Got on it & BOOM

[Rick Parker]

patrickt:

Good article here:http://www.circletrack.com/enginetec...nts/index.html

By the way EOS is again available at GM dealers, the formula may not be the same though (???)

[patrickt]

Originally Posted by Rick Parker

patrickt:

Good article here:http://www.circletrack.com/enginetec...nts/index.html

By the way EOS is again available at GM dealers, the formula may not be the same thoiugh (???)

Good article, thanks. The new GM EOS still has quite the ZDDP, but the detergents have changed. I fear the new formulation is more directly targeted at engine break-in rather than extending the life, and zinc/phosphorous content, of your oil. I bought a case of EOS back before the switch so I'm still using the old stuff that did not have detergent levels this high; I should add that caveat to my posts recommending EOS. Of course, having too high of a detergent level defeats the purpose of the additives. I know in my archives I have a copy of the analysis of the old EOS, so after I wake up, have another two cups of coffee, and walk the dog, I'll see if I can find it and then edit this post to include it. Here's the analysis of the new stuff. Note the calcium level:

[will butterwort]

a bronze gear on ford distributor--older type--bronze gear sheared off in pretty cut pieces--shavings--drove car home from pigeon forge tennessee to ranburne alabama, 302, --pulled oilpan--the double hump kind--presto--there were the bronze gear shavings at bottom of oil pan in perfect round circle.Checked oil pickup screen close, cleaned pan, installed msd dist with iron gear new oil and fired her up.Ran great.Will-alabama

[patrickt]

Here's the old EOS. Note the increase in the detergent package. It has gone from roughly 8000ppm to almost 32,000ppm. A four fold incease; that is significant.





Search terms to help find this thread in the future: GM EOS, E.O.S. old versus new, ZDDP, Zinc content, Extended Oil Service, phosphorous, flat tappet wear

[vettestr]

Patrickt,
In reading your post you mention the 4 fold detergent package numbers in the NEW formula. Then said "Of course, having too high of a detergent level defeats the purpose of the additives." Are you thinking the amount of detergent in the new EOS negates the benefits or just that it it much higher than the Original?

[patrickt]

Originally Posted by vettestr

Patrickt,
... Are you thinking the amount of detergent in the new EOS negates the benefits or just that it is much higher than the Original?

I don't know if the increase in Ca now offsets the benefits of the increase in ZDDP. The literature suggests that an increase in calcium detergent (as opposed to Ca/Mg or Ca/Mg/Na detergents) increases wear. Likewise, the literature also suggests that "too high a detergent level" is not good for your engine. I don't know why GM had to change it to begin with, but evidently they did.