Gearhead Jim

2009 C6 Coupe, A6, Z51
Bought new, now at almost 60k miles
Always use Mobil1 5W-30, changed at 30%-50% Life Remaining (5k-9k miles)

Just as a hobby, I send a sample to Blackstone Labs from every oil change. Lead level is typically 7-9, and other metals are normal.

At 37,096 miles/7,711 on oil (Sept 2011), lead spiked up to 13. Copper was normal, Tin went from 0 to 5. Blackstone said it was probably a particle streak in a bearing, don't worry about it. Sure enough, the next two changes with about 7k miles on each, showed lead dropped back to 8 which is normal and tin was 0.

At 59,458 miles/8,699 on oil (May 2013), lead spiked up to 17.
All other metals normal, copper actually dropped a little and Tin was 1. Blackstone says this is still not a big deal, but they are wondering why it's happening. So am I.

If it's a particle streak, what could be causing it? Could changing spark plugs or cleaning MAF dislodge something that sticks in a bearing?
I don't track the car, though I often corner it hard in the twisties. But on street tires (PS2 runflats) and keeping the oil 1/4 - 1/2 qt above the Full mark, oil starvation seems unlikely.

Any comments on the significance of these numbers, or what do do differently?

Boomer111

EDinPA

Plugs and MAF will not change anything with the oil. How about changing the oil more often then 9K miles. Even without the miles, you should not keep it over a year.

You did not say what filter you are using.

Gearhead Jim

Plugs or MAF cleaning might dislodge something which could become a particle streak on a bearing- maybe.

Oil gets changed about twice per year, never lower than 30% OLR, and Blackstone keeps telling me to go a little longer before changing the oil.

Oil filter is the normal GM.

SpryGeezer

Send next well-mixed homogenized oil samples to two different labs and compare results.

victorf

Unless leaded gas was mistakenly filled or octane booster containing lead was used.

Lead particulate spikes in used motor oil?

Lots of bearing materials in engine internal contain lead, lead alloy or babbit.

Hmmmmmmmmmmmmmm!

R&L's C6

So what do these oil analysis really accomplish? If copper or tin or lead or whatever doesn't come back normal, what does it mean. Has anyone taken proactive measures and ripped apart the engine to see whats going on or does one just worry about it. I don't really understand how these benefit anyone.

michaelinmech

I, for one, think worrying is way underrated. After reading the OP's initial Thread, now I'm concerned about my lead and tin levels. Add those 2 together with worrying about my cholesterol level and I've got some serious worrying material. OK, I'm goona eat some potato chips and have a couple beers and commence to worrying. Though I've gotta watch how many chips and beers I have because I worry they'll make my *** look big in these pants . . . . .

PS: At my last Doctor's visit, my copper level was down nicely

Gearhead Jim

From my OP:
"Just as a hobby, I send a sample to Blackstone Labs..."
On the average; I don't think you can make an economic case for oil analysis on our cars, the way we use them.
On the average, I don't think you can make an economic case for owning a Corvette at all.

But, some examples from my own experience:

We had a Toyota that showed high silicon in the oil, Blackstone said to check the air filter system. Dealer checked and I checked, everything seemed ok. Next test still came back with high silicon, dealer checked and said it was ok, I really got into the system and found a small place where a gasket had become pinched and was allowing some unfiltered air into the engine. An easy fix, and we ran the engine for another 80k miles or so, still running perfectly and no oil usage when traded.

Another car, Blackstone recommended the first few oil changes be done earlier than scheduled, the engine was throwing break-in metals into the oil to the point it might become abrasive.

On our C6, I changed the trans fluid at ~50k (severe service recommendation) and diff fluid, sent samples of both to Blackstone. They said that the fluids and the units were in excellent condition and recommended I go further on the next fill, which is better than just guessing.

Gearhead Jim

There is a difference between worrying and reasonable caution. I certainly don't plan to go tearing into the engine just because of the oil tests, even if GM would pay for it (which they won't).

Depending on how future tests go, I might feel confident that this engine will go 200k-300k miles, or might decide it was prudent to trade in before the powertrain warranty runs out in June 2014/100k miles; or the GMPP expires in February 2017/95,500 miles.

Gearhead Jim

So, going back to my OP:

"Any comments on the significance of these numbers, or what to do differently?"

wrh3

I have used Blackstone for years, it is like a blood test for your car and can identify things early on and give you feedback on change intervals based on your driving conditions- more scientific and conclusive than my oil looked dark so it was due for a change.......YMMV

flange

doing oil analysis is a way to benchmark your system. A single analysis is virtually meaningless. its looking at things over time that allow you to be proactive. for example, if results tend to get progressively worse at each test, you can see a trend, and know you are heading down a bad path. seeing a decent amount of babbitt for example may lead you to open it up and have a look at the bearings and maybe look at end play or clearances, in an effort to prevent a catastrophic failure.

seeing anomolies like that would seemingly indicate some foreign materials getting through the journals and causing mild scoring, but likely not enough to worry about.

then again, there are way smarter guys here than me who can offer more scientific answers.

simplegto

If it is a hobby I would be interested what is in the filter when you get high levels in the oil.

Patman

In reality that is a small spike up for lead, and what they say about a particle streak is quite common. I'm not quite sure technically what that means, but I do know that a lot of people do see it happen on their UOAs from time to time (I've seen it on mine in the past too)

Unless lead spiked up to 20 or 30 all of a sudden, I would not worry too much, especially if all the other wear metals are still within their normal range. What would concern me more were if chromium suddenly increased and then stayed high as that would indicate wear in the piston rings.

I'm anxious to see my very first UOA on my C6, but I'm not changing the oil until the oil life monitor hits 10%, or just before I put the car away for winter storage, whichever comes first. So I've got a while to go.

LDB

For some perspective, numbers like “spiked up to 17”, mean 17 parts per million. The oil in a 6.5 quart oil change weighs about 160 ounces. So 17 parts per million of lead would mean about 0.003 ounces of lead, or about 0.1 grams of lead. That is a teeny-tiny quantity, of absolutely no significance to a bearing’s ability to function. Most of the metals from bearing and engine wear end up in sludge, on the walls of the engine block, or in the filter. But you might ask, isn’t the amount that is dissolved and/or suspended in the oil an indication of how much is accumulating in those other places? Only in a very general sense. If the amount in the oil is grossly high, you probably have a problem. But if it has “shot up to 17” instead of being the “normal 10”, the meaning is far from clear. That’s why the reputable oil companies do their testing by running an engine the equivalent of at least 50,000 miles, then tearing it down and actually measuring wear on the bearings, rings, pistons, valves, cams, etc. Trying to deduce engine wear or an oil’s ability to reduce engine wear by any other means is iffy at best.

My advice is to change oil and filter regularly with good quality stuff, stay off the gas until the engine is warm, and don't worry about the testing. Oil testing simply gives you something to worry about, without giving you any clear indication of how bad a problem may be, or what to do about it. And yes, the big oil companies do oil testing while they are doing their long term engine tests. Trouble is, the oil testing does not reliably correlate with the wear results after tear-down. That’s why they keep doing the wear tests, and that’s also why you should be very cautious about interpreting the oil tests. If the experts can’t reliably predict what’s going on inside the engine from the oil tests, what makes you think you can? And once again, sure, if something is drastically high, there’s probably a problem. But small variations? Unlikely to be reliable indications of significance.