being di the fuel pressures are very high. It is possible for the secondary injection pump to leak fuel into the crankcase; as its mechanically driven off the engine....somewhat comparable to an old mechanical fuel pump. remember when the diaphrams on those leaked.

 

"Holey Buckets!!" -and I suppose it's not easy to check the pump itself for any signs of leaking,,,, -and I suppose the fuel rails pretty much "internal" as well,,, I just checked a brief description on the 3.6, and see they describe it as being driven off the exhaust cam. -and I see they list the pressures anywhere from about 500 psi to nearly 2000 depending on demand. WOW, I now can certainly see a potential for some bad problems,,,,bummer. Sure would have been nice it they would have kept that pump "external." -just saying,,,

Another thing that comes to my mind what an engineering challenge it must be to design high pressure seals for the rotating components. I was always impressed with how effective the seals are on diesel injections pumps, but at least diesel fuel is a lubricant. Whereas gasoline is purely a solvent!! Wow, I'd like to read an engineering paper on that type of seal,,, (I wonder if it is maybe a ceramic type,,,, hmmm,,, interesting.)

Oh yes, those old mechanical diaphragm fuel pumps,,, and that fabric reinforced rubber diaphragm would always eventually spring a leak. We were "lucky" with some of them, because they leaked externally. (creating a nice fire hazard of course) But the ones that leaked internally certainly ruined the motor oil !!

Tech2, Thanks for sharing.

 

Blackstone sent a kit for free and the test cost 25 bucks. my engine was spotless and they could detect the dirt and nickel particles from air and the oil... its INSANE.

 

Good to know. I just sent for my first kit. Thanks for posting.

 

quick note to tech2: -just noticed while reading about the LFX version of the 3.6 on the "gmauthority" website that one of the items listed is "new fuel pump and isolated fuel rail."

Which of course makes me suspect that these were updates directed toward reducing fuel dilution issues.

That "isolated fuel rail" part really sounds good to me, depending on what it means,,,

Your thoughts??

 

I work on a farm, and each tractor takes five to ten gallons of oil and two to three oil filters which gets really expessive. About a year ago we bought lubricheck that checks the oil and tells you when you need to change it. It also checks it for other things like antifreeze or fuel in your oil that can indicate if something is wrong it works great and is only $50. It has saved use so much money

 

Agreed. For any analysis, the TBN must be included in the testing. One thing that many overlook with the analysis game... it is not a test so much of what condition the engine is, as it is a test of the oil's condition. Based on the results, you can deduce something that might be a problem in the engine, but that is about it. It is an art form as much as it is a science. You get the wear numbers and such, but it isn't the numbers themselves that tell the story, it is the numbers in relation to each other. You could have an elevated copper level in a sample, but what is the source? Oil cooler? Cam bearings? Unless you understand the relationship to other wear metals, it can be hard to target what to look for.

And as acid increases in the engine from combustion, condensation, etc, the TBN is depleted accordingly. It is a general consensus that when TAN (Total Acid Number) and TBN meet a similar level, the oil is needing changed. Since doing a TAN along with a TBN starts becoming not cost effective for the average user, then TBN will do, but the general consensus there is that when TBN has reached 1/2 of the level it started out with, then the oil needs changed. You have to look at the tech sheets on the oil you are using to see the starting TBN level out of the bottle. If you don't keep acids under control, you can do some very serious harm to the internals of an engine. Elevated acid levels can cause elevated wear metals to appear. Nothing wrong with the motor, no component problems, yet, just that the oil can't handle the level of acid buildup. More frequent oil change is warranted, or maybe a oil brand change.

I have done hundreds of oil samples on various vehicles, primarily because of commercial uses of them. One wants to see changes in normal patterns and how they relate to various factors. You have to have detailed information to make an informed decision. A oil analysis without a TBN test is like swimming with one arm tied behind your back. Knowing what I have learned over the years regarding UOA's and how oils react under different operating conditions, I really do not use the Oil Life Monitor thing on the newer vehicles. It is good for the average user, but doesn't fit well within my own comfort level. I really want to know the condition of the oil, not one based on algorithmic variances in tables loaded on a ROM chip.

 

Excellent reports everyone!! (-see, there really is "intelligent life" out there after all !!,,,,)

Looking back to the title of the original question, is it worth it? It sure does depend on a lot of factors, most of which certainly should be decided on an individual basis. (-and in my opinion, "comfort level" is a totally valid reason.)

Just for my own "two cents worth" I will have to admit that it could be easily argued that I personally will very likely be "wasting my time and money" in doing so. And I say that for several reasons, among which are these: I will be using synthetic oil, and will be changing my oil and filter twice a year just like on every other vehicle I own. The total mileage between changes will be low. (At this point, I absolutely WILL NOT be doing service based on the oil life monitor.) -just me,,,, -just saying,,,

So now, how do I justify doing the oil analysis anyway? -well I could say, "just because I want to. So there!" (-and maybe that's the biggest factor,,,) However what can it hurt? -heck we all spend way more money on things much worse, I'd bet.

1. I am mostly just curious about it, and can always quit when it becomes too boring.
2. Maybe the fuel dilution issues on these DI engines will prove to be a serious problem.
3. I wonder what value, if any, such records would have if I should have the unlikely bad luck of actually having a serious internal engine failure? -just wondering,,,

Now for fleet owners, industrial applications, mining equipment, agricultural operations, and honestly probably every situation where "extended oil drain intervals" are justified, in this old guy's opinion a person would be foolish not to do them.

Does that make sense??
"Cheers Everyone !!"

 

Yep. Most folks outside of commercial users primarily do it for the comfort and information factor. And you are quite right, people will waste a ton of money on stuff that has less beneficial effect. Kinda like folks will spend thousands of dollars on lifts, rims and tires, plastidip, different grills and bumpers, LED lighting, air intakes, and other stuff yet will act like some corporate bean counting miser over an oil selection or doing an occasional analysis of it.

I run oil samples each time on my commercial stuff, and every once in a while on my private stuff. It is money well spent.

 

Just sharing a picture I took yesterday. I couldn't resist removing a couple of covers on my 3.6 LFX engine and snoop around. I was most curious about locating the fuel pump, and sure enough I think I found it!

It sure seems to me to be "external", and driven from the driver's side end of the front exhaust cam at a 90 degree angle. Thank goodness! Also, I couldn't get a good view of the fuel rails, but it does appear to me that they are also "external," apparently running along just under the plastic intake manifold and above the area that would have been the valley cover on the pushrod motors. -at any rate, I suspect it is all "external" to the crankcase, per se'.

So, here is hoping, that most all of the high pressure fuel is "external" on this LFX engine. The one area that I can see as being vulnerable is the seal on the pump drive end, which I suspect provides a pathway for leaks into the end of the cam cage, and of course into the engine oil. Bummer! Now my "old mechanics brain" says, "wouldn't it be nice if there was a "weep hole" at the bottom of the pump drive!! -just like old school coolant pumps had used for a hundred years!! JUST SAYING,,,,,, -ain't rocket science,,,

Maybe the teams of engineers involved thought it better to take the chance of ruining an engine, than to have it leak externally and create a fire hazard??

Tech2, I would surely appreciate your comments.
(yeah I know, I'm "over thinking things" again, but it's just who I am,,,)
And Thanks to everyone for putting up with me.