NEED HELP high engine oil consumption

[yazan]

hi , i have high engine oil consuming , no overheating , "little" weak acceleration power noticed some times, i have white smoke with engine start up only if the oil is more than 2000 km life time , the oil is becoming dark after less than 500 km
coolant fluid looks ok , transmission also is ok

any advice please

 

[Redbeard]

How much oil consumption is high? How many quarts per 1000 miles. My 4.2 uses less than a quart in 7-10k miles. Is there any dripping on the ground that you can see? In case you are throwing oil instead of burning it up. What kind of oil are you using? When I was using Mobile One synthetic I would throw about one drop out of the rear main seal per week. When I changed to Mobile One Extended that slight annoyance totally went away , but no smoking during any starts like you mention. Oil turning dark has no measure as to its ability to lubricate the engine, but the best way to check the quality of how well the oil is doing is send a sample to Blackstone for oil analysis. (https://www.blackstone-labs.com/). To learn a bit more about oil you may check out "Bob is the Oil guy" https://www.bobistheoilguy.com/ for good tips also.
edit: mileage around 185k miles on this 2004 4.2 engine

 

[Reprise]

Agree with everything @Redbeard mentioned above.

One last question - How many miles / km are on the motor? I see yours is listed as a 2002, so I'm guessing it may be a pretty high mileage vehicle.

You may want to consider having a compression test done on the cylinders. Based on your description, I'm guessing you may find a couple of valve seals worn or a stuck / worn piston ring.

If you're not already using an oil made for high mileage vehicles, you should give one a try. They're designed more to stop leaks (by swelling the seals), but some of the better ones have additives to help slow down consumption. But first, find out whether you're leaking it or burning it (or both.) Leaks are more easily corrected, of course.

 

[mrrsm]

Some Belated... But Technically Significant Observations about:

WHY Do High Mileage GM 4.2L Engines ...Consume SO Much Motor Oil:

(1) Excessive Carbon Deposits in the Combustion Chambers along with Gas-Gum literally allows for the *Gluing* of the Two Upper *Low Tension Compression Rings*, tightly sticking them (VERY firmly) inside of the Six Piston's Land and Grooves. THIS creates the freedom for an EXCESSIVE amount of Combustion Gases to BLOW-BY the Rings and Pressurize the Lower Engine Block above the Fluid Level of the Motor Oil.

(2) This Excess Blow-By creates enough Positive Pressure with the motion of each Stroke of the Pistons to act like an Air Pump that forces this Combustion By-Product Laden Gaseous Matter upwards and into the areas just above the Rotating Valve Train, right under the Sealed Valve Cover.

(3) The Presence of a PCV "Spigot" located at the very Front pf the Upper Valve Cover encourages the Pressurized Blow-By Exhaust in there to concentrate the *Spinning Cast-Off" droplets of oil directly onto the under side of the Valve Cover Chamber.

(4) Directly above all of this... is an Intake Vacuum that starts from the Air Filter Box moving through the Air Resonator and then into the Open Throttle Body. This activity forms a sufficient amount of SUCTION inside of the Small Rubber PCV Elbow Hose located in between the Upper Valve Cover and the Lower Front PCV Port in the Body of The Resonator.

(5) This SUCTION serves to DRAW OUT the Collecting Motor Oil, allowing it to get pulled out along with all of those Excessive, Pressurized Engine Blow-By Combustion Gas Fumes underneath there that will eventually allow the Heavier Old Motor Oil to Pool down inside of the bottom of the Resonator.

(6) Under Idle Conditions (a Period of STRONGEST Intake Vacuum) and later under Heavy Acceleration, enough of a Vacuum Force develops sufficient to Pull the Old Motor Oil Up and Into the Throttle Body and finally... it moves by Gravity and Vacuum downwards though each of the Intake Manifold Runners where it gets ingested along with the Air Stream and along with the Atomized Gasoline coming from the EFIs located just inside of each Intake Port Cylinder Opening. And FINALLY, that Old Motor Oil and Blow-By Gas gets incompletely burned along with that ingested Air and Sprayed-In Fuel.

(7) The over-burden of whatever does NOT get burned inside of each Cylinder eventually is pushed out during the Exhaust Strokes and will be broken down inside of the Catalytic Converter. This Extra Work involved is called "Poisoning The CAT" and THIS is a Major Cause of Ruining the CAT Performance, since heavy Hydro-Carbons have to be "Cracked" apart and broken down by the Very High Temperatures being created by ALL of this EXTRA *Stuff*.

(8) The Best Treatment for this particular problem is to perform a "Carbon Busting" Clean-Out of the Upper Combustion Chamber around the Valve Seats, the Piston Tops and the Two Top *Low Tension* Trapped Compression Rings using the ACDelco "Top Engine Cleaner" Treatment as the Method of Choice.

(9) The additional application of a "'Through-The-Gas-Tank" Treatment like Chevron Techron will help to augment the ACDelco TEC Treatment, but BOTH will be necessary for an effective effort at performance improvement in Compression, Power, Reduction in the Loss of Motor Oil and even... a bit of Improved Gas Mileage.

gmtnation acdelco tec at DuckDuckGo

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(10) The Real Proof that this is what is occurring in your Motor can be seen below... and if you likewise Discover any Old Motor Oil leaking out from around the Three Figure "8" Intake Manifold Gaskets that are failing to seal after too many miles of operation without being changed out... THIS is what is happening inside of the IM Runners as that Old Motor Oil gets Vacuumed down inside of those Runners. The Burned Carbon Gas-Gum Blow By Residues collect in what should otherwise be SPANKING CLEAN AND CLEAR INTAKE PORTS inside of the Aluminum Engine Head:



I hope this edifies and explains this Damned Mystery in a way that will make "Mechanical Common Sense" for us all. If it Helps... I've exported this Article into a PDF for inclusion in the FAQ ...with Moderator Approval. -- mrrsm--

A Related "On Topic" Thread:

'06 4.2L-Filthy oil inside air plenum.

I was cleaning the throttle body in my '06, and noticed that the inside of the air plenum (directly on top of the engine, just upstream of the throttle body), was sprayed with creamy looking oil. Apparently the short tube which supplies clean air to the top of the engine has instead been...

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