Cobalt sludges synthetic every 3000 miles

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1,413
Location
Wisconsin
I have owned this XFE since new delivering its consistent 40-50 mpg up through 110000 miles. At first I would change around 50% oil life with synthetic and the oil looked brand new but then I had to have a timing chain replaced just out of warranty 50/50 deal with Chevy After that it started destroying oil, depending on the oil it gets noisy (metallic timing chain noise) at about 1500 miles and the stuff is black and spent by 3000 sludging my oil filter. (Doesn't seem to matter synthetic or Dino tried a few 40 wt oils but they don't seem to extend the fill just make the car sound better initially) I do find adding a small amount of heavier synthetic 40wt amsoil mid OCI quiets it down a while. I have just been changing the oil a lot to address. I got in on a lot of cheap AAP jugs of assorted pp 10w30 and 5w20 & 5w30 Mobil AP As a result I had leftovers since my decent cars use odd amounts of oil and decided since it's winter and the car does a lot of 5 mile winter trips now that I would just dump the leftovers in a 50/50 mix of Mobil ap 20/30 weights since its likely I have to change sooner than ap is rated for anyway. Car sounds normal and runs normal on this brew. I am curious though will I get better life with ap in the sump? (Never used AP or PP in this car) I would love to extend the fill but more or less have to change oil once it gets noisy and sludgy. Also Could I run PP 10w30 synthetic down to the -25F temps we usually experience or am I correct in keeping lighter oil in the winter? My hope would be 10w30 wouldn't crud up as quickly. The manual lists 10w30 as an acceptable substitute but lists no temperature range. I also have rotella t6 5w40 that I was going to run but I want to clear out the 2 leftover jugs of ap. (Less clutter) before I test it. Any ideas?
 

CT8

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15,392
Location
Idaho
What makes you think the AP is a better oil than any others you have used? It seems there is a problem.
 
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1,261
Location
PA
This has nothing to do with the oil. Something is wrong. It didn't sludge before, and now it does after the engine work.
 
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Messages
10,004
Location
Waco, TX
Originally Posted by umungus1122
This has nothing to do with the oil. Something is wrong....
100% .... find out if the fuel injectors are stuck open or something....
 
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11,404
Location
USA
Originally Posted by umungus1122
This has nothing to do with the oil. Something is wrong. It didn't sludge before, and now it does after the engine work.
approved
 
Messages
397
Location
Missouri
If it's producing "sludge" every 3k miles then you have something severely wrong, so wrong in fact I feel you'd have a ton of other issues such as the engine no longer producing sludge because it's dead
 
Messages
10,004
Location
Waco, TX
Originally Posted by BigShug681
...... a ton of other issues such as the engine no longer producing sludge because it's dead
Yeah, you need to stop driving it right now - find the problem before it's dead for good
 
Messages
2,031
Location
Minnesota
What do you mean by "it sludges". That's a pretty vague statement. Are you saying if you take the filter off it is all gummy inside at 3k miles? Perhaps milky. This is not an oil issue, there is something wrong that needs to be looked at NOW.
 
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Rmay635703

Thread starter
Messages
1,413
Location
Wisconsin
I checked the coolant level a couple weeks ago but I never have to add any. I will check it again by 3000 miles the oil looks super black like my 6.2 diesel but sticks to the filter and is much more gloppy than normal, I will have to photograph it in 3000 miles when I likely have to change oil. It's been doing this same thing for about 25,000 miles so if it were going to die it ought to be ready by now. Fuel economy and behavior/ power etc don't seem to be affected from new but after the chain was replaced I had to give it a little gas to take off in first, car was always torquey enough to ease into the clutch from an idle on flat ground (saves clutch wear) no I gotta give it a little fuel. Also I do always notice a little whip cream on the fill cap but I'm guessing that's condensation from short trips. I will have to trade cars with the other driver and try to diagnose, PCV is easy, maybe too much blow by? Ah well
 
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