UOA question

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989
Location
Florida
On a vehicle you purchased new, how many miles on average would you consider waiting to know all break in material is going to be out of the engine. 20K? maybe
 
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2,857
Location
High Tax Illinois
I've mainly done this. Change oil/oil filter at 500 miles. Change oil/oil filter and rear gear oil at 1500 miles. Car now has 2000 miles on it. To me anything that is going to wear out is done. The next oil/oil filter change will be at 5000 miles. Now I would normally start "my maintenance" schedule. I've never gone over 5K miles on oil change. The next rear gear oil change will be somewhere around 15K miles, the next around 50K miles. To me oil/oil filters are the best and easiest thing to keep your car running correct. I don't care about the guy that goes 11,258 miles between oil changes. When I sold my 2003 Dakota 3.9, I had two guys basically bidding back and forth to buy it because of how I took care of it. It's still running around here with over 200K miles on it and nothing has needed to be done to it. That's me............How anybody else does their vehicles is their business.
 
It depends on how often you change the oil. I made a post yesterday where I am fairly convinced that most of the "break-in wear" is accumulated during the first 500 miles, because machining techniques and part finishes are much smoother than in the old days. How long you run the factory fill and short OCIs after that determine how much "wear" shows up in the UOA. Here's my mom's 1st UOA at 26k. You can see all the wear numbers are extremely low, and she had four prior oil changes to flush out the residual wear that is left in the portion of the oil that doesn't drain out of the engine during an oil change. Whatever wear accumulates during the initial fill of the engine must be diluted by new oil changes to help remove it from circulation. So the first change if the engine retained 15% of the oil, that's nearly a quart with very elevated break-in wear. At say 80ppm, and you add 4 quarts of fresh oil, now you're down to 16-20ppm. The next change should drop you down to around 11-13ppm, and so on. It should take at least 3 oil changes to flush a majority of the break-in wear out and get down to the engine's "normal" UOA signature. Copper oil coolers sometimes take longer to trend down, and will always run higher than what most people are used to seeing, but it's harmless.
 
Messages
1,564
Location
UT
I know this is going to be controversial, as there are a lot of old school car people here. But I'll share it anyway. When I bought my Outback, Subaru specifically recommended leaving the factory fill motor oil in for the full recommended oil change interval. Their explanation was twofold. First, they explained that modern engine manufacturing and assembly processes are so much better than those of yesteryear, that engines assembled today are not at risk of having metal shavings and debris inside them. Second, they explained that there is benefit to leaving the factory fill in place for the full oci, so the additives could do all the good they are intended to. I know that is a really hard concept for many. I couldn't do it either. I did the first oil change on my Outback at 900 miles, then changed the filter at 3700 miles before starting oil changes at the Subaru recommended interval.
 
Messages
17,061
Location
Upper Midwest
Originally Posted by BHopkins
First, they explained that modern engine manufacturing and assembly processes are so much better than those of yesteryear, that engines assembled today are not at risk of having metal shavings and debris inside them. Second, they explained that there is benefit to leaving the factory fill in place for the full oci, so the additives could do all the good they are intended to.
I don't think that's controversial at all. On the other hand, those shavings and bits (the damage causing ones) aren't what show up on a UOA anyway. Often times we see people on here post UOA from new engines and then get comments like "OMG get that oil out of the engine now!" when in reality the metals being indicated on that UOA aren't the ones causing damage. One really does not know how much damage causing material there is in a standard UOA unless further sample processing is performed, such as an acid digestion. I've let all my new cars run the initial fill out to the recommended OCI and I've gotten over 400K on my Sienna without excessive oil consumption or other oddities. Same situation for my ECHO and the Accord.
 
Messages
11,342
Location
Florida, Cape Coral
UOAs on a SAAB, a Subaru, MAZDA CX7 and a MAZDA CX5, I observed the wear values stabilized at ~ 7-8,000 miles although the significantly drop in wear values occurs at ~ 3,000. I'm sure Burnishing continues well after the 8K miles. Ed
 
Messages
1,640
Location
California
My answer depends on the recommended service interval. If the OCI is 10k, then sampling at 20k will only be 2 services and I'm pretty sure there will be elevated break-in materials showing up on the analysis. I would wait at least 30k miles AND 4 OCI before doing any kind of oil analysis.
 

dnewton3

Staff member
Messages
8,485
Location
Indianapolis, IN
I agree with the above. Don't look at this as a function of miles, but more a function of the OCIs completed. I would advocate for at least 3 OCIs prior to any UOA on a new piece of equipment. When I got my new Taurus sedans, I did OCIs when the vehicles reached 1k mi, 4k mi, 10k mi; three flushes to get out the residuals. Now we're coming up on 20k miles; the break-in is long gone and the "normal" wear should be fairly consistent.
 
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