OIL OIL LAB TESTING What does it all mean??

Yes. About $20-30 last time I did it.

The longer version is that I was sending the used oil samples to Blackstone for a number of years. At first I was doing it mostly to look for clues about engine internal condition. As I learned more I started using it to help evaluate whether I made good choices in selecting the oil. However every time I found something I liked, the next year it was no longer available in the same formulation!

Yes. It did help me spot a problem, but it wasn't because the lab spotted it. The iron was slowly increasing when it should have been decreasing. I already had known oiling issues on the new 340 which I had spotted by paying attention to the oil pressure and temperature. First was the pickup positioned a little high. But after that was fixed, I must have still had concerns. I'd have to look back and reconstruct the events, but the iron was one of the clues. So I pulled the rockers and found the wrong shaft had been installed resulting in light damage to bearing surfaces. I bought new shafts and had the cast iron rockers bushed.

Since then, I haven't have an oil analysis done. I might again, but don't consider it that great of a tool by itself. It's good when looking for trends and in combination with other information.

One thing I did notice is that for oil change intervals of 2,000 to 2,500 miles, the TBN was rarely used up. One time the TBN pretty much got used up was when I ran the Jeep well past its usual oil change interval AND had not topped it off regularly. Also, it can be useful in seeing what the actual viscosity is after use or abuse. (Remember the SAE wts are just a starting range, after shearing and heat cycles it can fall out of that range)

Let me know if this is what you were curious about, or some other aspect.