High Lead Reading in Corvette, Twice.

[hotoil]

Blackstone confirms there are no titanium parts in my LS3, and no titanium in M1. But the GM Dexos oil does contain titanium, he said my reading is about what he would expect from a couple of qts of GM Dexos mixed in with my M1. Last oil change was at the dealer, none added during this run. Hmmm...

Also, he said that the high lead readings are unusual but not necessarily a problem. If the bearing were badly worn, we'd start to show copper which is underneath the lead. And lower oil pressure, which is not happening.

In other words, enjoy the car and see what happens on the next sample.

 

[OVERKILL]

Originally Posted By: 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?


Interesting. What oils were this with, given that you seem to have changed to Castrol?

 

[OVERKILL]

Originally Posted By: 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...


Don't worry, you can safely ignore Merk, he has no idea what he's talking about and just likes to troll.

 

[MolaKule]

The 5.3L Corvette engine in my 2008 TrailBlazer shed copper and lead for quite a while. It didn't matter what oil I used - whether it was my own super-duper formulations or Over-the-Counter oils.

However, it was always trending downward as the mileage increased.

Looking at the UOA's, it didn't really start to trend downward until after 75k miles.

My theory is 1.) GM used some type of CuDTC/Lead naphthenate type of assembly lube, or 2.) had some kind of sacrificial CuDTC/Lead naphthenate pellet imbedded somewhere.

 

[hotoil]

Originally Posted By: OVERKILL
Originally Posted By: 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?


Interesting. What oils were this with, given that you seem to have changed to Castrol?


No Castrol, still using Mobil1 5W-30 from the beginning. Or trying to, it looks like the dealer may have put a couple of quarts of the GM in during the last change.

 

[hotoil]

BTW, some people have asked about oil pressure.

When the car had about 1,000 miles, I warmed it up to exactly 180'F oil temperature; then checked the oil pressure at idle and at 2,000 rpm.
The numbers were 31 and 47 psi.

Today, with over 84k miles, I redid the test at the same temperature and rpms.
The numbers were 33 and 49 psi.

Probably, that means I got a bottle of slightly thicker Mobil1 5W-30 than the previous test. Or maybe the OP readout is starting to read slightly high.
More likely, it means that the bearings are doing just fine.

Time to go for a drive...

 

[OVERKILL]

Yes, that engine sounds perfectly healthy bearing-wise based on those readings. Drive it

 

[tig1]

Originally Posted By: OVERKILL
Yes, that engine sounds perfectly healthy bearing-wise based on those readings. Drive it

+1. UOAs do more to cause stress to more owners of vehicles than most any other reason, and what is accomplished? Nothing.

 

[Pontual]

A lighter wallet, that is ...

 

[hotoil]

Originally Posted By: tig1
Originally Posted By: OVERKILL
Yes, that engine sounds perfectly healthy bearing-wise based on those readings. Drive it

+1. UOAs do more to cause stress to more owners of vehicles than most any other reason, and what is accomplished? Nothing.


Well, in our Corvette it looks like the dealer gave me a mix of M1 and GM Dexos at the last oil change, that's worth knowing.

And a Blackstone report alerted us to an air filter leak in a Camry that neither I nor the dealer found, or could find even after the alert. But next time around, Blackstone was emphatic that there was a leak, and we kept searching until we found it.

We'll need to (hopefully) wait a few years to discover if our Corvette will go 200k miles like most of them seem to do, or die early like a few of them (non-raced) do.
Stay tuned...

 

[SteveSRT8]

We are always obsessing over UOA's here. Way too much importance for miniscule readings subject to error...

 

[Cujet]

My turbocharged 1.8L, 385HP Miata engine started showing high lead. If I remember correctly, the last UOA was 255 ppm Pb.

I overhauled the engine due to significantly shortened connecting rods (too much cylinder pressure actually shortens the Miata's rods by about 1/4 inch) and the resulting low compression.

I also tried 0W-20 Mobil 1 in an attempt at getting more high RPM power. This directly resulted in high Pb.

The bearings were not all that bad, and the crankshaft was perfect. If the engine did not have other problems, the rod bearings would have held up indefinitely.