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s_morrison57 s_morrison57 is offline
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Join Date: Jan 2009
Location: Vancouver B.C. Canada
Posts: 2,083
Question More oil questions, ZDDP

I read an interesting thread on the 996 site about oil and the flow rates when cold or first start up in the morning. It basically said that no oil provides proper lubrication when cold, 75* F outside temp, even 0W-XX synthetic doesn't flow enough. Flow = lubrication, pressure does not = lubrication. This article was for water cooled engines but it's made me re-think the oil that I'm using in the 87 930 (all my cars for that matter). Presently I use Swepco 15W-40 and I'm thinking of sticking to the dino oil because of the high ZDDP count but going to a 0W-30. The ZDDP count in the Swepco is high (that's why I use this oil instead of synthetic) and I've often wondered what the ZDDP actually does and if a switch to a synthetic blend, 0W-30 with less ZDDP will really make that much of a difference on long term engine wear? What other things would be effected by a lower ZDDP count? Does synthetic oil somehow cover for the lower ZDDP count? The article made a lot of sense, stuff like the major wear on your engine is at cold start up and that the first number in a blended oil is how the oil acts, it's ability to flow, on cold start up. The numbers for flow on cold start up between 0W-30 & 10W-30 are huge, so much so that I'll never put anything other than a 0W-XX oil in any of my cars. Flowing oil is measured in centiStokes, cS, and your engine and oil are designed to have a 10cS flow at 212*F. At 75*F 10W-30 has a flow of 100cS, 0W-30 has a flow of 40cS but both flow @ 10cS when @ operating temp., by comparison a straight 30W oil has a flow of 250cS @ 75*F but still has a flow of 10cS @ 212*F. That's why I'm switchin to a zero blend oil and I'd prefer a synthetic oil but the ZDDP has me confused, can any body set me straight on this.
Finn
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Old 05-25-2013, 08:04 PM
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