Lead levels in UOA -What is high?

[Russell]

Can some one help me understand the meaning of lead levels in a used oil analysis? For example, will switching from conventional to a synthetic cause the lead levels to "appear" to be high for a long or short period due to cleaning. In addition, what is a high level to expect in older engines, specifically BMW 6 cylinder engines?

My last two used oil analysis with Mobil 1 0w40 on my car had, per Blackstone, high levels of lead at 23 and 40 PPM with less than 4,000 miles for each OCI/filter change.

Not sure I have any concern as I may still be having a lot of cleaning going on. BTW, I switched to Mobil 1 Truck and SUV 5w40 with my latest oil/filter change.

TIA

 

[Russell]

Pablo thanks. No leaded gas since I have driven the car for the last 35,000 miles. Use chevron surpeme gas with techron. have not used techron additive for over 120,000 miles, only FP60

Why are these (23-40 pmp) lead levels considered high? I saw on another post that iron at these levels is not high. Just trying to understand.
TIA

 

[Curious Kid]

I would think that given the small surface area where lead is present (bearings being the only area that comes to mind), make a given count more critical than other more prominent element types, especially for it's location and dependence in the system.

As far as changes with different lubricant use, perhaps it has to do with a wash-out effect, releasing entrapped element residue...or perhaps the different chemisries are competing for surface area about the load zones, leading to momentary increases in wear. In all honesty...

 

[Pablo]

Can't specifically address the BMW questions, but if my cars produced 23 or 40 ppm in 10000 miles I would be worried.

That said - Pb can come from several sources and it is not always something to worry about. The Pb could have come from an additive or leaded gas, for example. Yes there does seem to be some slightly elevated Pb when switching to certain synthetics - especially those with certain esters.

This is why trending is better than single data points.

Maybe make a baseline. Do an AutoRx clean with a conventional oil, with a good rinse. Then do a 3K run with a conventional HDEO and get an analysis. Then do the Mobil 1 Truck and SUV 5W-40m analysis.

 

[Pablo]

As curious kid basically said - it's apples to oranges to compare two different metal levels.

Again on the practical side, assure your engine is clean (easier said than done) and run a baseline.

 

[Russell]

Pablo-Thanks You are correct, I need to know for sure the engine is clean.

I thought that Mobil 1 synthetic was supposed to clean the inside of your engine. Now I am not sure, or at least it takes a long time.

You see, the PO went 9,000 miles or so before having the dealer change the 15w40 or the ocasional conventional 5w30 oil. He went by the oil service lights. Therefore, I suspect the engine was a bit sludged up.

I may do an Auto-RX treatment. However, I am a bit concerned over the time and effort needed. Even so, I may do a used oil analysis on the Mobil 1 Truck and SUV 5w40 oil to see how it is doing before any new effort.