DB, I understand chain stretch and that’s due to wear on each individual roller. A few thousandths on that one, a few on that one, and it adds up quickly. JMHO, but it still boils down to clean oil or not. The cut and paste partial from GM below tells me the interval was not only too long in the first place but the revised interval is also too long.
On certain 2007 model year GMC Acadia; Saturn OUTLOOK; 2007-2009 model year Cadillac CTS, SRX, STS; 2009 model year Buick Enclave; Chevrolet Traverse; GMC Acadia; and Saturn OUTLOOK vehicles equipped with a HFV6 engine, under certain driving conditions, and with extended oil change intervals, the timing chain could wear prematurely and cause the illumination of the Service Engine Soon light.
CORRECTION
Dealers are to reprogram the engine control module, including the engine oil life monitor.
A few measly thousandths of an inch wear on each roller, especially considering the length of some modern chains, can add up quickly. Factor in the sludge effect on chain tensioners which then allow the chain to slap a little and they may not last that long.
Some around here may remember the Traverse wiped engine incident on this forum a few years ago.
Sorry to see you’re still catching flak over nothing CSA. I’ve worked the service counter and been there, done that so I understand. Fully.
@ok4450 you found the BS GM TSB I was referring to.
But if you read my entire post, it has since been recognized that shortening the oil change interval did not entirely resolve the problem. A weak design can’t be overcome by shortening the oil change interval.
By the way, the LY7 engine uses 3 chains, as it’s a DOHC V6.
My mom had a 1998 C230 with 10K service intervals. It had a timing chain and we went the full distance between services, using fully synthetic Mobil 1, as per the manufacturer. That didn’t have a stretched chain. And it didn’t have any sludge.
My point is that some engines are strong and well designed and others are weak and poorly designed.
Not being familiar with the chain problems on this motor, I might ask exactly what the design flaw is? Chain metal metallurgy, tensioner material issues, oil feed issues to the tensioners, cams, etc? Just wondering as there has to be a reason.
The Ford Escape and Mazda Tribute are the same cars, the V6 has a chain. Seems like the Sorento has a chain starting in 2007,but don’t rely on this post, just look it up in the gates website.
