High Lead Reading in Corvette, Twice.

[hotoil]

2009 Corvette Coupe, LS3 engine, A6 trans.
Bought new, now at almost 60k miles
Always use Mobil1 5W-30, GM filter, 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 (recommended 1 qt above for real racing), oil starvation seems unlikely.

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

 

[dave1251]

Do you use fuel system cleaners?

 

[Clevy]

K. I'm not an expert but are you saying that you are concerned about 9 ppm? I know that M1 is known for sometimes having higher than what's considered normal or average however 2ppm per 1000 miles doesn't sound to me like the engine is dissolving.
I wouldn't worry. Drive er,enjoy smoking the tires and cornering like its on rails. The engine will last umpteen hundreds of thousands of miles.

 

[Eddie]

7-9ppm of Pb is not high.

 

[dparm]

It's consistent, and that's what matters. I wouldn't sweat it.

 

[hotoil]

Originally Posted By: dave1251
Do you use fuel system cleaners?


Once per year, I put a bottle of "GM Fuel System Treatment +", which appears to be re-branded Techron, in the fuel tank. That was done just before the recent oil change that showed high lead, so anything in the Fuel Treatment could have ended up in the oil. But Blackstone said they were not aware of any gasoline additives that would add lead, except for some octane boosters; I don't use those.

But do you think differently?

Also, the injectors/MAF sensor/throttle body; were cleaned; and the spark plugs changed, just before the oil change last Fall that showed normal lead. But if they dislodged something that became a particle streak, it would have shown up in the recent oil change/analysis with the high lead.

I have no idea if these are possibilities, or not.

 

[hotoil]

Originally Posted By: Eddie
7-9ppm of Pb is not high.


I agree. But I have two samples (37,096 miles and 59,458 miles) where the lead suddenly jumped from 8 or 9 to 13 or 17. Two changes in between with lead at 8 or 9, which was normal.

Not a disaster, but Blackstone and I are wondering why this is happening.

 

[OneEyeJack]

If the readings don't go anywhere then there is nothing to find. Unless you want to try investing in something like Atomic Absorption Spectroscopy to discover where the offending particles originated just accept that the lab's guess is as good as it gets and your engine will do just fine. Some day down the road in a time far, far away when the engine gives up the ghost or you total the car you can do a careful tear down and examine your bearings and find a tiny streak somewhere. And the journal will probably be perfect and that means that the bearing did its job.

 

[jigen]

I would be very happy with these numbers and 7-8k OCI's in an LSX engine. They always show a fair bit of metals. I wouldn't worry about it whatsoever.

 

[tig1]

The acceptable level for lead is up to 100PPM. Notice that lead and other metals are often higher with GM engines than others, but we know that doesn't have anything to do with actual engine wear. This is where UOAs are mis-leading and are not of any real value.

 

[Corvette Owner]

Mobil 1 was hard on my bearings of my 1998 Corvette, see:


http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1866161&page=1

Excerpt:

Here are my "increased lead" readings (note: I do not do a UOA every oil change)

Miles / Lead (ppm) / (Date) / miles on oil sample / Oil used

64,168 / 7 / (5/2003) / 6,036 / Mobil 1

95,517 / 11 / (4/2006) / 5,773 / Mobil 1

107,315 / 20 / (9/2007) / 6,127 / Mobil 1

113,499 / 18 / (6/2008) / 6,183 / Mobil 1

125,459 / 6 / (4/2010) / 5,778 / Castrol Edge

Note that the lead number went down significantly after I switched to Castrol Edge. Three times less !

 

[cptbarkey]

all chevy engines shed metals like a cat in the jungle.

 

[901Memphis]

How about adding a filter mag to reduce iron in the oil thereby possibly reducing other metals? Can't hurt and it sounds like you can afford it. I wish I had a filter cutter to see what my filter mag picks up on m1 in my Taurus on a 10k oci.

 

[dave1251]

Originally Posted By: hotoil
Originally Posted By: dave1251
Do you use fuel system cleaners?


Once per year, I put a bottle of "GM Fuel System Treatment +", which appears to be re-branded Techron, in the fuel tank. That was done just before the recent oil change that showed high lead, so anything in the Fuel Treatment could have ended up in the oil. But Blackstone said they were not aware of any gasoline additives that would add lead, except for some octane boosters; I don't use those.

But do you think differently?


Also, the injectors/MAF sensor/throttle body; were cleaned; and the spark plugs changed, just before the oil change last Fall that showed normal lead. But if they dislodged something that became a particle streak, it would have shown up in the recent oil change/analysis with the high lead.

I have no idea if these are possibilities, or not.



I do not think differently. I know there are fuel system cleaners that cause increased bearing wear, but techron is one that does not. If every 3rd or 4th oil change there is a slight increase wear I would not worry.

 

[Geoff]

A guy on the camaro5 site posted a UOA with Pennzoil Ultra with excellent results. Also an LS3.

Also what were the respective silicon levels in the UOAs above?

 

[hotoil]

Well, a couple of years have gone by and here's a comparison:

50,759 miles on car; 7119 miles on oil in Sept 2012:
Lead = 8
Copper = 90
Titanium = 0

84,414 miles on car; 9,188 miles on oil this month:
Lead = 22
Copper = 61
Titanium = 8

So the copper is slowly decreasing, but the lead is steadily increasing to numbers that seem higher than others have, and titanium had always been 0 but suddenly it's 8.

Any ideas what this is telling us?

 

[Merkava_4]

Originally Posted By: hotoil
Always use Mobil1 5W-30


That's your problem right there.

 

[Nate1979]

Have you cut open the oil filter? I would be curious to see it.
Have you tried a different oil? If not it cant hurt to try something different.

 

[hotoil]

Originally Posted By: Merkava_4
Originally Posted By: hotoil
Always use Mobil1 5W-30


That's your problem right there.


There's a lady who just traded her 2008 Corvette (same engine as mine)at 250,000 miles. Engine had never been opened up, still running great, she used Mobil1 5W-30 and changed only when the indicator told her to. Lots of other people with similar history.

A different oil might be a little better or a little worse, but won't the change the basics of what is or is not happening inside my engine.

Someone said that there are no titanium parts inside a LS3 and none in Mobil1. Hmmm...

 

[spasm3]

Is the GM filter an e-core? I'd probably run a m1 filter or fram ultra over the e core.