Wear metal levels in low mileage motor oil

[circuitsmith]

It's been said that new motor oil causes a higher rate of engine wear during the first couple hundred or so miles of use.

The only evidence I've seen presented of this are seemingly high metal concentration from early used oil analysis.
A graph of wear metal vs mileage would show a high slope early on then flattening out at higher mileage.

However, those early metals could come from very small deposits left from the previous oil that get dissolved by the fresh additives in the new oil.
Deposits on non-contact surfaces could entrap metal particles.

So, unless the engine was thoroughly cleaned (hot tanked) when the oil was changed wear metal vs mileage might be misleading.

 

[chad8]

That would also apply to a "new " engine. I also question the absolute validity of uoa's. It's time for me hide under my chair and get bombed, so catch ya later.

 

[gathermewool]

I usually ignore all wear metal numbers unless something jumps out at me. Like you said, there's no way to know if these "wear" metals were hidden in a pile of sludge and dispersed by the fresher, more-aggressive add pack. There's also no way to determine what kind of wear it is.

OT: I use UOA results to determine the health of the oil, not the motor. Unless there's a major spike, I rarely even look at the wear numbers.

 

[circuitsmith]

Off topic (bump in disguise):

Yesterday I changed my oil after 6 months and ~1600 miles.
Refilled it with (gasp!) dino Penzoil 5w-30 I got on clearance for $1.92/qt.
No filter change this time.
It gets a new OEM filter once a year or 5000 miles, whichever first.

The car is a 2006 5-speed Matrix.

 

[sbergman27]

Where "jumps out" should probably mean, say, an Fe of over 150 or so at the end of the manufacturer recommended OCI, or whatever the manufacturer's engineers consider reasonable.

One thing's for sure. What BITOG readers generally consider unacceptable for wear metals is totally flipped out. On a typical 3L engine, an Fe level of 100 only represents a few molecules' thickness off the cylinder walls. But there's always someone to say "Drain that Mobil... err... oil... immediately! Right now! In your pajamas if necessary! And refill it with this oil that I like for "fill in the blank" reasons.

This board would likely die if it weren't for the obsessive, white-knuckling, irrational parts of people's brains.