Zinc in Engine Oil

[Falcon_LS]

An interesting bit of reading I came across, on an Australian oil company's website, and thought I'd share:

Quote:
There is a growing trend to use heavy duty diesel engine oils in older, “classic” engines due to apparently higher zinc levels.

However, changes to heavy duty engine oil specifications have meant a decrease in zinc levels and in some cases, these are less than what some engine builders desire – but more than what others require. This is apparent with ACEA E6 type oils and to a lesser extent, API CJ-4 oils.

Also in the background is the fact that for many years, some owners of classic cars, club experts and mechanics have always been against diesel engine oils because they have too much detergent which will clean out and maybe damage engines. This is not unique to any one country. So there is some contradiction here as detergent is suddenly not a factor. In reality, it has not been a factor, especially in a reconditioned engine once run in. (Note: high detergency may cause bore glazing if the engine is not loaded enough during the run in phase as the oil is “too good”.)

Remember the zinc maximum (actually phosphorus) for API SM (ILSAC GF-4) products only applies to SAE 0W-20, 0W-30, 5W-20, 5w30 and 10w30 viscosity grades. Other SAE grades do not need to comply. Incidentally, ILSAC GF-5, due in a couple of years will drop phosphorus maximums to 700ppm (or about 770ppm of zinc from ZDDP).


Source

 

[StevieC]

Falcon_LS:

Thanks for posting...

I always read the MSDS to see whats in an oil and use used oil analysis to determine if the oil is the right fit for the application.

 

[Pablo]

Sounds like Penrite reads BITOG. This has been said many times here. I have said it at least 3-4 times in the last few months.

 

[mechtech2]

High detergency causes bore glazing because the oil is too good?
I think that is silly.
What is a glazed bore? Shiny with no cross hatch.

 

[StevieC]

Originally Posted By: mechtech2
High detergency causes bore glazing because the oil is too good?
I think that is silly.
What is a glazed bore? Shiny with no cross hatch.


As someone who has done engine jobs I'm ROFL! No such thing as too much detergency.

 

[Gary Allan]

there is one more argument for using high power loading for short periods (to avoid excessive heat) during the break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break in procedures.

http://www.ntnoa.org/enginebreakin.htm

There are other references out there. It's not a common occurrence these days. The motor cycle crowd appears to be the most vulnerable.