What causes high oxidation of an oil

[DrDusty86]

I have had extremely high oxidation of the oil showing up in the last two UOAs. Milage on oil samples were 5670miles with 113 idling hours and 5700 miles with 110 idling hours. My previous changes had the same milage and close to the same idle time and my oxidation was only 13, now it's 41. What gives?
Dusty

 

[dave1251]

A common problem of oxidation is high acid. Another cause that increases Oxidation is higher the temperature of the lubricating oil increase the rate of oxidation increases. But you have to be careful because TAN could be a useful tool but because some additives are acidic or become acidic in use and could mask the effects of oxidation of the oil. Also oxidation can causes oil to increase in viscosity. What oil are using just curious?

 

[DrDusty86]

I'm using RP SL 5w30.. the vis is 11.0. My TBN is 6.5.

 

[vinu_neuro]

High temperature, fuel ingression over an oci. The second one for most people.

 

[DrDusty86]

Should I shorten my interval?

 

[vinu_neuro]

Did you post them in the UOA forum? I don't see anything from you recently.

 

[DrDusty86]

I did several months ago. I have the print outs in front of me..

 

[dave1251]

I would not adjust my OCI just yet. Is wear trending upwards on your UOA's? I would just do some basic checks to ensure the engine is running in peak condition. The simple stuff is when was the last time you treated your fuel system, checked PCV, spark plugs, even things like air filtration, and fuel filtration are somethings to look for. Does this particular engine had any issues with blow by?

 

[Pablo]

Originally Posted By: DrDusty86
I have had extremely high oxidation of the oil showing up in the last two UOAs. Milage on oil samples were 5670miles with 113 idling hours and 5700 miles with 110 idling hours. My previous changes had the same milage and close to the same idle time and my oxidation was only 13, now it's 41. What gives?
Dusty


The oil formulation MAY have changed. I have no idea if it did - but an oxidation number without comparing to the actual virgin oil you are running is useless. Was the first number from the exact same batch of oil?

Originally Posted By: DrDusty86
I'm using RP SL 5w30.. the vis is 11.0. My TBN is 6.5.


Again all the oil from the same batch?

 

[BMWTurboDzl]

Excessive foaming? (i.e. microdieseling)

 

[DrDusty86]

Yes, it is the same batch Pablo.
Dave, The engine is 100% up on maintence and runs excellent. I have pulled the dipstick out while it was running and took the oil cap of and no smoke.
Done: PCV valve-1 year ago
Air filter- 6 months ago
Fuel filter 6k miles ago
Spark plugs/wires OEM about 20k ago
Belts, hoses, coolant, rad cap-OEM
Treated it to Techron concentrate 10k ago
Wear seems to be fairly consistently low

 

[dave1251]

If wear has been consistent and low. I would not read into oil oxidation too much. 11 CST is still a 30 viscosity range and your data sample is from two OCI's if I am reading this correct?

 

[DrDusty86]

It is over 4 UOAs, I just posted 2.