What tests to do for UOA.

[Craig750]

I want to do some tests and need some advice on the relevant test items.

Some of the labs in my country will do a viscosity test at 40C (petrol engine) in a standard test rather than at 100C (diesel engine). I am thinking the 100C test is preferable.

Here is a list of the other items.

Water
Soot
Glycol
Nitration, Sulphation
Oxidation
Viscosity, cSt at 40°C
Viscosity, cSt at 100°C
VI
TAN
TBN
Dispersancy
PQ Index
Fuel Dil.

Elements: Inductively Coupled Plasma (ICP) analysis of wear metals and contaminants and additives - Aluminium(Al), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Tin (Sn), Silicon (Si), Magnesium (Mg), Molybdenum (Mo), Boron (B), Sodium (Na), Potassium (K), Calcium (Ca), Zinc (Zn) and Phosphorus (P)

What can I remove from the list?

Soot, sulphation, oxidation, dispersancy? These are listed for diesel. TBN is also listed but I think that should be included?

Comments please!

 

[d00df00d]

Why not do everything? Cost?

 

[Craig750]

Yes

 

[d00df00d]

What's PQ index?

 

[Craig750]

A measure of particulate iron present in the sample, using a magnetometer. This analysis detects iron particles that are too large to be detected by ICP

 

[d00df00d]

I'd remove VI, soot, sulphation, and dispersancy.

 

[Craig750]

Yes, and PQ I think also.

I thought there were a lot of experts hanging out here. I am surprised no one else has chimed in.

Thanks.

 

[Craig750]

I found out some interesting info about TAN and TBN and I wonder if the oil analysts on this forum that look at these figures use this as a guide for oil serviceability.

Here is the link:

http://www.usoilcheck.com/oilchek/used+oil+analysis/tutorial/tbn+tan.asp

I'll quote the relevant part for posterity and net researchers on the topic.

TAN by itself is of limited value in determining oil condition of an engine oil due to the fact that it represents a combination of different chemical characteristics. The acid-like nature of anti-wear additives found in most modern engine oils cause a high initial TAN. Greatest benefit is derived from the TAN by comparing it to the TBN. TAN increases in service as TBN decreases. The point at which these two numbers meet has been indicated as the maximum useful oil change interval for that type of engine in that type of service. Studies have shown that when TAN exceeds TBN, engine wear accelerates at abnormally high rates.