The last time a dealer laid hands on our 2010 GMC Terrain, they put a sticker on the windshield reminding us to come in for our next change at 3,000 miles or 3 months. Wrong!
Modern cars and the modern oils they run don't need such frequent changes. And this very GMC Terrain has a built-in oil life monitor that tells the driver exactly when the next change is due, right on the dash. And the calculation it makes is based on driving style and conditions, not straight time or mileage. Our dealer's scare tactics are nothing more than attempt to get into our wallet.
At the same moment our Terrain's oil was 4,000 miles old -- 1,000 miles past the dealer's "recommendation" -- the Terrain's own on-board oil life monitor was telling us the oil still had 60% of its life left. In other words, a 10,000 mile oil-change interval was going to be cool.
Since then, the Terrain has been on some easygoing road trips. With 5,731 miles on the oil, the oil life monitor now says the oil has 48% of its life left. The projected oil life is up over 11,000 miles because of our recent light-duty use.
But does the oil life monitor really have things all figured out? Will this oil still have what it takes 5,000 miles from now?
I decided to pull a sample and send it to a laboratory for analysis. Blackstone Labs in Fort Wayne, Indiana will do it for between $25 and $35.
The standard $25 test tells you how your engine is doing, based on an analysis of the metal and "insolubles" in the sample. A worthwhile option is the $10 TBN or Total Base Number test. This is the test that measures properties related to oil life.
It's clear that we have time on our side. Before we change our Terrain's oil, we're going to send a sample in for a TBN test. Here's how we pulled the sample you see above.
The bottle on the right is the sample bottle. Well, not the sample bottle; it's the shipping bottle. The sample bottle is inside, like those Russian nesting dolls. This is what you get if you take Blackstone up on their offer for a Free Test Kit. We'll see more in a moment.
On the left is an oil extractor. You don't need this, but it sure helps. Blackstone will sell you one for $30, and with it you can withdraw the oil straight up the dipstick tube. The sample only amounts to 3 oz, so almost all of the oil remains in the engine. This is the way to go if you want to do TBN test mid-stream, like I'm doing here.
Without one of these, you instead take the oil out of your drain pan when you change your oil. That's messy, and the results won't have any bearing on how much longer the oil will last, because, well, you already drained it out. Classic moot point, that is. A TBN test will still help you decide how much longer to let your new oil stay in, though.
There's a lot of stuff inside the black mailing bottle: the 3 oz sample bottle, an absorbent pad in case it leaks, a zip-loc to further contain that, some paperwork for you to fill out about the oil, your engine and your car, the address where you want the results sent, and how you're going to pay for the test.
This is what you'll receive when you send in for the free test kit. Note that they'll send you the kit for free, but the analysis will still cost you $25 when you send the sample back.
Pull the dipstick out, slide the extractor's hose in all the way to the bottom, then pull it back up about a half-inch before you start.
The engine must be off, but it's best to begin within seconds of shutting it down. The oil needs to be warm and, more importantly, recently circulated so any particles are still in suspension. Don't wait any more than a few minutes. I did this at the gas station while the gas was going in. And I finished taking the oil sample before the gas tank was full, too.
With the sample bottle attached to the extractor, simply pull gently on the handle to vacuum out the oil. Go slow, don't overflow. The vacuum pump won't force oil back down the tube if you need to stroke the handle a second time.
It's best to fill it about this full. Blackstone needs a certain amount to run all of their tests. Also, a fuller bottle doesn't slosh about.
This matters because the post office might turn up their nose at the sound of sloshing liquid. Blackstone says it's legal to ship motor oil through the mail in small quantities for analysis. They say the black bottle with the secondary bottle inside meets the regulations. They provide downloadable documentation on their website to show your postal agent if they still refuse the package.
But the folks I've met ay my local post office don't seem to respond well to sloshing sounds, the black bottle or the letter. Near as I can tell, they seem to think the black bottle is the ONLY bottle, perhaps because they can't see the secondary packaging inside. I've found it easier to put the entire package (sample bottle wrapped in absorbent pad, stuffed into ziploc, stuffed into black bottle) into a small box or cardboard mailing tube to avoid misinterpretation.
Finally, the paperwork. This gets stuffed into the black bottle, too. Outside the ziploc is best, I think, to guard against the unlikely small leak.
Blackstone turned this around quickly when I did this to my minivan. I got the results in a couple of days.
I expect to know something about our GMC Terrain's oil later this week.
