The Guru's oil consumption writeup up close

[BodybyFisher]

I will describe this in detail in the future but I will say this.

1. synthethic while unnecessary in most cases based on daily driving definately has benefits. I am not dumping on synthetic at all. Nor am I saying that synthetic ITSELF causes or is responsible for increased wear or damage.

2. What I am saying is that synthetics superior flow that I have seen reported as 7 times better than dino oil is where the problem begins especially on an aging 93 to 99 NS. It is well documented that synthetics superior flow can and will drop oil pressure compared to the oil pressure developed via dino oil that does NOT flow as well which naturally equates to higher oil pressure. I have a case study where the oil pressure dropped 10 psi throughout the range with synthetic.

Here is a basic thought question IF the lifter cleararance developed using dino oil of .001 to .003 provides adequate upper engine oil pressure, .......now put your thinking cap on.... it would stand to reason that using synthetic that flows 7 TIMES BETTER at the same .001 to .003 clearance would DROP the upper engine oil pressure at a given RPM (and for that matter overall engine oil pressure). That THOUGHT is irrefutable GIVEN SYNTHETIC'S MUCH SUPERIOR FLOW CHARACTERISTIC.

Where it becomes a serious problem is at idle where the lower engine has enough pressure to keep the light off but the top of the engine where there is NO oil pressure sensor to set off a warning is getting less oil pressure, this is magnified as the engine ages.

Now this may not show itself in the lower part of the engine as badly as the upper part of the engine. Keep in mind that there are 32 leak points up there each of which flows oil 7 times better around them using synthetic. That would drop oil pressure in this location. This problem of decreased oil pressure would get worse as the lifter bore clearances all reached .003 and beyond and "leaked worse".

I am in the process of developing a test to prove this and will provide full documentation of my results, I think the results will be shocking. Facts and figufes are stronger support than opinions and rhetoric. It will take me some time to put this together but I plan to put 7 oil pressure gauges on the engine at various tap points and we will end this discussion one way or another for good with facts. Stay tuned

[winterset]

I ran my '96 on synthetic from new till last year. For many years, I had the oil pressure flicker / "STOP ENGINE" message, and after adding motor honey, it went away. I stopped synthetic 2 or so years ago because i only drove a few hundred miles a year, and i changed it out yearly. I do not believe synthetic caused any internal issues, but of course i dont know what is going on inside the head/block. The engine purs like new, and performs great. I have only 115000 mi on it.

I had a wet block from seepage using synthetic, and oil consumption was always on the higher side. I have conventional in it now, and the garage floor is staying dry, and i did not add motor honey on my last oil change 2 months ago, and i still do not see the flickering oil pressure light. When i look into my valve cover thru the cap with a light, it all looks clean and well lubricated. I am anxious on the tear down report by BBF.

The formulations of conventional oil has improved so much since synthetics first came out. I remember the commercials about "thermal breakdown" on a high performance engine. I do not believe they would be able to run that commercial today without a class action lawsuit.

Imo, synthetic has much greater benefits in cold climate starts or for someone running their car mostly at high speeds (80+) which for most is not in the USA.

[Terje Treff]

I will describe this in detail in the future but I will say this.

1. synthethic while unnecessary in most cases based on daily driving definately has benefits. I am not dumping on synthetic at all. Nor am I saying that synthetic ITSELF causes or is responsible for increased wear or damage.

2. What I am saying is that synthetics superior flow that I have seen reported as 7 times better than dino oil is where the problem begins especially on an aging 93 to 99 NS. It is well documented that synthetics superior flow can and will drop oil pressure compared to the oil pressure developed via dino oil that does NOT flow as well which naturally equates to higher oil pressure. I have a case study where the oil pressure dropped 10 psi throughout the range with synthetic.

Here is a basic thought question IF the lifter cleararance developed using dino oil of .001 to .003 provides adequate upper engine oil pressure, .......now put your thinking cap on.... it would stand to reason that using synthetic that flows 7 TIMES BETTER at the same .001 to .003 clearance would DROP the upper engine oil pressure at a given RPM (and for that matter overall engine oil pressure). That THOUGHT is irrefutable GIVEN SYNTHETIC'S MUCH SUPERIOR FLOW CHARACTERISTIC.

Where it becomes a serious problem is at idle where the lower engine has enough pressure to keep the light off but the top of the engine where there is NO oil pressure sensor to set off a warning is getting less oil pressure, this is magnified as the engine ages.

Now this may not show itself in the lower part of the engine as badly as the upper part of the engine. Keep in mind that there are 32 leak points up there each of which flows oil 7 times better around them using synthetic. That would drop oil pressure in this location. This problem of decreased oil pressure would get worse as the lifter bore clearances all reached .003 and beyond and "leaked worse".

