CAEMI

I write a blog for the SAE and, from time to time, actually look at other blog entries to see if anyone is as witty and interesting as me...

Unless you're a member of the SAE, you can't get on the site and read their stuff so I'm kind of copying some content in here for your information because it was interesting.

This morning I read a discussion of a guy analyzing a "dopped" Cat diesel. They company that owns the engine suspects someone put sugar in the crankcase. The oil was sent to analysis at a lab. The lab report came back showing a high level of CA and ZN (calcium and zinc). The engineering crowd responded that diesel oils have a large amount of zinc and all oils have calcium. Zinc was removed from gas engine oils because it screws up the...wait for it...oxygen sensor and catalyst beds.

So, if you're having O2 sensor failures or your exhaust stinks, are you using a diesel oil?

Next, another poster wrote: Oil analysis is a complex subject. Assuming the sample was taken from a warmed up engine and in a flowing stream to get a representative sample, then we can proceed. What level of Ca and Zn were observed? 2000 to 5000ppm of Ca and 500 to 1000 of Zn is typical of most diesel oil additive levels. In addition to what should be in the oil chemistry, there are possible contaminent sources like water, ambient dirt, wear particles from engine parts. Comparing all the elements in the subject oil to those from similar engines operating in the same fleet would provide appropriate baseline data. If you have evidance of sugar or any other contamination, drain and flush the oil several times, then refill and operate for a short time and resample and reanalyse. If results are still poor, then teardown and inspection maybe required.

Still other guys wrote:
On another note and a useful tool for all that may be here at Engineer exhange, consider joining Dyson Mobility Weblog ( DMW) for a NDA controlled safe place to exchange ideas about lubricant,fuels R&D and analysis.

Related to the CAT engine you are working, Brian is right on, normally calcium ( Ca) is a major part of the detergent additive package but it can also be coolant contamination or water residuals. Zinc is part of Zinc Dithiophosphate Extreme additive package. Rarely would you see Zinc ( Zn ) as a wear component. Do you know what protocols were used for the oil analysis result you refer to above ? I would be happy to interpret that data here for all to see if you can post it here.


All in all, the suggestion was that the engineer doing the study refer to this website: http://www.api.org to gather up some further confusion on the subject.


What I took away from this is not only are the oils becoming more sophisticated and application-specific, it is getting harder and harder to tell which oil to use in older vehicles when the SPECIFIED oil is obsolete.

Rmart30

Im going to call foul on this one..... I have run either delo or rotella diesel oil constantly in at least 2 gas burners for 10+ years and thousands of miles and have had no problems at all with O2 sensors or converters.

Not saying it wont mess up some vehicles, but it hasnt had any effect on those 2 above or my XJ which has had a steady diet of Delo for almost 3 years now.

Diesel

You dont know that unless youve torn apart your engine from top to bottom.

Besides, diesel oil robs the engine of lubrication on startup.

TheJerm

I would say oil is getting better so i dont see a problem with using better oil in older cars. My jeep just gets the regular dino that is on sale, while might not be the best, but i dont care cause its still running great at 210k miles. When i build a stroker, i am going to use a high end synthetic to protect the money and effort put into the motor and from the abuse ill put it thru. Heck at one time i was running 2 qts of diesel fuel in my oil to help get rid of all the sludge this engine had.

I think the combination of better machining and oil's are the reason its not uncommon to see a vehicle over 200K and still running strong too.

I dont think the oil is as crucial in a passenger vehicles then it is a 1/4 million+ dollar machine that is going to work day in and day out for the next 20 yrs, or a semi that will run well over 1 million miles in its live. Cars are meant to be disposable or else they wouldnt be so cheap

CAEMI

x2...exactly what I think, too.

I posted that stuff because so many people have O2 sensor issues and plugged cats, etc. I use Mobil One in my XJ because that is the only oil the DPO ever used so why change. I switched over to Mobile One for my other cars because I don't like to have multiple brands, viscosities, around. I'm moving to 5w20 for everything except the tractors...they get Rotella 10w30 because they're diesels.

Rmart30

The OP stated that the diesel oil screws up oxygen sensors and catalyst which have nothing to do with INTERNAL engine parts.

And although I have not torn down either of my engines and checked them under a microscope and micrometer after 120k on "diesel oil" I use no oil between changes and the oil pressure is the same as its always been.

I will loose no sleep over using diesel oil in my gas engine.

rich

I dont beleive you really need high doses of zinc anyways,after the motor is broke in. I would think what amount that is allowed in the regular automotive oils today is enough. But who knows for sure? Motor oil has as many myths as the cooling system of an xj. (castrol synthetic oil used here)

Programbo

lurk520

I'm impressed you have an oil pressure gauge that actually works....