I would like to know, what is the purpose of certain heavy metals in lubricants, e.g. Zn, Ca, Mg, P... Is it important for the lube oil? Where does it come from?

Another thing, does different test methods (for metal analysis) affect the results?

Some of the common metals that appear in a typical lube oil (USED OIL) analysis (Engine oils) are
Element Probable source from engine
Aluminium Pistons & Bearings
Chromium Cylinder liners, piston rings Copper Bearings & coolers
Iron Crankshaft,Gears,Rings
Lead Bearings
Nickel Rings & Steel Compounds
Silver/Tin Bearings
Molybdenum Pistons Rings

Element Probable soursc Additive packages
Zinc/Phosphorus Antiwear additives
Sulphur Base oils & Additives
Mag & Barium Rust inhibitor packages
Silicon Antifiam packages
Calcium & Mg Detergency pacxkages
Boron Dispersants

The ICP Spectrophotometer can identify Elements in traces of part per million hence most of these elements show up. Ferrography is used when larger particles are prevalent ( or oil has been for longer periods), hence for the same used oil sample, different equipment may detect and give different values. In fact ferrography may not detect some of the elements which are in a few parts per million.

If you seek more details email me at hussam_adeni@yahoo.com.

M Hussam Adeni

But why i checked the Specification of one kind of Anti-foam, it indicated that Si: zero.

Are there some different kinds of Anti-foam additives for Lubricant oil?

Thanks for your hlep!

Kelly

Your question: What is the purpose..... Zinc and Phosphorous are used in oil formulations as anti-wear compounds. Moly is uses in some oils as anti-wear. Calcium and Magnesium are detergent/dispersants to keep the engine clean and avoid filter plugging and deposits.
Most other metals found in the analisis are wear metals unless you use leaded gasoline. Then lead - sometimes more than 1000 ppm - is coming from the gasoline.
If you can handle spanish, I have a lot of information and a table of where the wear particles prabably come from on
www.widman.biz

Rightly answered I guess
ZDDP- is the souce of ZInc is an antiwear.
Regards
Arupanjan