03-03-09, 11:33 AM
MY 05 SRX (V6) is using about 1.5 quarts per 1000 miles so I took it to the dealer a few weeks ago. They needed to verify the oil use by changing the oil and letting me drive it 1000 miles and recheck the level. After the first test, it had used about 1.5 qts. He said alright, we have to do two tests for GM to cover any work. So we do it again and this time it used about the same. I called him to tell him I was bringing it in and he said they would probably end up putting new rings in it. When I get there to drop it off he told me that GM told him to do a "hard de-carbon" instead. Naturally I inquired about what exactly the process involved. He informed me that they take the spark plugs out and hook it up to a machine that injects a carbon eating chemical into the cylinders and cleans up the rings and "unsticks" them. I have never heard of this before and thought I would ask if anyone here had heard of it.
I never heard of that one. I wonder if it has any ill effects on the catalytic converter when you burn all the stuff off.
I recently found my 3.6 with 39K miles down a quart of oil with 65% left on the OLM. Oil usage is creeping up.
03-03-09, 12:48 PM
The car had 37k on it when I got it so I don't know when it started using oil. I checked it after owning it a short period and noticed it. The service guy said they had done this procedure to a couple others and it fixed the problem. I have my doubts though. I think it will improve it enough to get it out of the "excessive" oil use catagory so that they won't want to do any more work to it. I guess we will see soon.
03-03-09, 09:51 PM
Hard de-carbonize? I am assuming the valves guide seals are not worn and leaking oil and the car is not smoking indicating you need a valve job.
I would presume a mechanic will clean the PCV valve and check for excessive oil pressure first. Then he would remove the spark plugs, inspect them, attach a pressure gage to the spark plug holes, run an engine compression test and compare the test results. Then he/she would insert a borescope (a camera on the end of a flexible gooseneck) to see what is going on in the cylinders. If compression varies and the cylinder walls are scored, glazed or were never cross-hatched properly when originally honed, you will need a cylinder bore and new oversize pistons and rings. End of story. Sorry. Rebuilt, the engine will be good as new.
If none of this reveals anything, the bottom ring on the piston is the oil control ring and it may be broken by thermal stress from improper installation during assembly. Or it could be stuck. If stuck chemically, it may be unstuck. Its job is to "scrape" excess oil off the cylinder walls that would get by the other rings and hold a deliberate amount ready in a labyrinth to lubricate the pistons and rings. In theory, it can be "unstuck" if it has not already done damage to the groove in the piston that will keep it from "floating".
I recommend a steady diet of Techron in the gas and some Seafoam or Marvel Mystery oil in both the oil and gas. Techron is the only product I am aware of that really reduces deposits. The other additives are smaller, lighter oil molecules than motor oil. They get to go where the bigger oil molecules can't. Their lower boiling points and detergent properties dissolve varnish and boil the particulate residues out from all the moving parts where they are washed away by engine oil to the oil filter. Marvel Mystery oil also contained a compound that attacked tetraethyl lead deposits which formed when high-octane additives were used (back in precatalytic converter days--but not beneficial now). It is mainly kerosene. I don't know what is in Seafoam and have not had any experience with it.
If the cylinders are all good but the mechanic thinks the rings are still stuck, he will then try a de-carbonize treatment. Certain very nasty hydrocarbons can be injected into the cylinder and allowed to set, preferably for days. These chloride hydrocarbons will dissolve the carbon or varnish. He will then have to inject an oil back into the cylinder and let it set to lubricate the pistons for start-up. He turns the engine over with the plugs out to expel the extra fluid and lubricate the cylinder walls, inserts the plugs and fires the engine. If your lucky and the synthetic oil was used in this engine, the rings may go back to sealing and stop excess oil flow. If it does, I would recommend some Marvel Mystery Oil in the crankcase with every oil change, regular oil changes and that you confirm a synthetic oil is being used by whoever is changing your oil. Conventional oils today are great, unfortunately, they can also leave behind trace amounts of proteins and other residues. They don't call them fossil oils for nothing. Protein was in the animal before it was a fossil.
I am not a blind proponent of additives. Generally they are a waste of money and can do damage when used in significant amounts by diluting a blended oil's beneficial properties, such as anti-foaming. Modern oils are superior products with sophisticated properties.
03-03-09, 10:46 PM
Thanks for that excellent write up. I'm at 60K using 1 quart every 1500 miles. I'll try some of your advice.
When you say a "steady diet" of Techron, how often do you mean ?
03-10-09, 11:21 AM
the "decarb" procedure they recommend first is a four part top engine cleaning...to eliminate carbon build up and sticky rings in the top engine allowing oil to bypass and burn. this was being done before the bulletin came out to replace the rings. right now if you have failed the oil consumption test ( the specs are anything over one qt in 2000 miles is considered high) then the piston rings and valve guide seals should be replaced
I'm trying to avoid the carbon buildup problem by using only top tier gas bought from a full service Shell station with cute girls that pump your gas.
03-10-09, 02:00 PM
I brought my 2004 SRX V6 (85K) in for excessive consumption (1q every 1500).
Dealer stated it need to be more than 1qt every 1000 miles.
Service manager stated they have yet to replace any engines unless there was a rod knock.
Service manager stated they were able to void any claims by stating owners manual states to check oil at every fill up, If the owner does not check oil they are negligent.
I am also getting a oily/milky mixture from the valve cover breather hose that runs into the air intake, down under the MAF and into the air filter, which the dealer claims is condensation (3-6 oz per year).
03-10-09, 03:15 PM
verbatum under gm guidlines for oil consumption..1qt in 2000 miles. we have not had alot of these engine replaced but we have done many ring and guide seals with very good results. the milky stuff you see is normal, condensation mixed with a little oil. if you are using a qt in a 1000 miles you have a problem. have that service manager show you in writing his specs
03-18-09, 12:29 AM
derrickc, did they do the carbon cleaning ? What was the result ? Thanks.