Is Zinc a "carbon promoter"?

[Speak2Mountain]

Read this: "Further to what has been said, the type of engine oil used and the fuel you choose to run the car on make a massive contribution to carbon build up."

"Older 'classic'oils, (especially the monogrades, but anything with an SAE rating of SF-CG or earlier) often have a high zinc content, and zinc is an unbelievably good carbon promoter. Just 6 parts per million in diesel fuel can quickly lead to coked up fuel injectors!"

 

[Kestas]

What does zinc in oil have to do with zinc in fuel?

 

[andyd]

Originally Posted By: Kestas
What does zinc in oil have to do with zinc in fuel?
coked rings? Just a wild guess.

 

[Eddie]

Do we have a link to an article that has some data? Might be interesting. Ed

 

[uart]

Originally Posted By: Eddie
Do we have a link to an article that has some data? Might be interesting. Ed

Good question. The only reference that I can find to the OPs quote is a guy called George saying it in a Norton motorcycle forum.

http://www.nortonownersclub.org/noc-chat/general/389181786

 

[SonofJoe]

I've never heard of ZDDP being a carbon promoter. I wonder if this is a case of 'guilt by association'?

If your engine's consuming oil (down the valve guides say) then it will deffo be a major contributor to piston deposits. If you analysed said deposits, you would definitely find Zinc there (as well as Phosphorus). If you were running very old spec oils, then you might find a lot more Zinc than say Calcium or Magnesium (from the Detergent). Also if we're talking old oils (all Group I, bugger all by way of additive) then the oil won't need much 'promoting' to turn to oxidised junk.

The link was for old Norton bikes (the ultimate in automotive hi-tech in 1961!) so all of the above seems plausible to me.

 

[CT8]

Everything that probably doesn't combust thoroughly leaves carbon deposits cause most everything is carbon based . Chem 101

 

[CT8]

Originally Posted By: SonofJoe
I've never heard of ZDDP being a carbon promoter. I wonder if this is a case of 'guilt by association'?

If your engine's consuming oil (down the valve guides say) then it will deffo be a major contributor to piston deposits. If you analysed said deposits, you would definitely find Zinc there (as well as Phosphorus). If you were running very old spec oils, then you might find a lot more Zinc than say Calcium or Magnesium (from the Detergent). Also if we're talking old oils (all Group I, bugger all by way of additive) then the oil won't need much 'promoting' to turn to oxidised junk.

The link was for old Norton bikes (the ultimate in automotive hi-tech in 1961!) so all of the above seems plausible to me.
If we are going back that far how about the leaded gas.