Ok. Finally hit 300K, Going with Quaker State Conventional(semi-Syn) 10w-40... $16 at walmart fpr 5 quarts...as an experiment to see how the next 1000 miles goes... So far, great oil pressure at Idle (40 psi) cold.....will report back..
OIl Grade Suggestion for 300k 6.0L Chevy..
- Thread starter RcClockman
- Start date
Well I can report that QS Conventional was NOT the way to go! Ate 1 1/2 qts in 700 mostly towing miles.. Full synthetic burn way less, but you guys already knew that!
When I switched a 98 cavalier to Quaker State for one change, consumption went up considerably. I believe I posted on here about it, probably 10 years ago. Didnt make sense..
Its uses a lot less when not towing... Im seeing 1/2 quart loss in 700 miles with no towing vs 2x as much towing....
Late to this, but consider a straight wt. SAE 30 or SAE 40. It will minimize consumption. You truck will love it!
(Look back on post #65.)
(Look back on post #65.)
It could also make it worse. If the rings are stuck/coked, a thicker dynamic oil film could allow more oil transport past the rings and thus increase consumption.
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Are you towing heavy loads like the OP? Also no two engines are alike.
So are you advocating a 0w-20 to "avoid more oil transport past the rings"?
In any case what you are saying is pure speculation, if that. Easy way for the OP to find out is give straight 30 or 40 a try. Stable oils make a lot of sense here.
The real thing going on here is that it’s time for an engine overhaul. It’s a 24 year old engine with 300,000 miles. Quite a run!
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dnewton3
Staff member
I think you need to step back and ask yourself WHY the engine is consuming oil.
I'm going to assume it's not massive external leaking of oil, or you would be on a different path. So the problem is likely that it's burning oil internally. There are a few routes where this can happen.
- poor PCV operation (this is a simple fix; one hopefully you've already addressed)
- poor valve stem sealing (could be from seal wear; could be from seal hardening or seal contamination)
- poor cylinder/ring fit (most likely from wear)
- poor piston/ring fit (most likely from coking/sludging of the ring pack which prohibits the rings from floating in the lands as they should)
- some combination of the above conditions
In these cases, using a thicker oil is only masking the issue.
If there is true mechanical wear, then you're only putting off the inevitable. And that's OK; just realize there is an impending point of doom somewhere down the line where no oil viscosity increase will reasonably take care of the issue(s).
If this is a matter of needing cleaning (to remove deposits which are prohibiting a good seal) or softening (to liberate a seal), then you might consider an oil with a very high cleaning ability. Yes, here I am going to recommend the HPL products. First a few OCIs with the HPL EC (engine cleaner) used with a decent group III oil, and frequent filter changes. Then their PCMO oils with their advanced esther/AN packages, again with a few frequent filter changes. While some may decry this approach due to cost, it's FAR cheaper than an engine rebuild or replacement. I'd recommend trying HPL rather than using ever-increasing viscosity changes.
I say this because I once had a very eye-opening experience regarding oil consumption and compression. I'll give you a quick summary rather than the long drawn-out story. My 1996 3.0L Taurus was consuming oil. It had been overheated by the previous owner when a freeze-plug popped and was driven home rather than immediately pulling over to cool down. The engine ran fine after the plug was replaced, but had some oil consumption and really poor compression on a few cylinders. I had resigned myself to just living with the problems. However, a long-departed member here (Gary Allan) tempted me to try a cleaning product (ARX) in a few cycles of a cleaning regime. After a few cycles of clean/rinse OCIs, the compression was fully restored and the oil consumption went away. The engine didn't need a rebuild; it desperately needed the rings liberated! The core problem was that the overheating had created such heat that when the car was driven home that evening, the rings were fully coked with burnt oil; just plain stuck in the lands. In the end, the "tri-ester" based cleaner did the job. It didn't happen overnight; it took a few OCis of cleaning and rinsing. But as God as my witness, it really did happen this way.
So perhaps consider using some HPL products, in the proper sequence, with correct application, and you may find that all your engine needs is a good, slow, methodical cleaning. It's far cheaper than the alternative of pulling an engine out ...
I'm going to assume it's not massive external leaking of oil, or you would be on a different path. So the problem is likely that it's burning oil internally. There are a few routes where this can happen.
- poor PCV operation (this is a simple fix; one hopefully you've already addressed)
- poor valve stem sealing (could be from seal wear; could be from seal hardening or seal contamination)
- poor cylinder/ring fit (most likely from wear)
- poor piston/ring fit (most likely from coking/sludging of the ring pack which prohibits the rings from floating in the lands as they should)
- some combination of the above conditions
In these cases, using a thicker oil is only masking the issue.
