Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Wear metal levels in low mileage motor oil

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.

There is a special web-site for these discussions… The motor-oil obsessives can pre-lube themselves right out into the Motor Oil Twilight Zone…

I posted this here and at BITOG simultaneously.

I just find it hard to believe that brand new oil would cause more wear than “broken in” oil.

Are you talking about “break-in” oil that comes in some new cars, and should be changed after 500 miles or so? It makes sense this oil would contain more metal shavings suspended in the oil than oil that is used for longer periods.

Each time you change the oil, after you put the new oil in, you start the car, and the oil light stays on for 5-10 seconds before the oil can circulate through the whole system. This oil, having not passed through the filter much since being installed, would naturally have more metal shavings in it than oil that has passed through the filter hundreds of times since then.

These findings confirm what you already know if you read the side of the box your oil filter comes in. Multi-pass efficiency is always higher than single pass efficiency.

I wonder how the oil tests RIGHT OUT OF FACTORY CONTAINER?? Perhaps the test would show high metal concentration in brand new oil since many M.O. additives are based on metallic salts.

“The only evidence I’ve seen presented of this are seemingly high metal concentration from early used oil analysis.”

Not talking about break in oil or the first few seconds.

This is about any fresh fill of oil and how the metal content changes over a few hundred miles.

“I wonder how the oil tests RIGHT OUT OF FACTORY CONTAINER??”

It’s there in bobistheoilguy.

The main wear metals are iron, aluminum, chromium and copper.

Additives use others, like calcium and zinc.

I don’t waste my time worrying about things I can’t do anything about…Throw a can of BG MOA or Bardahl #1 oil additive and call it DONE…

Or use an oil designed for Diesels or motorcycles that still contain a full additive package. “racing oil” is good and 15w-40 multi-engine fleet oil has not been stripped of it’s extreme pressure additives to protect catalytic converters…

I see you’ve missed the whole point of my original post.

Have a great day!

I’ve never seen or heard of this theory. Fresh oil in a fully broken in engine should not normally contribute to engine wear. In an engine with an “upside down” mounted filter, I gues I couldn’t argue with the possibility that there’s a relatively dry moment while the filter fills up, buut in all honesty I can’t guess whether that does any damage due to the residual oil on the surfaces.

I always fill my filter before installing it. But I think I just do it for “why-not”. I can’t swear that it accomplishes anything. My '89 22R engine had a horizontal filter mounting, and it was still running fine at 338,000 miles when the truck got totalled.

Okay, circuitsmith, you read the part about “break-in” oil, but what do you think of the rest of my post, re. multi-pass efficiency?

I agree with you that most likely these wear metals in short term usage of fresh oil is most likely coming from the old oil left in various pockets in the engine.

Plus, there is usually quite a bit of oil left in the bottom of the oil pan when the oil is drained out. Some pans have baffles, and strengthening braces built into them that holds old oil, and most likely wear metals that have fallen to the bottom of the pan.

I bet if you were to drain the oil from your engine for 30 minutes, and then remove the oil pan, there would still be quite a bit of oil and debris attached to the bottom of the pan.

When you pour in the new engine oil, this stirs up the stuff on the bottom of the pan, and gets it dispersed into the new engine oil, which if you then pull a sample, gets picked up, making it seem like you are having more wear at the beginning of a fresh oil change.

I would also wager that if you ran that fresh oil for 100 miles, drained it, poured in another full serving of the exact same oil, ran it identically for 100 miles, and then sent a sample of both for testing, that the first batch of 100 mile oil would have more metals in it than the latest batch of 100 mile oil.


I ran into this story some time ago.  As I recall it made sense.  However the real life difference was far too small to worry about.  Maybe the engine will last 14 miles less.

Here’s a graph showing increased rates of iron and copper accumulation for the first 6-9000 miles or so:

And please don’t interpret this post to mean I’m suggesting anyone should wait 18,000 miles to change oil!