UOA’s without TBN?

[satterfi]

I seems like an oil’s TBN value is good indicator of when that oil has reached the end of it’s useful service.

Oxidation works for some, but not me. Redline oil oxidation numbers are useless.

I don’t think wear metals are good indicator of the oil being shot. It’s too late by then, the oil is already pass it’s useful life and now you are just seeing the results of using spent oil.

Viscosity might be useful, but there are lots of contributing factors to viscosity change. I’m not a big fan of shearing oil a few Cst and then letting oxidation ‘fix it’. That seems stupid to me when I don’t know if the HTHS viscosity is also ‘fixed’ with oxidation after you sheared the oil.

What is the value of a used oil analysis without TBN in a normally functioning engine? I’d rather have just the TBN, minus the extra expense of data that’s not all the useful.

[ January 24, 2004, 06:41 PM: Message edited by: satterfi ]

 

[Al]

I agree TBN is necessary. I also believe the rest of the information is necessary bc there is more to the equation than just the condition of the oil. I think Blackstone is the way to go. I had a suspicion of coolant leak bc of the potassium . And for Ten Bucks Terry explained what each metal meant in the grand scheme of things. With that report in hand my son went to the friendly GM dealer and the found the lower manifold gasket to be leaking-just as Terry had indicated. They probably will do the job for half the price. So realistically-oil analysis have already paid for themselves.

 

[satterfi]

I’m not arguing the value of a full UOA or Terry’s opinion.

My point is, if you don’t know the TBN of your oil, then you’re ignorant of the condition of your oil.

It seems to me that TBN is the most useful measure of how an oil is working in a normal engine.

What's wrong with that logic?

 

[Jay]

What is TBN, exactly? That's the problem. TBN varies widely from lab to lab. Even those labs that claim to be following a certain ASTM procedure don't, because the ASTM protocol isn't cost effective.

I've had oil analysis reports come back to me with absurdly high and ridiculously low TBN values. I'm thinking that I can do without this test.

George Morrison insists that TBN isn't a valid indicator in gasoline engines. He may be right--especially in CA with our low-sulfer gasoline.

 

[Patman]

TBN is definitely a very vital piece of info to have if you're an oil nut like me, however if you're only doing 3000-5000 mile intervals it's honestly not that critical to have. If you look at most of the used oil analysis on here, you'll find most people haven't pushed their TBN to it's lowest limit by any means.

[ January 25, 2004, 06:20 AM: Message edited by: Patman ]