I am in the process of developing a test to prove this and will provide full documentation of my results, I think the results will be shocking. Facts and figufes are stronger support than opinions and rhetoric. It will take me some time to put this together but I plan to put 7 oil pressure gauges on the engine at various tap points and we will end this discussion one way or another for good with facts. Stay tuned

This is very interesting and I like the scientific approach. I really look forward to seeing more on this.

[BodybyFisher]

Ill do my best

[Cadillac Jim]

The owner's manual and the FSM's all recommend 10W-30 for temperatures over 0 F (-18 C), with 5W-30 OK for temperatures no higher than 60 F ( 16 C) [1997 FSM pages 0B-1 an OB-2]. Synthetic oil IS NOT MENTIONED. And, the FSM warns sternly against oils that have higher numbers with 5W-40 as an example of a grade that it says never to use. Stick with this and the recommended change intervals with good quality oil and you are good.

When my 1997 ETC was new, the dealer recommended 5W-30 Mobil 1 as a "premium fill." This is not an opinion, I am simply reporting an experience.

I used 5W-30 Mobil 1 throughout the time I owned the ETC, which was about 15 years.

Synthetic oil is required for some GM and other high-performance engines such as Corvettes and the V-Series engines, Camaro ZL-1 etc. But there is no requirement re even recommendation for synthetic oil for other engines. GM recommends a blend of premium dino and synthetic oil, dexos 1®, that it uses on all cars in warranty other than those that require Mobil 1.

I use synthetic oil in my wife's car because she drives it very little and goes over a year between oil changes, and synthetic doesn't accumulate moisture/sludge as much as dino oil. Her car does not have a sludge or dirty oil problem. I have not tried the newer dino oils, which have improved along with everything else.

[Terje Treff]

On November 30, 2015 at 9:25 AM, Terje Treff said:

 

Thanks Kevin, good clarification,it doesnt require synthetic.

I believe the 93 through 99 can be harmed by synthetic after 2 years of research. I will have empirical data that will either prove or disprove my opinion and that harm has nothing to do with zddp or accelerated wear.

I am not an engineer or mechanic, but I have worked as a service advisor for several years. In my country, Norway, like most european countries, we use synthetic on everything, old or new. Never heard of damage due to synthetic oil. Generally non-synthetic isn`t even available at shops. I would be very surprised if your findings indicate damage due to the use of synthetic oil. I would go so far as to say if your research does indicate damage as a result of synthetic oil, the experiment is flawed (issues listed below notwithstanding).

 

I know some engines are not "engineered" for synthetic oil.

I know some older engines can develop leaks with synthetic.

I know some older engines can even experience internal damage due to synthetic oil loosening deposits.

 

However, these issues are not indicators that synthetic oil is harmful to certain engines, in my opinion. They are issues that arise from circumstantial factors.

 

I`m not trying to re-open an argument that I am sure has been hashed out many times here and other similar boards. I only have one point: synthetic is used on everything in Europe, old or new, and I have never heard of any cases of engine damage as a result. This is a discussion I ever only seen in the USA. There cannot be any doubt that synthetic oil is generally better than "dino" oil ?

 

....I would even claim that if these engines were run with synthetic from the start, they would not experience stuck oil rings nearly as often.

Forgot to update you all on this. Found that the PCV valve was missing (!!!). Put in a new one from Autozone ($2,99) and it was perfect immediately. Not a whiff of smoke left. 

[Bruce Nunnally]

Thanks for the update.  It helps to find out how things sorted out.

[Cowpie]

I picked up a 2006 CTS 3.6L several weeks back.  Had 52,000 miles and looked like it came off the showroom floor.  But oil consumption noticed right away.  I cleaned the MAF and TB, changed air filter, did engine flush and changed oil and filter, did a top side cleanup using CRC Intake Valve Cleaner, did the PCV mod by increasing lower port holes to 5/64 and top one to 7/64, and installed a Elite Engineering E2 PCV catch can.  The catch can has captured about 1-1.5 oz of oil every 100 miles.  Now I know where most of the oil is going.  But still using a little more than is being captured, so will do a change out this weekend and follow the lead of some folks outside the U.S. who are using a 0w40 or 5w40 in these engines.  I am going to use a Euro spec 5w40 synthetic this go around instead of a 5w30 synthetic.

 

There is no "requirement" to use Mobil 1.  U.S. Federal law states that if something is required, then the OEM must provide it to the consumer free.  So one can use any synthetic or synthetic blend they choose and still stay within warranty as long as it meets the spec required for their engine. For the newer stuff, that would be dexos1.

[Bruce Nunnally]

 I will be interested in your findings. I love fact based studies.

