UOA vs Teardown results

[Gary Allan]

Originally Posted By: Spector
Even if you had a UOA trend and that trend showed an increase in lead, copper etc the truth is, would you tear down that engine and rebuild it or trade the vehicle etc. Honestly now, tell the wife hey, we need to dump this car or put in a rebuilt because I am certain the engine is due for failure soon based upon increasingly disturbing wear metal results in my UOA! That would really go over well so the answer is--- In all probability, NO. I had this scenerio on one Vehicle, I believe even Terry thought I was headed for a catastrophic failure, but that engine lasted 3 more years and traded it still running.

I have spent a small fortune on UOA, I did this for about 10 years then evaluated the results and said, guess what, not only does it not make any difference, but I concluded that even if I saw a terrible trend I would do nothing anyway (other then a coolant leak ) so why bother tormenting myself and wasting the money!



Well, a coolant leak and the aggravated numbers would be a good reason for UOA. My one personal service customer had a GM LIM engine. UOA confirmed the condition. She tried the cheaper remedies ..they didn't work. She traded/sold the vehicle.

It saved her from the escalating costs of an older car that's otherwise in good shape ..but will start requiring more expensive service procedures to be performed (AC failures, rad, etc..etc.)

 

[Whimsey]

My wife had a bought new 2002 Explorer with the 4.0 V-6. Afterwards I found out about the timing chain tensioner failures. I had the UOA done for a 10,000 mile OCI at around 40,000 on the odometer. It was just fine with very low wear metals. At around 47,000 miles, after changing the oil at 40,000, due to the chain tensioner problems with these engines I again had Terry do an UOA. I had very high iron in the UOA. This was indicative of the timing chain failure. Ford's answer was to replace them with the same failing timimg cassettes. This could cost well over $3,000 only to fail again.

My wife traded the 2002 XLT 4.0 for a 2005 4.6 V-8 EB during "Ford's employee pricing" time period for less than she paid for the 2002. Plus she got great trade in on her 2002 because of it's great condition.

My point is Terry saved me lot's of money due to the UOA.

Whimsey

 

[Pablo]

UOA's are fun. Bottom line.

 

[BuickGN]

Originally Posted By: Pablo
UOA's are fun. Bottom line.


Ah nevermind. First drun k post on BITOG.

 

[Spector]

Whimsey?
Your comment"
This was indicative of the timing chain failure


you never did determine the actual cause of the high iron and replaced the vehicle due to suspected future chain failure. We will never know and to say that the UOA was the indicator that a failure was in the future is speculative.

But, whatever lets one sleep at night is the answer as to whether UOA are worthwhile

 

[ARB1977]

Untill i sence there could be an issue, using coolant or oil buringing thats when i may consider doing a uoa. I feel i do my maintence at respectfull intervals...thats about all i can do and hope for the best. So far its working.

 

[Pablo]

Originally Posted By: BuickGN
Originally Posted By: Pablo
UOA's are fun. Bottom line.


Ah nevermind. First drun k post on BITOG.


I meant "fun" in the interesting/curiosity kind of way.

 

[ekpolk]

Originally Posted By: Pablo
UOA's are fun. Bottom line.


That too. A shared bottom line for sure, but still, undeniable.

 

[ekpolk]

Originally Posted By: BuickGN
Originally Posted By: Pablo
UOA's are fun. Bottom line.


Ah nevermind. First drun k post on BITOG.


Starting a little late, aren't you???

 

[BuickGN]

Originally Posted By: ekpolk
Originally Posted By: BuickGN
Originally Posted By: Pablo
UOA's are fun. Bottom line.


Ah nevermind. First drun k post on BITOG.


Starting a little late, aren't you???

I drink twice a year. I had 3 beers, had to call it a night while I was still upright. You can imagine the comments I get when people see 3 beers stagger a 220lb guy. I'm a cheap date.

 

[BuickGN]

Originally Posted By: ekpolk
Originally Posted By: Pablo
UOA's are fun. Bottom line.


That too. A shared bottom line for sure, but still, undeniable.


I'll give you guys that one. I'll still likely do a few on Redline just to do them.

 

[aquariuscsm]

I`d love to do a couple on my car........one with yb 20W50 and one with M1 15W50. Like it was said,just for kicks.

 

[JAG]

Originally Posted By: BuickGN
Originally Posted By: JAG
UOA wear metals only measure particles small enough to be measured and the particles need to make it into the oil sample bottle. Different particle size ranges do occur with different oils, different engines, different driving styles, different dirt contamination, etc. Different sampling methods can also affect the particle sizes captured as well as the concentration of them. Different particle sizes affect how likely they end up in the oil sample bottle.

So there are many pathways for the results to be underestimated (relative to true concentration). If comparing one result that had less underestimation to one that had more underestimation, that one result will appear elevated.

But if you hold as many variables nearly constant (including the specific oil used and having used it long enough for stabilization to occur) and do several UOAs back to back, trending can generally allow decent conclusions to be made.

I say generally because there is still the possibility of severe wear occurring and the particles are so large, that the UOA results greatly underestimate the true wear rate. If severity of wear goes up from there the results will be an even greater underestimation and it will be hard or impossible for the UOA reader to catch it. This situation is not common but it does happen to those unlucky enough to be in it...like BuickGN was. It's also happened in VW 2.0T engines where severe wear has occurred in certain parts of the valvetrain.

Since different oils generally produce different wear particle size distributions, I think it is generally unwise to say that based on a set of UOAs, one oil is causing less wear than another. Again I say "generally" but not always.

Adding a PQ Index test to a standard UOA, as Gary mentioned, greatly helps get a better estimation of true iron wear rate. But that still is based on what's in the oil sample bottle so that needs to be as representative as possible the ideal: the entire oil in the engine with all iron/steel wear particles homogeneously mixed in it.


I agree with this. Considering the engine went from new to completely trashed in less than 10,000 miles, it's likely my wear particles were larger than normal. But wouldn't you think that there would be SOME smaller particles? Even if it came from the larger ones getting ground together.

Yes I would expect to see some smaller particles. It would be informative if we could see the UOAs.