Oil burnin 5.3

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Grit dog

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So not a lot of experience with LS engines. Need some advice from the GMSB brain trust here…
01 Tahoe bought recently for our son’s commuter car.
Supposedly 120k miles (why I bought it, now 130k after the last few months of driving it), not sure I trust that the odometer hasn’t been swapped and same goes for the engine. No maintenance or repair history but a fairly believable story.
Mechanically it ran like a lower mile rig and honestly still does. However it does have a bit of an aire of previous owner idgaf. If that makes sense.
Typical cold start piston slap, no problem.
Little issue with it sputtering and sometimes dying right upon cold start. No persistent codes. Cleaned maf and double dose inj cleaner. Research says weepy intake manifold seal when cold. As it totally clears up after only a couple minutes tops of running.
Very small oil leak. Talking only a few drips overnight and not slinging oil underneath while driving. So the majority of the oil is not going on the ground but rather out the tailpipe.
BUT it’s an oil sucking pig. A quart per 1000miles maybe less. No blue smoke, haven’t pulled plugs but runs just like a sewing machine.
Put it this way, it never needs an oil change. Put 8-10k miles on it and probably 2 gal of oil or close to it by now.
What’s the skinny on these motors if they’re using oil?

Are they known for some simple (or expensive) issue if they’re using a lot of oil?
Sort of hinges on whether I keep it or make it someone else’s snackwagon in the near future.
Also any insight into the rough idle/dying after a cold start would be appreciated. I did one check for a vacuum leak real quick but cold wasn’t as cold that morning. I briefly thought I picked up a small intake manifold vac leak up front (spray starter fluid method) but not sure.
 
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bucket

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I'm not aware of any of them being oil burning pigs. Your description definitely sounds like it needs the intake gaskets though.
 

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I'm not aware of any of them being oil burning pigs. Your description definitely sounds like it needs the intake gaskets though.
the only gm powerplants it seems in the last 20 years that havent been an oil burner are the 3800 which sadly ended (but was of good design lineage from before so yay) and the LS/LT family of engines. almost seems like its by design but thats a LOT of new cars and engines sadly. Consumer reports agrees with me on that being unacceptable in the car industry but they keep doing it lol.
The 3.5l v6 (the northstar derived one not the high value or whatever one) and the northstar had something of a love of valve stem seal leaks and crankcase leaks. but the northstars multi piece block probably meant more on that last one lol.
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89Suburban

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You can add a catch can to keep the oil out of the intake but it won't solve the loss of oil problem. If this was a newer model with the AFM crap it would not surprise me at all though.
 

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Some earlier ones had issues with pcv valve that would cause large oil consumption. There was an updated pcv valve used which is not available new gm any more, but copies are being made. Depends if it valve cover has a built in pcv valve or it if slides in like an older gen engines
 

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You probably have leaking intake gaskets as they are know for failing on the earlier engines. They changed the color on the replacements so easier to ID. It's not a hard job to do and I recommend doing the knock sensors/valley gasket at the same time.(might all be in the kit I believe) Mine would burn about a 1-2qts in-between oil changes. Yes try the updated PCV valve cover. While your at it I'D soak the pistons with marvel mystery oil or seafoam to help break up carbon on them and get into the rings. Of course new plugs. Basic maintenance. Otherwise the engine will be trouble free. After you do that then take it for a spin like your stole it to clear it all out.
 

AuroraGirl

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Some earlier ones had issues with pcv valve that would cause large oil consumption. There was an updated pcv valve used which is not available new gm any more, but copies are being made. Depends if it valve cover has a built in pcv valve or it if slides in like an older gen engines
the measured orifice which is a constant vacuum draw but they did a lot of smart person math to arrive at a suitable opening and design haha , right?
 

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Thanks for the suggestions. I’ll look into the pcv valve.
I’ve done the knock sensors before on another 5.3. Great suggestion to replace while the intake is off.
 

Rusty Nail

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Ya. They got that "updated valve cover" and I was thinking the cold start piston slap (yay vortex) is a oil filter housing /bypass spring thingy.
There was a TSB (a recall?), i'm pretty sure.
Hope this helps!
:waytogo:


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AuroraGirl

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Grit dog

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Yes the AFM motors have the tendency to consume the oil and it is worth it (to me) to do the delete. My two sons have Chevies with the 2.4 they both drive to college. Both are low mileage and use about 1 quart per 1500 miles.
I have a 2.4 at home I use for business trips. I doesn't burn a drop. All three get the same maintenance and driving styles.
Not a lot of folks are aware that 20% of an engine's friction is from the pistons. Engineers have played with the ring/cylinder tolerances in these late model motors as a method to squeeze a little more fuel mileage of out them. This comes at the risk of blow by and increased oil consumption.
 

TotalyHucked

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Easiest thing to check is if it's got the updated VC/PCV on it. If you take the intake off, look inside and see how sludged it is. If it's more than just a light coating everywhere, that may be your issue. Also, while they're off, check for any numbers/symbols on the heads. I don't think it'll apply to your truck (if it's the original engine) but around '03-05ish, the Castech heads with the snowflake (IIRC) emblem were prone to cracking, allowing oil into the combustion chambers. I had an '04 Yukon that used about the same amount of oil, the only difference was that every once in a blue moon, upon cold start it would smoke screen the neighbor's house away. Cleared up about 3min later. Smoked less and less them more I drove it but still used oil like a SOB.
 

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heres another one showing the orifice style valve mentioned before
Once again Aurora girl you’re right. Some of the engine didn’t have removable pavement valves, they were build into the valve cover. This is common issue for these style engines. There is a new design valve cover that eliminates oil burn issue, by the description and mileage I would say this would be the problem. I seen this more than once. The new part number from GM or from Dorman is the corrected part. The direct replacement is no longer available, because of the design problem. Oriellys Carrie’s Dorman! Easy fix. Hope this helps . Also tons of you tube vids on the replacing the left(drivers side valve cover.
 

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