Dan Edmunds, Director of Vehicle Testing @ 15,346 miles
mcloffs says:
09:28 PM, 09/19/10
I've used Blackstone on my '02 Passat and have been very happy -- got my oil-change intervals to 12,500 miles, using synthetic oil. Haven't had any problems with the post office; I just put stamps on the container and leave it in my mailbox.
vt8919 says:
09:33 PM, 09/19/10
Looking forward to the results! I wonder how accurate the life monitor will be compared to the test results, or vice versa.
ed341 says:
03:52 AM, 09/20/10
To play the Devil's advocate for a second here... couldn't the oil change interval be based on the estimated life span of the oil filter and not the oil? Just a thought.
ptcdawg says:
06:19 AM, 09/20/10
The dealer is out of line, calling for an oil change before it needs it.
stress83 says:
07:07 AM, 09/20/10
@ed341:
Assuming you are referring to the dealers' recommended service interval, then No. It is simply based on a 50 year old recommendation that no longer applies to modern vehicles. We can thank this on 50 year old dealer tactics that have not changed.
As the oil analysis will show, the filter is still working properly if all tests are normal. The owners manual also recommends changing the oil and filter at the one year mark if the OLMS has not stated it's time to change the oil before that time period.
Even so, one could hypotheically just change the oil filter periodically for peace of mind. The GM Ecotech engines are a simple canister design from the top of the engine rather than the side or bottom as was once traditional.
yellowbal says:
07:30 AM, 09/20/10
What about cars without dipsticks? No mid-cycle testing possible?
actualsize says:
07:53 AM, 09/20/10
@yellowbal: Good point. Seems like you'd have no choice but to recover oil from your oil drain pan at an oil change, then use the lab results to determine the interval for the next one. On the other hand, I'm pretty sure those cars that lack dipsticks usually have "active" oil life monitors. We're trying the oil analysis here to see how the two compare.
acbayard says:
09:23 AM, 09/20/10
It'll make an interesting experiment to harvest some oil when the active oil monitors say 50% life remaining, and when it says time to change oil. Perhaps get a glimpse of how the monitors calculate the remaining life, and how much margin of error do they provide for drivers that don't heed the change oil now message.
htr_hardtech says:
09:26 AM, 09/20/10
I cant wait to get this done when the time comes. I dont know if I trust what the moniter says in my G8 Gt (10-15k miles) but I do know 3k miles is way short nearly 8 quarts of oil. That being said, dealer is changing this out at 3k intervals on the dealers dime. Funny how I got the car to the price I wanted and walked out. They start throwing things at ya. 5 mins later I have a no maintence car for 3 years, never have to wash it (life of the car, free car wash), and detailed every 6 months.
Yes im evil to sales people... Im on oil change number 8 in a few weeks, still have a year and a half to go. But when its my dime I will look forward to this.
danielvwrx says:
12:59 PM, 09/20/10
have been reading your comment , cant believe that this even exists so would it be so that when your oil life is over the manufacturers could void your warrent if not servifed properly.
Subaru Impreza Tuning
fuhteng says:
01:33 PM, 09/20/10
I am looking forward to getting my second report back. The first said the 8,000 I was at (for my G8) was too much, so this is at 6,000 miles. I think it was because the guys at Midas didn't get the oil at the right time in the oil change (I got it right in the middle of the oil draining out).
I am also waiting on my fiancee's 2001 130k Honda at 3200 miles to see how her oil is looking too.
IL, I hope you guys get advertising dollars for this stuff! Great advice.
bankerdanny says:
02:40 PM, 09/20/10
I'm right at the 3k/3mos mark (per the Goodyear Auto Service window sticker) in the 2004 Jetta 1.8T I bought last month. We don't drive much, so a 2 week delay would only add about 500 miles, I'm think the analysis would be an interesting way to check on the engine status before I get the oil changed.
firstwagon says:
03:32 PM, 09/20/10
Interesting but I would rather just spend the money on actually changing the oil instead of paying a lab so I can be lazy and stretch it a few more miles.
The oil may still have life in it's components but it also has more dirt then new oil.
Cheap insurance IMHO.
ocramidajzj says:
05:39 PM, 09/20/10
I got to agree with first wagon. Changing oil is easy and cheap insurance.
mcloffs says:
06:14 PM, 09/20/10
When you drive roughly 25,000 miles a year like I do, extending oil-change intervals becomes a lot more appealing. Especially when you're using $50 worth of oil and filter for every change (not to mention wrestling with the pain-in-the-rear belly pan). I was very happy to get a couple of lab runs done and change my oil twice instead of five times a year.
actualsize says:
07:44 PM, 09/20/10
You don't do this every time. That's not the point. Do it once to see how long the interval can be for your driving style, then maybe do it when the car is getting long in the tooth to see about the internal health of the engine. The metal content "fingerprint" of the sample can tell you a lot about wear rates, and they can see coolant leaks, blow-by, etc.