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.
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Categories: 2010 GMC Terrain,DIY Maintenance