Acceptable Metal Content in Oil Post-Rebuild
 

Built engine folks: how long did you guys continue to find metal flakes and/or a metallic sheen in your oil after rebuild?

Im probably erring on the cautious side here but I found a small amount of metal content in my oil at 460 miles and am curious if I should be concerned or not. Mostly just a barely visible metallic sheen, but I found a handful of barely visible metal flakes in it after running a small sample through a coffee filter.

Motor was just rebuilt with a replaced crank, new main, rod, and thrust bearings, new BE oil pump gears, and a cylinder hone with new rings, and polishing of both sets of camshaft caps and journals. Oil changes were: after first start following Flyin Miata’s ring seating procedure on a dyno, then at 20 miles, then at 110 miles, then at 460 miles. I started feeding in boost at 250 miles. Then I drove it properly hard at 9-10psi yesterday at the 350-460 mile mark. Lots of high rpm/high load driving up in the mountains.

Also worth noting. The motor had zero oil pressure at first start due to incorrect oil pump gears being installed. I started and idled it for about 5 seconds, shut it off, accumulated about a minute of dry cranking time with the spark plugs removed, ran it for another 4-5 seconds, then tore it apart and found/fixed the problem. That being said, I had a liberal amount of assembly grease on all the rotating components and hope that staved off any damage.

I’m running Rotella T4 15w40 for the break in. Oil pressure has always been within spec. Im getting about 25-27psi during 900rpm idle at 180-190*F oil temps. I don’t have exact figures at higher rpm but will try to get them next time I drive the car. Engine pulls great and makes no weird noises.

Can anyone chime in and enlighten me as to if I should be worried or not?


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Coffee filter for reference. Hard to see but the metal flakes are below my fingertip. They didn’t seem to react to a magnet.

I wouldn't worry about it. With that low miles and you raising the boost up recently you are going to see new things breaking in and wearing in just from the added pressures. That's not exactly a huge amount of metal. Could still be Machining debris working its way to the pan.

Thanks, Six. That’s about what I figured but I wanted to hear it from someone with more experience than me.

If it was your motor, would you take it a little easier for a couple/few hundred miles to allow for more break in? Or just keep hammering it and not worry about it. I’m sure the answer is “keep hammering”, but I’m just doing my due diligence here.

Currently running 16-17psi in open loop EBC and was originally planning on setting up/playing with closed loop later this week.

Did you cut your filter apart to take a look, or is this just what you drained from the pan? If you're not seeing bearing material in the filter, I wouldn't worry about it. I don't advocate for babying motors during break in periods either after the first few thermal cycles, but that's just me.

I’ve got the filter sitting on my desk at work, Haven’t had a chance to cut it open yet, gonna do that today.

Yeah, the more I read, the more convinced I was regarding harder break in. Aside from some initial zero vacuum/high rpm decel pulls, I broke my last engine in pretty gingerly and I think it left a little power on the table when I hit the dyno. I’m a little more confident this time so this thing’s getting flogged harder from the start.

Buy oil in the 4-5qt jugs and change it often in the early stages to keep track of how it is progressing. Also check the oil in the catch cans.

I wish I could be more helpful, but I chose the route of purposely not looking too closely at the oil coming out of my fresh built motor. I mean, I saw the light glitter/sheen in it probably for the first ~1000 miles of oil changes (changing FREQUENTLY), but I chose not to cut open oil filters or go fishing with a magnet. Into the recycling bin it went. Ignorance is bliss baby, I figured if it started knocking I'd know. Not saying this is a good idea by any means, but I'm so OCD and have some form of mechanical hypochondria so this worked out for me.

20k+ miles in, 300+WHP, various bad tunes (it's dialed now), lots of track time. Send it!

Thanks guys! Leo, that's about what I was planning on doing. Been working on tuning closed loop EBC the last couple nights and I'm gonna do the next change this weekend at ~700 miles before hounding on it more.

Fire, that's what I did with the motor the first time. Just didn't look closely at the oil that came out at all. In my case, though, it was mostly because I was oblivious haha. Glad to hear your experience went well! Hopefully I have a similar story to tell in a few years.

Yes always nerve wracking when you first build the motor and break it in. I was seeing metal in my oil like you until about 750 miles or so then it became much more typical. I also don't baby a new motor, I run it for 15 minutes then drain the oil. Fresh oil change again at 100 miles, 500 miles and 1000 miles... Then onto regular change intervals. I start getting into boost at like 25 miles in because the rings need to dig in and seat and you only get so much time to do that. Sounds like your motor is gonna do great.

Thanks for the feedback Andy! Yeah, this is only my second engine build (first one spun a rod bearing due to oil starvation lol) so I’m erring way on the side of caution.

As a follow up, I turned the boost up to 17psi after my last post/oil change at 460 miles and spent a few evenings after work this week tuning and beating on it. I changed the oil again at 640 miles on Friday and found basically nothing in it save for a couple miniscule particles that my camera couldn’t even pick up. I understand the interval was pretty short but I wanted to change it before driving it a few hundred miles and flogging it hard again today.


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Anyways, I’m past the point of being concerned about it. If the engine blows up at any point, you guys will be the first to know.

Since we’re still on topic here, this motor feels like it’s making more power than my last one. Maybe it’s just in my head because I’d been driving the car with the stock motor for the last month. Still, I swear this thing has a little more pep than the first time I built it and broke it in easy.

Gonna throw some bigger injectors and a flex fuel sensor on after next weekend’s race then we’ll see on the dyno…

Z, thanks for creating this thread. It makes me much less concerned about the look of my oil out of my fresh engine (spoiler alert).

Haha, I was hoping it'd help somebody. There's a few good threads on this forum that have good data about metal content in freshly built engines, but I still wanted to be safe. Finding info on other car forums was laughable. "iF yOu sEe aNy mEtAl aT aLL iN yOuR NeW mOtOr'S OiL, It'S gOnNa EXPLODEEEE!!!!!!!1!!!"

I'm mildly exaggerating, but not much.

At 1,000 miles on the dot, I did my motor's first two track days back to back and changed the oil after. Still noted some metal sheen but expected it after that beating. At 3,200 miles now and haven't noted any notable sheen or particles during oil changes since then.

I've seen a few of those threads. I like the "if it started knocking I'd know" approach from Fired.

Somebody on a Subaru thread did his first oil change, saw some glitter and was saying, "I'm pulling the engine back out this weekend". No thanks, I'll pull it when it gets percussive.