[JohnnyG]

"...But still using a little more than is being captured, so will do a change out this weekend and follow the lead of some folks outside the U.S. who are using a 0w40 or 5w40 in these engines.  I am going to use a Euro spec 5w40 synthetic this go around instead of a 5w30 synthetic."

The 0W-40 that you mention here should work well for you and should increase oil pressure slightly if that is your concern. The Euro-Spec is an interesting specification required by Mercedes Benz to meet fuel economy ratings in the W212 engines (V6, non turbo) and meets MB standard 229.5. ( look that up if you feel like a challenge!) Not many oils can be found in the US that meet that spec, including Valvoline Full Synthetic 5W-40. Yhe only issue that I see is that you are careful NOT to choose a diesel spec oil. Not that it will harm your engine, but you may lose in the MPG department.

Another good choice is Castrol 0W-30, (Synthetic, AKA "Green Castrol") which has a viscosity of near SAE 40 when hot. Don't forget the SAE 40 will still be thin when hot, just not as thin as SAE 30.

[Cadillac Jim]

There is a TSB on the HFV6 about oil consumption, #PIP4439A: HFV6 Oil Consumption - (Jun 20, 2011).  Apparently it applies to new cars in warranty that exhibit excessive oil consumption, e.g. more than a quart every 2000 miles.  The principal content of this TSB is

Quote

Verify the oil consumption concern following bulletin 01-06-01-011D.

In addition, check the engine air filter and replace the air filter element as necessary. Care must be taken to ensure that the air filter and air filter box are reassembled correctly so that the filter and air box seal and prevent foreign particles from bypassing the filter. Check for signs of foreign particles bypassing the filter and getting into the engine, such as dust or dirt in the air intake duct or on the throttle body. If dust or dirt is found, look for the source of the leak, such as incorrectly assembled air filter/air filter box, loose clamps or incorrectly assembled joints at the air duct, leaking sensor gaskets, damaged duct parts, etc. and correct as necessary.

If oil consumption is in excess of the guidelines in bulletin 01-06-01-011D, replace the piston rings and valve seals.

Other things I turned up are bad, missing, or incorrect oil drain plug, bad oil baffle in the valve/cam cover with the PCV (there was a TCB on this, #PIP4492Z: Oil Consumption And/Or Exhaust Smoke Due To Oil In The PCV System - (Jul 19, 2011), but this TCB seemed to apply only to V8 engines).

I would be very careful not to stress the engine when hot while you have 40-weight oil in it.

[Terje Treff]

On ‎24‎.‎11‎.‎2015 at 9:51 AM, Terje Treff said:

1. My 99`STS has enormous oil consumption! At least a quart pr. 100 miles (!) I have only seen oil sweat in the engine bay, and no drip anywhere.
2. It seems to "collect" oil and blow it out occasionally. Either at close to WOT, but also at moderate throttle if I have been stuck in traffic for a while. When it blows it out the smoke cloud can be enormous and quite embarrasing. The color is bluish.
3. I don`t generally see any smoke during driving, only on the occasions when it decides to blow it out in huge plumes.
4. The engine runs GREAT! Strong, smooth, powerful! Only occasional misfire with a short squeak sound that I assume is because of oil in the cylinders.
5. I recently bought the car so I don`t know the service history or what type of oil used. I have been topping off with 5W-30 dino oil for the time being. It has 137,000 miles.
6. I have tried repeated WOT applications many, many times. It made no difference so far.
7. If traffic allows, and I can drive generally "agressive", it appears to not collect as much oil to blow out. In other words it seems to "collect" oil in particular when driving calmly, either highway driving or stop and go traffic (i.e. the problem is the same if I go 70mph on highway or 5mph in traffic, as long as I don`t use heavy throttle). I have been staying in 3rd for long periods of time at 50-70mph and it doesn`t appear to make much difference (gas mileage suffers greatly though).
8. It also blows a huge plume when I start the engine after the car has been sitting - no matter how long, half our or 3 days.

I have read all the comments about this problem, but wanted to know if there is a particular place I should start, considering that the oil consumption is extreme. Am I wasting my time with WOT applications ? Should I use oil additives or fuel additives ? Or does this seem to be a severe enough problem that the only way to fix it is to replace piston rings ? How do I check the PVC valve? Where is it ? I have lots of experience working on cars (hobby) but this is an unkown car to me.

I would really appreciate any advice. The car is in beautiful condition inside and out with only minor other problems. I love it, but this is taking the fun out of it. I would be super happy filling a quart pr. 1000 miles....

