71T oil analysis results - feedback

smiles11 · smiles11's Garage

Received my oil analysis back on my 1971 911T. Report shows a high amount of lead & above average amount of copper. I do run a few gallons of 110 leaded fuel at every fill-up.

Could <0.5% fuel contamination spike the lead value that much?

The copper is a mystery however.

The engine was rebuilt less than 5,000 miles ago.

Engine rebuild is on the OP of my RL thread:

https://rennlist.com/forums/911-foru...to-me-71t.html

Gspin · 06-11-2025, 02:17 PM

The question that I would have for Blackstone is if the fuel burns off does the lead still remain in the oil? Also, have you had the oil filter taken apart and analyzed? I would run the new oil for 1,000 miles and send back to see if the lead was part of any break in process too. Good luck!

smiles11 · smiles11's Garage

Quote:

Originally Posted by Gspin

The question that I would have for Blackstone is if the fuel burns off does the lead still remain in the oil? Also, have you had the oil filter taken apart and analyzed? I would run the new oil for 1,000 miles and send back to see if the lead was part of any break in process too. Good luck!

I have not had the oil filter analyzed but will likely send that in on the next oil evaluation. I did ask about the fuel contamination being <0.5% & still having a high reading of lead. I assumed there would be way more fuel contamination if there was a high reading of lead.

I did flood the engine a couple times prior to the oil change. So that probably didn't help lol

stownsen914 · 06-11-2025, 02:56 PM

Re: fuel contamination, keep in mind that fuel evaporates, but lead stays behind. It may be expected that the lead is proportionately higher % than the fuel.

stownsen914 · 06-11-2025, 03:02 PM

I have some Blackstone reports from a few years ago on my race engine that runs leaded race fuel, lemme take a look and see what the lead numbers are. Feel free to PM if I forget (which is likely).

Also, re: copper in the oil I had a similar result a few years ago. After seeing it on two different engines, I sent a sample of unused oil for analysis and it turned out the oil stock had high copper in it. Even the Blackstone guys were surprised. It was some older leftover Kendall. I stopped using it after that.

smiles11 · smiles11's Garage

Here is the response I received from a Blackstone Labs analyst in regards to lead & copper:

Yes, leaded fuel is the most likely source for lead in your fuel, though it could also be masking any lead the bearings might be making.

It's normal for leaded fuel to put lead into the oil without any actual fuel being present. All engines blow-by to some extent. Under normal conditions, any fuel that blows by the rings into the crank case will be vaporized by the hot oil and exit as gas via the crank case ventilator, leaving just the lead behind. When we find liquid fuel in the oil, it's usually the result of the oil not getting hot enough, as with a short startup/idling, or a fuel system problem that's just dumping more fuel into the oil than it can boil off.

Thanks for mentioning the rebuild. With that in mind, the elevated copper in your oil is likely just left over break-in metal, so just look for it to improve next time as a sing bronze parts are wearing like they should. We'll get an amended report to you with that information shortly.

Hope that helps. Let me know if you have any other questions

Best regards
Ethan Webster
Analyst