Nitration

[Gene K]

The Nitration limit on my diesel is 25 abs/cm via FTIR. I find I am approaching this while my TBN is still over 6.0 on conventional oil. Any thoughts on why I may be having this issue? Could the base in the oil be ineffective?

 

[Jim Allen]

No idea off hand but an interesting quandary. What it the virgin TBN for the oil? You may as well tell us what oil too, for context, and what engine and situation. Are you using any fuel additives or unusual fuels?

From what I understand, Nitration is very uncommon in diesels but most common in natural gas powered engines. Nitration comes from the combustion process when the nitrogen in the atmosphere is oxidized. Apparently, higher combustion temps are more prone to causing this and that's why gas or CNG engine have more trouble with it. It usually cause sludge and oil thickening.

I think piston ring blowby (and/or poor crankcase ventilation) and EGR issues can cause an increase in Nitration in a diesel, so you might check those.

 

[JAG]

Edit: Jim beat me to it on many points and we typed at the same time but here goes:

Nitration is from oxidation of atmospheric N2 in the combustion chambers. Some of that ends up in the oil and those reaction products tend to cause varnish and carbonaceous deposits, oxidize the motor oil., lower TBN, and raise TAN. So a given amount of nitration just means there is that much detrimental reaction products in the oil and better oils will better prevent deposits, neutralize acids, and thicken less. A fixed condemnation limit on nitration does not make sense to me.

Amount of blow-by is one of the factors affecting nitration levels.

 

[avss1]

You can find Nitration even in VOA due to presence of N-components in formulation. Here it is VOA/UOA of diesel ACEA E-4 high TBN oil.
Initial Nitration level - 18 (highlighted yellow) and after 42000 km - 36.
http://manesu.com/uploads/1102/11/70/1574eb8325218b1f.jpg
Sorry for Russian version

 

[Gene K]

Engine - 14.0L Series 60 Detroit (Non-EGR) set at 600 bhp and 1950 Torque. 650,000 miles. Oil Capacity 40 Qt.
Still Uses 1 Qt every 3,000-4000 miles and gets 8.0 mpg as it has since new. Has a Road Draft Tube instead of PCV.

Fuel - D100 to B20.

Oil - Shell Rotella T3 15W40 (Initial TBN 10.6)

Mileage on Oil - 30,000 miles.

 

[Jim Allen]

Yeah, that doesn't sound right. Have you consulted with a lab at all on this? I presume that's where you got the condemnation limit. This is beyond my experience but if faced with this myself, I'd probably want to know what the starting point was for the new oil and verify that condemnation limit via a few other sources. If it is indeed high, it comes back to piston rings and blowby or some other factor. Perhaps the Bio content. That might be another source of research for you to determine if the B20 is having some negative reactions. If you find an answer, would appreciate a heads up.