Soot

[Roger3116]

Whay is a good number for soot when doing a UOA on a diesel engine? How much is too much? Roger

 

[Doug Hillary]

Hi,
All engine makes are different in regard to soot generation and handling
With my heavy engines, Detroit Diesel ( DDEC 4 - 60 series ), Detroit state 3.00 ppm is the max. using a CH4 mineral oil
ExxonMobil in Australia will tolerate 3.5 ppm with Delvac 1 and have indicated that Delvac 1 will tolerate more

I change mine at/before 3.5 ppm on Delvac 1, depending on TAN and etc

Regards
Doug Hillary

 

[Roger3116]

Hi Doug and thanks for the reply. We must be using a diferent scale because the soot in the UOA for my 3116 Cat is around 90 and they say it is OK. Any ideas? Roger

 

[Jim]

It depends on how well the oil is filtered. With a Spinner filter I have gone as high a 6% soot in the oil. The soot that is in the oil is too small to do much harm. The viscosity starts to go up at that point so I need to change it. This is in a Mercedes 240D

One of the posters on the TDI club found that the soot generated by a direct injection engine looks different (using a scanning electron microscope) than soot from an indirect injection engine. It seems the carbon forms rings in a direct injection engine so it is more abrasive than the flatter soot generated in an indirect injection engine.

 

[Doug Hillary]

Hi,
sorry, I have made an error in my previous post here quoting soot as ppm. It is in fact %

ExxonMobil's Lab. here uses an infra-red soot measuring process ( close to TGA Mass %( E1131 )) using the virgin oil as a reference, as I understand it

So in my previous post the "ppm" should be read as "%" - sorry!

Regards

 

[Roger3116]

Hi Doug-----so what do you change it at---96? Roger

 

[Doug Hillary]

Hi,

Roger3116,
I change the oil at around 3.00%. Since starting the analysis programme some years ago the highest reading has been 3.58% and the lowest at 2.90%

ExxonMobil had initially set a limit of 2.00%. But when Detroit lifted their limit from 1.5% to 3.00% when using CH4 mineral oils, the ExxonMobil limit was adjusted to 3.5%

The main criteria for change I use is distance - no more that 62000 miles - adjusted down by the TAN at/above 8, viscosity being outside ExxonMobil's limits, any dangerous contaminants and unusual wear metal movements etc.

At 62000 miles Delvac 1 is still suitable for use and it is probably only my conservatism and the service /inspection regime that I use that inhibited longer intervals at this stage
The amazing thing to me is that the viscosity has always been within limits. Our average has been 86, with the lowest 74 and the highest 90. The limits we use are, low 72 and high 119

The individual distances on my trucks discussed here is now between 510-550000 miles

On any new truck I purchase I will continue to use the Mann-Hummel "Spinner" and go to longer OC intervals using analysis on Delvac 1 CI. I will also install a self-greasing unit to enable adjustments to the service schedule

Regards