Oops look what I just ran across on the TDI forum......
Here are the two most recent oil analysis from our 1996 Passat TDI wagon which is pretty much stock. Based upon the report back from OA, it looks like this PC Duron (GROUP III blend) 5W 40 has a long ways to go.
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now, this comment followed from a very, IMO, respected amsoil rep about this analysis....
The one thing that stands out is that chrome wear is fairly high in both these samples. You are running the equivalent of 6-7 ppm/10k miles, whereas I'd typically see 2-4 ppm/10k miles. I have no idea why this would be occurring, since the soot levels are quite low in both tests? The only thing I could suggest is that the prior maintenance practices on this engine weren't that good and you have some carbon buildup in the ring grooves. This could be the result of using a non-diesel rated oil or going too long between changes. It could also be the result of using poor quality diesel fuel for an extended time. At this point, there is no effect on cylinder (iron) wear, but it's something to keep an eye on.
Cleveland Tech Center uses a different ASTM test method for TBN than did OAI, so the results aren't directly comparable. Using the CTC test protocol (ASTM D-4739), I'd feel comfortable going down to a TBN of 4.0 as the allowable limit. You can see the reason for the TBN difference in these two formulations. Both use about the same amount of calcium, but Delvac 1 adds approx 500 ppm of magnesium as an alkaline, detergent/dispersant additive ....
Based on this data, I don't see a problem running 10k changes with either of these oils in this particular motor
[ May 13, 2003, 06:19 PM: Message edited by: BOBISTHEOILGUY ]