>The problem is that the government and auto manufacturers have pressured oil companies into removing most of >the zinc (which is used as a high pressure resistant lube) from oil. The reason is an oil burner car will coat the >inside of a catalytic converter with zinc and eventually render it useless. According to the Shell Engineer who gave the seminar it's the O2 sensor that's the main problem and is Phosphorous (which is included as part of the Zinc package) not Zinc that is causing it. Phosphorous burns leaving an ash coating on the O2 sensor. It's not much but over time it causes the O2 sensor to get "lazy" reading the O2 thus causing the engine to run richer which in turn increases emissions. THAT'S why the government got involved. >So far, as long as a flat tappet (standard lifter, no rollers) cam has been broken in with a high pressure additive >in the oil, there's still enough zinc in regular oil to lube it -- at least in a STOCK engine. The people who've been >experiencing problems the most are those with higher pressure valve springs (performance engines). There may >be increased wear on stock engines, but the zinc reduction hasn't been in affect long enough to really tell. That USED to be true but the Shell guy said they are now seeing stock OHV motors experiencing problems too. The engines with higher spring pressure started experiencing problems first. >A zinc supplement in the break-in oil seems to be the short term answer. I'm not sure if running a higher zinc oil >is really necessary after break-in, but it shouldn't be. I disagree. I think a high zinc oil plus additive is necessary for break-in and then the Zinc oil only (no additive) for the duration of the life of the motor. Why take a chance on wiping a cam?? What is "low Zinc" oil on the shelf? Look for the circle with the "API Certified for gasoline engines" in it. This is a LOW ZINC oil and should be used in roller engines only (according to the Shell Engineer). Low Zinc oil will be approx 600- 800 or less, some MUCH less. FILTERS Even filters that say they are "full flow" do not flow ALL the oil through them ALL the time. That is the reason for the OIL filter BY-PASS valve. Do you really think you can push all the oil a motor pumps through the filter when it's 0' outside?? No way, that's what your Oil filter by pass valve is for!! It also kicks in when your filter starts getting restricted with dirt. Better your engine gets dirty oil than NONE at all! MOST modern oil filtration systems have a filter by pass either in the block or the filter itself. YOU SHOULD NOT REMOVE THE BY PASS VALVE!!!! Oh you can get away with it sometimes but I don't know WHY you would want to starve your engine for oil. I have seen racers do this thinking it's some kind of "high performance trick". I don't think they truly understand why it's there and what it does. From WIX,,, The Filter By-Pass Valve If a WIX full-flow filter becomes "clogged", or excessively restrictive to oil flow, the filter by-pass valve ensures continued engine lubrication by allowing the oil to by-pass the filter. Some vehicle manufacturers have the by-pass valve built into the oil filter mounting unit (located on the engine). Other vehicle manufacturers require full-flow filters have the by-pass valve built into the filter itself. All Wix oil filter types recommended for these particular applications include the by-pass valve assembly in the filter. By-pass Valve Assembly -- spring loaded valve assembly that allows oil to by-pass the element under high-differential pressure conditions such as cold oil and/or excessively contaminated media. This allows lubrication of the engine, but without full-flow filtration But HEY,,, that's just ME!!! Bruce Hevner -------------- next part -------------- A non-text attachment was scrubbed... Name: winmail.dat Type: application/ms-tnef Size: 18889 bytes Desc: not available Url : http://splatter.wps.com/pipermail/amc-list/attachments/20080315/992efade/attachment.bin _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list