital in maintaining the somewhat overworked stock turbo. Also, someone got word that the European manual is recommending 5w-40.

We also generally have minor/moderate issues with fuel dilution that have led people to install oil catch cans as well. The amount of gunk caught that would've been released through the intake manifold is a bit startling.

@konocar400h - I'd check the Sonata forums and see what people are using, perhaps what people overseas are using as well since I don't feel that engine oil choices are always in the very best interest of engine longevity. For what it's worth, Mazda dealerships are not recommending the use of synthetic oil for Mazdaspeed3's.

church123 says:

03:29 PM, 09/30/10

Does anyone know how GM does it's oil life monitoring? As I understand it, most manufacturers do it by looking at total engine loading, usually through the mass air flow sensor. I know Honda/Acura does theirs this way.

If cumulative MAF loads are the primary determinant, I think that you've got to take the in car recommendations with a grain of salt since they are developed using a model of expected oil life versus loading, rather than direct measurement.

If there is another method used (direct measurement of some oil property), I'd love to hear about it.

firstwagon says:

03:53 PM, 09/30/10

Betting a lot of people will still decide it's still all a scam to make more money for dealers and keep driving to 10,000 miles before changing it.

allthingshonda says:

04:22 PM, 09/30/10

I was informed that Honda/Acura uses GM's oil life monitoring system because their engineers decided this was currently the best on the market and it didn't make sense to spend money on R/D to come up with your own when you could just purchase the right to use it from GM. This explains why the max amount of miles allowed on GM and Honda products is 10,000-11,000 miles.

Also their oil life monitors look at more than the info from the MAF sensor. It also uses info from sensors that monitor ambient temperatures, engine running time, miles driven, number of cold starts etc. to determine oil life.

I think following the recommendations of the computer is safe. The manufacturers are not going to risk damage from infrequent oil changes causing engine failure to ruin their reputations. If anything the computer is probably programmed to be overly cautious (like fuel gauges and coolant temperature gauges). Oil life monitors are easier to trust than the no dipstick trust the computer German cars. As a matter of fact simply pulling out the dipstick looking at the oil and smelling it can tell the owner a lot about how the engine is doing.

desmolicious says:

05:16 PM, 09/30/10

How is this oil sampling test valid unless Blackstone also tests an unused sample of the same batch of oil and makes a comparison?

Isn't a control sample required to determine the mineral content in the oil before seeing what running it in the car for thousands of miles does to it?

Or did I miss this in the story?

05:35 PM, 09/30/10

Thanks for the info allthingshonda, do you have a link to that info (Honda purchasing GM's tech?).

As I'm sure you know, engine run time and miles driven are all accounted for in measuring cumulative mass air flow, as is ambient temperature (affects density of air). The cold start info would be useful of course for estimating moisture dilution. Oil temp would be really critical, but most Hondas don't have an oil temp sensor.

Unfortunately, even if your info is 100% accurate, it doesn't really change the assertion that the oil is being predicted by a model instead of actual measurement of oil properties.

kevm14 says:

06:06 PM, 09/30/10

I would bet there isn't a single OEM doing any kind of direct measurement on oil (other than, say, temperature) to gauge oil life.

oldno7 says:

07:11 PM, 09/30/10

Very interesting, even if some of it is over my head!

Keep these good pieces coming!

ms3fun says:

03:35 AM, 10/ 1/10

After reading what you wrote, I went and looked through some German Mazda3 MPS forums and at Mazda's Germany website.
It's true. Mazda revised it's recommendation for the MS3 from 5W-30 to 5W-40 in Europe. Some owners go even to a 0W-50 or 5W-50 oil, just to add some more safety cushion.

Some info: The HTHS (High Temperature, High Shear, measured at 150 Deg. Celsius) number is lowered in a 5-30 oil compared to a 40 or 50 oil. (Nothing to do with viscosity)
In a 5-30 it's >2.9 3.5 mPa

If you consider the high temperatures the oil is exposed to in a turbo, it's probably not a bad idea to go with a 40 oil to get the added safety, especially if you consider the minute decrease in fuel economy (1 - 3%)

05:35 AM, 10/ 1/10

audisport says:

08:49 AM, 10/ 1/10

I still hate that my Audi and most others suggest 10k miles before oil changes. Especially for a turbo engine.

I've done the past few at 7.5k miles. Dealer insists that it's AOK though and the oil life moniter never signals me to take it in any sooner.

travelingman79 says:

09:05 AM, 10/ 1/10

Not sure if it's still the case, but in the E46 generation, BMW's way of determining mileage to next service was via fuel consumption. I think it's somewhere around 2500L of fuel consumed between services. The rationale supposedly was that city/track driving is going to consume more fuel than lots of highway driving and is also somewhat indicative of pressures on the engine, oil, etc.

01:26 PM, 10/ 1/10

@travelingman79

That's even better than just mass air flow, I like it. Looking purely at mass airflow doesn't necessarily tell you the level of operation like fueling does. Burning 100 lbs of air at light throttle will consume 7 lbs of fuel. But burning them at full throttle might consume more like 8 lbs.

It would also better accomodate cold start issues, general operating temperatures, etc. In fact, it seems like such an obvious step onward from looking at mass air flow that I feel a bit dense for not thinking of it myself :).

Still an approximation of oil life, but a better one for sure.

jagat101 says:

03:42 PM, 10/ 1/10

Thanks to this site (and Blackstone Labs), I've been running my 2000 Passat with a sludge prone 1.8T "turbo turd" free for over 10+ yrs now....

http://www.bobistheoilguy.com/forums/ubbthreads.php

05:27 PM, 10/ 1/10

"Still an approximation of oil life, but a better one for sure."

The original SI system that BMW introduced in the early '80s took into account cold starts, fuel consumption, rpm, and engine temperature. A BMW engineer told me that it was later determined that tracking fuel consumption alone was just -f not more- accurate than the fomula that incorporated multiple factors.

jlflemmons says:

08:36 AM, 10/ 2/10

I strongly agree with the statement from Blackstone regarding ambient start up temps. In my locale, central Texas, you will very rarely be starting a car in sub-freezing temperatures, yet often during the summer will be starting your car in the pre-dawn hours where the temps are already in the 70's and 80's! Yeah, the summers are toasty, but we can play golf all winter. :-)

Jim

87bonnev says:

08:43 AM, 10/ 3/10

DISCLOSURE: I Am a GM suspension engineer

Nice article Dan. Loved the detail. How about more engineers writing for IL and less "journalists"? ;-)

Here's an article that gives a brief description of how the GM system works:

http://www.gm.com/corporate/responsibility/environment/maintenance/simplified_maintenance_qa_040104.jsp

As far Honda paying to use GM's system, this is far more common than those outside the auto industry may think.

latraffic says:

02:20 AM, 08/16/11

The MazdaSpeed3 is one heck of a powerful machine and YES many drivers are using Higher Viscosity Oil (e.g. 20/50 & 0/40) to deal with the excessive heat produced by the engine. The whole catch can idea is needed b/c DI engines cant clean their intake valves with gasoline like a normal EFI engine....except Lexus, they have 2 injectors. Audi, BMW, and Mazda have this dirty valve issue! Shocking yes?