Sludge, Conventional oil, DI engines ?

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So- ive been seeing posts on forums- where folks say that running Conventional oil in newer engines can lead to sludge buildup. Example the DI 3.6 since thats what I have. They say these engines run hotter and Conventional will not hold up like a Synthetic will. I have a 2010 3.6 DI in my Traverse. Ive always used Valvoline Conventional 5W-30 at 5,000 mile intervals. My UOA have been very nice. (as posted on BITOG) Im now at 82,000. So im just curious about what you folks have to say about this and potential sludge buildup in my engine. What if I did a couple of 2500 to 3000 mile Oil change intervals using VWB to clean out any potential sludge?
 
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I doubt sludge buildup is a problem, but I'd be interested to see the buildup on your intake valves. A short OCI isn't going to do anything for that, I doubt it would do anything anyways.
 
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Sludge forms when an oil is run too long, additives get depleted and insolubles, acid, etc build up. Have you ever done a UOA? If you're concerned you could do a couple short intervals, but instead it might be better to take a look into (or under) the valve covers to see how it looks. I did a test run and UOA on VWB 5w30 at a 5000 mile interval several years ago, and it still had plenty of additive left and was in good shape. However it was about an 80% highway interval so that should be factored in.
 
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Do a couple of OCIs with PP if you are concerned about cleaning. PP has cleaned up every engine I have used it in over 30-40,000 miles with 5000 mile OCIs. Now I only use synthetics like QSUD or PP. Just too easy and the cost is minimal for the benefit.
 

rbarrios

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Originally Posted By: bepperb
I doubt sludge buildup is a problem, but I'd be interested to see the buildup on your intake valves.
I plan on changing the plugs at 100,000 and will look at valves
 
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Correct me if I'm wrong but I thought GM's requirement for the use of Dexos certified oil is so that people run a semi-synthetic oil as a minimum.???? Like Ford's requirement of at least a semi-synthetic. Any semi-synthetic should not have sludge problems on a 5000 mile OCI. The price difference is very small between conventional and a semi-synthetic.
 
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Sludge is not a problem if you drive highway often, the problem is if you only do city driving DI tends to dump a lot of fuel in the chamber and therefore into your oil. They design DI engine with large sump (2.5L V6 with a 6.6 quart sump) for a reason.
 
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Originally Posted By: rshaw125
Correct me if I'm wrong but I thought GM's requirement for the use of Dexos certified oil is so that people run a semi-synthetic oil as a minimum.???? Like Ford's requirement of at least a semi-synthetic. Any semi-synthetic should not have sludge problems on a 5000 mile OCI. The price difference is very small between conventional and a semi-synthetic.
Ford doesn't have a requirement for a semi-synthetic. There are numerous conventionals (MS 5000, PYB) that meet the ford spec for both 20 and 30 grade - even what's printed in the owners manuals of the newer GTDI engines.
 
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Originally Posted By: rshaw125
Correct me if I'm wrong but I thought GM's requirement for the use of Dexos certified oil is so that people run a semi-synthetic oil as a minimum.???? Like Ford's requirement of at least a semi-synthetic. Any semi-synthetic should not have sludge problems on a 5000 mile OCI. The price difference is very small between conventional and a semi-synthetic.
DEXOS-1 did not become an recommendation until 2011. Ford does not have a semi-synthetic requirement. If any modern engine has a sludge problem on 5,000 mile OCI's in daily driver conditions and use. Then no oil will save it from sludgeing up and there is a very disturbing design and or mechanical issues that need to be addressed. Everything else is just band aids.
 
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Originally Posted By: dave1251
Ford does not have a semi-synthetic requirement. If any modern engine has a sludge problem on 5,000 mile OCI's in daily driver conditions and use. Then no oil will save it from sludgeing up and there is a very disturbing design and or mechanical issues that need to be addressed. Everything else is just band aids.
Some clarity and perspective to be sure.
 
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Without oxidation, nitration and other critical measurements, the UOA doesn't really tell you what condition the conventional oil is.
 
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Originally Posted By: rbarrios
Originally Posted By: Kuato
Have you ever done a UOA?
here you go- VWB in my 2010 3.6 DI engine
Nice report...I would stay at 5000, TBN was just over 1 at 5000 on an earlier report.
 
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Why not use a C3 spec, mid saps in your DI if you're concerned about carbon build up. Dexos2 is based on C3 so should be easy to find state side
 
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