Cat damage

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2,724
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Herndon, Virginia
Ok, so ZDDP (according to lots of parties) over time, will wreck the cat, 02 sensor. Now, if you want an additive to carry the oil through times of thin/no film, Moly must be the answer to ZDDP, right? Does Moly hurt cats and 02 sensors? If not, and Moly is the answer to SM oil-boosting, where do you get an additive with JUST moly, and no ZDDP? Our favorite moly-boost is, I suppose, VSOT, but that also has a high ZDDP count. Finally, what about calcium and boron? Do they hurt cats and sensors? Thanks!
 
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882
Location
North Carolina
If an engine consumes oil at an "elevated" rate then the cat killing concerns with ZDDP are well founded. If however the engine uses only a tiny amount of oil, maybe no visible useage over a 6K OCI: then a huge dose of zinc in the oil shouldn't matter should it? I believe that the recent zinc reductions are at least partially done to address those engines that "consume" I am not aware of any evidence one way or the other regarding moly killing cats. Rickey.
 
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11,211
Location
Bad Axe, MI
^^^ i agree, IMO if your not using any oil i wouldn't worry about it, i've been using SLOB for awhile now and it's loaded with ZDDP i've had no problems.
 

toocrazy2yoo

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Herndon, Virginia
Well, 427, I get the concern of the Cat-Manufacturers and researchers that did those PDF's, but is the anti-wear achieved by ZDDP formulations WORTH the cat damage? By removing ZDDP, are we reducing the life of the engine, a major component, in order to save the catalytic converter, a relatively minor component price-wise? And to whose benefit is it to remove ZDDP from oil? Trading off higher engine wear to save the cat seems like quite a contradicton.
 

toocrazy2yoo

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Herndon, Virginia
Well, to be fair to the authors of said PDFs, for all I know, at the level of a 2005 Hyundai 1.6L DOHC Four, I simply don't NEED ZDDP, Moly, or any of it. The car did spec SL which had a lot more additive than SM. Then, with API SM, and ILSAC GF4, the oil is supposed to be so good without the additive, I really feel no compulsion to put the stuff in anyway. However, for my car, or for older cars, flat tappets and the like, are we trading greater engine wear under API SM for a clean catalyst?
 
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7,409
Location
Austin, TX
Quote:
If an engine consumes oil at an "elevated" rate then the cat killing concerns with ZDDP are well founded. If however the engine uses only a tiny amount of oil, maybe no visible useage over a 6K OCI: then a huge dose of zinc in the oil shouldn't matter should it? I believe that the recent zinc reductions are at least partially done to address those engines that "consume" I am not aware of any evidence one way or the other regarding moly killing cats. Rickey.
Wrong. Some of the volatile components of ZDDP make it to the Cat whether you use any oil or not. Some reading on Cat Poisoning: http://repairnet.aircare.ca/documentation/newsletterpdfs/2005-1.pdf http://herkules.oulu.fi/isbn9514269543/isbn9514269543.pdf http://www.savantgroup.com/ASTMSym04-PEI.pdf http://www.swri.org/dasl/n-tcd/dasl_n-tcdb4.pdf http://www.eere.energy.gov/afdc/pdfs/32842.pdf http://www.swri.edu/3pubs/ttoday/Winter04/Focas.htm
 
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562
Location
Austin, TX
Have used HDEO Shell Rotella Syn, rated SL, in an oil burning engine (1 qt per 3K) since 65K. Just passed emissions at 101K miles on engine with original cats and O2 sensors. Most oils were SL rated until pretty recently. The EPA mandates exhaust systems last for 100K (nice to have stainless pipes standard huh). Depending on the car, fuel, etc., this might require SM oil.
 
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1,577
Location
Surrey, BC
My 94 Metro burns a quart of oil every, oh, 500 miles or so. It burned less in the past, but still a quart per 1000-2000 miles for the last few years. I passed emissions a few months ago with stock cat and O2, 110k on the odometer. Admittedly I squeaked through on HC, but CO and NOx looked great. If a 12-year-old cat that's seen a few dozen quarts of SJ/SL oil go through it can pass testing, I wouldn't worry too much about using SM.
 
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5,785
Location
Dixie
Without zinc and phosphorus, your valvetrain components would not last very long. MODTC suppliments the ZDDP in modern engine oils, but does not totally replace it any more than boron does. ZDDP is also highly effective in minimizing oil oxidation/thickening, so it's a multifunctional add. TS
 
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7,409
Location
Austin, TX
Quote:
Without zinc and phosphorus, your valvetrain components would not last very long. MODTC suppliments the ZDDP in modern engine oils, but does not totally replace it any more than boron does. ZDDP is also highly effective in minimizing oil oxidation/thickening, so it's a multifunctional add.
Yeah, but no one has totally eliminated ZDDP in there formulations yet. And valvetrain designs have changed considerably over the past twenty years. For example, GM has virtually eliminated flat tappets since 1986. And bucket lifters in OHC designs don't see anywhere near the load as lifters in pushrod designs. All Hondas are rollerized OHCs. And timing chains see a lot less load with OHC designs and G-rotor oil pumps driven by the crankshaft. Worrying about ZDDP levels in modern engines for normal OCIs is Chicken Little type worrying.
 
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1,396
Location
Sarasota, Florida
For those who are concerned about the new oils having reduced ZDP, read: How Much ZDP is Enough, Olree and McMillan (of GM). Levels above 0.03 do not provide any more engine wear protection than higher levels. If, on the other hand, levels are below 0.03 then wear does begin to increase as the level decreases. aehaas
 

toocrazy2yoo

Thread starter
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2,724
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Herndon, Virginia
Thanks, Andy, I found that link, but didn't know if it was the same. I'm curious, but not THAT curious! Heck, I could buy 5 bottles of SLOB for the cost of the download!
 
Messages
882
Location
North Carolina
Quote:
Quote:
If an engine consumes oil at an "elevated" rate then the cat killing concerns with ZDDP are well founded. If however the engine uses only a tiny amount of oil, maybe no visible useage over a 6K OCI: then a huge dose of zinc in the oil shouldn't matter should it? I believe that the recent zinc reductions are at least partially done to address those engines that "consume" I am not aware of any evidence one way or the other regarding moly killing cats. Rickey.
Wrong. Some of the volatile components of ZDDP make it to the Cat whether you use any oil or not. Some reading on Cat Poisoning: http://repairnet.aircare.ca/documentation/newsletterpdfs/2005-1.pdf http://herkules.oulu.fi/isbn9514269543/isbn9514269543.pdf http://www.savantgroup.com/ASTMSym04-PEI.pdf http://www.swri.org/dasl/n-tcd/dasl_n-tcdb4.pdf http://www.eere.energy.gov/afdc/pdfs/32842.pdf http://www.swri.edu/3pubs/ttoday/Winter04/Focas.htm
From the savantgroup PDF page 4 "In a further analysis of the IOM data, it was unexpectedly found that phosphorus volatility also unrelated to phosphorus concentration in fresh oil [19,20] as shown in figure 4." Very intresting reading Thanks for the links 427. I was unaware of this. In some of the documents a linkage is mentioned regarding the oils NOACK volatility and ZDDP(Phosphorus) contamination of the Cat. I stll maintain that a non oil burner will poison the Cat less. Rickey.
 
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