If there is true mechanical wear, then you're only putting off the inevitable. And that's OK; just realize there is an impending point of doom somewhere down the line where no oil viscosity increase will reasonably take care of the issue(s).
If this is a matter of needing cleaning (to remove deposits which are prohibiting a good seal) or softening (to liberate a seal), then you might consider an oil with a very high cleaning ability. Yes, here I am going to recommend the HPL products. First a few OCIs with the HPL EC (engine cleaner) used with a decent group III oil, and frequent filter changes. Then their PCMO oils with their advanced esther/AN packages, again with a few frequent filter changes. While some may decry this approach due to cost, it's FAR cheaper than an engine rebuild or replacement. I'd recommend trying HPL rather than using ever-increasing viscosity changes.
I say this because I once had a very eye-opening experience regarding oil consumption and compression. I'll give you a quick summary rather than the long drawn-out story. My 1996 3.0L Taurus was consuming oil. It had been overheated by the previous owner when a freeze-plug popped and was driven home rather than immediately pulling over to cool down. The engine ran fine after the plug was replaced, but had some oil consumption and really poor compression on a few cylinders. I had resigned myself to just living with the problems. However, a long-departed member here (Gary Allan) tempted me to try a cleaning product (ARX) in a few cycles of a cleaning regime. After a few cycles of clean/rinse OCIs, the compression was fully restored and the oil consumption went away. The engine didn't need a rebuild; it desperately needed the rings liberated! The core problem was that the overheating had created such heat that when the car was driven home that evening, the rings were fully coked with burnt oil; just plain stuck in the lands. In the end, the "tri-ester" based cleaner did the job. It didn't happen overnight; it took a few OCis of cleaning and rinsing. But as God as my witness, it really did happen this way.
So perhaps consider using some HPL products, in the proper sequence, with correct application, and you may find that all your engine needs is a good, slow, methodical cleaning. It's far cheaper than the alternative of pulling an engine out ...
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This has actually been observed in a couple of engines I've owned previous. I've also spoken with tribologists and lubricant engineers who have observed the same thing. There's a publication out there on it as well. We don't confidently know how this engine is consuming oil. An engine teardown would likely be needed to diagnose it. In which case, you repair it before reassembly. Otherwise, it's just trial and error. I'm just saying that a thicker base oil isn't always the solution to oil consumption.
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So it's that thicker oils will actually pass the rings easier? Interesting if true.
MolaKule
Staff member
Did the OP ever try HPL EC to clean the rings?
Maybe a new new set of valve stem seals would help.
Maybe a new new set of valve stem seals would help.
It's possible. The rings transition through all 3 lubrication regimes. They're in boundary lubrication at top dead center and bottom dead center, pass through mixed (elasto-hydrodynamic) lubrication up to ~20° crank rotation up to and away from TDC and BDC, and ride in hydrodynamic (full oil film) lubrication through the middle where piston speed is highest. The faster the piston speed, earlier the transition into hydrodynamic lubrication. The rings do not touch the cylinder wall in this regime, separated by an oil film that acts as the seal. Normally, the 2nd ring scrapes this oil film off with the oil ring regulating oil transport. If those rings are stuck, coked, or some other way weakened, they can allow too much oil between the rings and cylinder wall, which doesn't get scraped efficiently, leading to oil passing by to the chamber. In such a case, a thicker oil film could put more separation of the rings and walls, thus CAN allow more oil past them. It doesn't always work that way with variations in ring tension, cylinder bore, piston speed, etc... It's just one of those things you figure out by trail and error.
Using an oil high in polar ester, to clean up the polar organic deposits around the pistons and rings, can help improve ring seal. If this happens, you know it was stuck/coked rings. If it doesn't change it, the likely culprit is just worn out rings.
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Oils high in polar ester: Are we talking Group V?
I may have missed it, but OP, I know you were considering M-1 15w-50 , did you ever try it to reduce the consumption ?
I’ve had positive results using it in various classic 1960’s-1990’s classic cars that were using oil. The 15w-50 reduced consumption by 50%, more of a reduction on a few Ford FE big blocks.
Z
I’ve had positive results using it in various classic 1960’s-1990’s classic cars that were using oil. The 15w-50 reduced consumption by 50%, more of a reduction on a few Ford FE big blocks.
Z
Just Picked up 10 Qts.... Will Report back in a few months with results...
Try adding a bottle of Schaeffer EP Moly to the 10w40. It helped my 93 5.7l reduce consumption a lot.
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