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07.5 GMC Sierra loosing oil

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by bubba lee, May 25, 2013.

  1. bubba lee

    bubba lee New Member

    I need some help on this one. I just bought this truck used back in February and i have put about 6000 on the truck since then and have a totally of about 103K on the truck now. Its the 5.3 1500 z71. I got my oil changed about 3 weeks ago and the low oil warning came on and its the third time its done it. first time came on about a month ago around Easter and I just added oil to it to get it back to the level it should be at since I did not need an oil change quite yet, then like I said about 3 weeks ago it came on again and decided to go ahead and change my oil and see if that helped, I put Pennzoil high mileage in when I changed it. Well yesterday it came on once again. Each time it has come on the truck was about two quarts low (hardly any on the bottom of the dip stick). I have not a clue why it is doing this, my truck doesn't smoke or leak oil from the bottom? So how possibly is it getting low if I am not burning oil nor is it leaking out the bottom??? Thanks for the help guys.
  2. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Vehicles with catalytic converters can burn oil -use oil-without smoking
    because they literally burn the oil-completely-in the cat con-so NO SMOKE- despite oil getting past the rings
    or past the valve guide seals.
    In the "old days" it was common for cars to go smoking down the highway-now it is very uncommon-the cat con has to be cooked-DOA- for a car to smoke now
    and cars are much better build-so engines rarely wear so much that they use oil
    That being said-some 5.3's use oil
    Many folks suggest it is because of the AFM- automatic fuel management-meaning cylinder shutdown-
    which might contribute to oil use-because the cylinder walls will be "oiled" but the rings won't have much cal pressure to "seal them"-and it is also suggested that the closed intake causes more oil to be pulled past the valve guide seal.
    Other just suggest GM occasionally builds some engines that just weren't as well machined as they should have been-
    Who kno
    -point is some of them use too much oil
    If it was in warranty-GM would partially rebuild the upper end
    your best bet-make sure it isn't leaking-
    check to see just how much it uses
    and if it isn't horrible-horrible meaning 1 qt per 500 miles
    just add oil as needed.
    It would cost $1500 to rebuild-maybe more.
    If it runs ok-I would just add oil as needed
    Some folks dis engage the AFM- not sure how-chip maybe??
    This is a common problem.
    Might try 10w30 instead of 5w30??
    Do make sure it isn't a leak-get under it-bright light-look carefully-it can drip back
    And if you have AFM- find out how to prevent it from "coming on"
    I think 2007 was 1st year for AFM
    Luck
    Charlie
  3. j cat

    j cat Rockstar 3 Years 1000 Posts


    so is the oil used dexos GM approved engine oil. If not then this is one good reason this oil issue is occurring. I would check with the dealership using your VIN# to see if you have the AFM 5.3L engine. if this is a 2007 it is most likely AFM. also only use ac delco oil filters in these engines .
  4. GuyGene

    GuyGene Member

    This is a widespread issue with many 5.3 engines. A pinned (aka, sticky) thread about this oil usage problem is on another GM forum. Do a search, and it'll show up on the other forum. Tha thread has been going on for years. Not all 5.3s have the problem, but enough that it's a big problem for those who do.
  5. stchman

    stchman Active Member 1 Year 1000 Posts

    I assuming your 2007 Silverado is not the Classic (NBS), but the newer body style 2007-2013.

    If yes, then switch to an AC Delco filter and run Mobil 1 5W-30 oil. The AC Delco oil filter for your truck is a PF-48. The filter is at Walmart for ~$4.

    A good friend of mine owns an auto repair shop and has said that this helps out a great deal.
  6. GuyGene

    GuyGene Member

    I second the Delco filters. I actually try to use them in all my vehicles, but they can be hard to find. Stay away from Fram, most easily found!
  7. BlackBeaard

    BlackBeaard New Member

    GM has a technical service bullitin out about a problem such as yours, that engine has been known to burn oil when switching to the 4 cylinder mode, if you bring it to GM they will (i do not know about the cost) do an oil drop or burned test on it over a time span. after that they will start by dropping the oil pan and putting a diffrent fitting in the oil pan that i was told is called an umbrella. i dont know. any way i have had this problem with a few trucks in the family just like yours.
  8. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    When did you buy it and how many months/miles do you have on it since you bought it?
  9. nonnieselman

    nonnieselman Member 1 Year

    If you plan on keeping that truck for some time now a VVT delete kit is a good upgrade if you want to get rid of the V4 mode. Also installing a catch can for the PCV system will catch the oil vapors before goin in the intake and help keep everything inside clean.

    the VVT or DOD whatever they call it is horrible. good friend of mine just about makes a living fixing them. he will go in and do the delete and put another cam in it and with a tune he sends them on their way with no more problems.
  10. bubba lee

    bubba lee New Member

    I bought the truck back in February and have put about 8000 on the truck. Have any of yall heard of Royal Purple Oil? I have been doing a little bit of reading on it but don't know much. I think I may try putting the HPS series in 5w-30 in along with that AC Delco filter or maybe a Royal Purple filter? The truck already needs another oil change so im going to try changing to a different oil and filter first then if that doesn't work check out the PCV and AFM systems. Im trying my hardest to stay away from the dang Dealership, everytime I go there I spend to much money. Thanks again guys!!!

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