I posted another place in the thread too, but wanted to update you all on this: The PCV valve was missing! There was just a rubber plug where the hose is supposed to connect to the PCV valve. I put in a $2.99 valve from Autozone and the problem disappeared immediately. No smoke. Oil consumption back to normal (I`ve only drive 900 miles since the fix so far without having to refill, but since it was a quart per 100 miles before I`m happy).

[BodybyFisher]

delete

[BodybyFisher]

16 minutes ago, Terje Treff said:

I posted another place in the thread too, but wanted to update you all on this: The PCV valve was missing! There was just a rubber plug where the hose is supposed to connect to the PCV valve. I put in a $2.99 valve from Autozone and the problem disappeared immediately. No smoke. Oil consumption back to normal (I`ve only drive 900 miles since the fix so far without having to refill, but since it was a quart per 100 miles before I`m happy).

Very interesting Terje, I wonder how that happened? 

Thank you for posting the fix on this.   What was plugged, the cam cover and the hose?   The PCV valve usually plugs into the cam cover and a hose is connected to it.  How was it set up?, were both places plugged?   Very strange.   Was this engine worked on that you were aware of?

[BodybyFisher]

For some reason, my post went behind, Terje's post, I don't understand why.  

[Terje Treff]

17 minutes ago, BodybyFisher said:

Very interesting Terje, I wonder how that happened? 

Thank you for posting the fix on this.   What was plugged, the cam cover and the hose?   The PCV valve usually plugs into the cam cover and a hose is connected to it.  How was it set up?, were both places plugged?   Very strange.   Was this engine worked on that you were aware of?

Hi, basically the rubber plug that was supposed to connect the hose to the top of the PCV valve was (seemingly) replaced with a rubber plug that just fit into the hole. It looked normal from the outside with the hose and connection, but as I realized now I should have been able to see the top of the PCV valve sticking out from the valve cover under the rubber plug - it was not.

I`m just not familiar with the past history of the car, and I`ve only had it for less than a year. Technically otherwise it`s in generally excellent condition technically and cosmetically (and recently passed VA Safety Inspection with no faults).

[BodybyFisher]

So the PCV was in place where it goes, and someone removed the hose and plugged it?

[Bruce Nunnally]

41 minutes ago, BodybyFisher said:

For some reason, my post went behind, Terje's post, I don't understand why.  

LIkely the time zone setting in profile for one of you is not correct?

[Terje Treff]

16 minutes ago, BodybyFisher said:

So the PCV was in place where it goes, and someone removed the hose and plugged it?

The PCV valve was just gone, and the rubber connector from the hose was replaced with one that just fit into the hole in the valve cover. I have no idea when and why. So the hose was there and connected so it looked more or less normal.

[Terje Treff]

4 minutes ago, Bruce Nunnally said:

LIkely the time zone setting in profile for one of you is not correct?

I might be in a different time zone because our internet service orignates overseas (foreign service).

[BodybyFisher]

Delete 

[BodybyFisher]

53 minutes ago, Terje Treff said:

The PCV valve was just gone, and the rubber connector from the hose was replaced with one that just fit into the hole in the valve cover. I have no idea when and why. So the hose was there and connected so it looked more or less normal.

Very interesting, I wonder how many others that are consuming oil have had this happen,

[rockfangd]

On one cam cover there is a pcv valve, in the other there is a hose with a tube at the end.

 I forget off hand which one gets the pcv valve. Believe it is the rear 

[winterset]

Can be that a previous owner was overfilling the oil and the pcv was sucking the blowby into the intake and gumming it all up.   They thought the correct thing to do was to plug up the pcv. BUT....... We all know to check the oil after shutting the hot engine off and waiting 5 minutes.  Also, stay on the lower edge of fill as in this case more is not better 7.0 is better than 8.0.  7.5 is best, but sometimes tough to get at for the unfamiliar.

[Cowpie]

Well, I didn't use a 40w in mine, but I did do an engine flush treatment over 2000 miles and moved to a 10w30 synthetic.   After the second engine flush and oil change, the oil consumption dropped quite a bit.  Instead of almost 1 qt per 1000 miles, down to 1/4 qt in 1000 miles.  The catch can captured roughly 5 oz of oil over 1000 miles now, and that leaves about 3 oz unaccounted for so figure the engine is "using" it.  3 oz actual engine use in 1000 miles is pretty tolerable for a engine with 55,000 miles on it that was poorly maintained for the first 52,000 miles.   The PCV port is poorly designed and needs some good baffling inside the valve cover to keep oil away from it during operation.  And part of the reason for it grabbing so much oil before in mine had to come from excessive blowby on the piston rings.  The two engine flushes could have gotten the rings freed up somewhat so things are sealing better and that slowed both the consumption and the PCV oil problem. No way to know for sure without a engine tear down.