Three high-ZDDP 40-weights

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Note: I will post each of these in its own thread with the oil type and date in the title so that it will be easier to find with the site's search engine... but I also wanted to post all three in a single thread for comparison's sake. The oils are: Rotella T6 CK-4 5w40, Redline 0w40, Royal Purple HPS 10w40. This is something I really did for other forums more than BITOG, because the current misinformation out in flat-tappet land is "Rotella changed! Its no good anymore! Its not for gasoline engines! They lowered the Zink " <- yes, that's how most of these goobers spell it). Now I have a VOA to prove that the ZDDP dose didn't change when they dropped the PCMO SN approval and went to only Diesel CK-4 approval. The other two are a couple of common alternatives that I had on hand- Royal Purple HPS 10w40, and Redline 0w40 (which I use in my SRT-8, not my vintage cars, though now that I see the results I certainly could use it!). Royal Purple shows a low flashpoint, which to my way of thinking agrees with its habitually mediocre NOACK results. I've used it in my 1960's flat-tappet 440 Magnum v8s with good UOA numbers, but it does increase the consumption a bit. Given everything in these three VOAs, I really doubt I'll spend money on purple bottles anymore... at least until/if they really DO revise Rotella T6 and cut down the ZDDP.

ROTELLA T6-190920.jpg


Colorado, USA
Good info, thanks! All very good higher zinc oils. Where does Blackstone get different "should be" values for these oils when they all are 40 weight on the top end? Doesn't make a freakin' bit of sense and they've tried to explain it away to me when I have had UOA's of synthetic 10w40 with my motorcycle. They said because my sample oil starts as a lower 40 weight as per the manufacturer specs, the "should be" values shift. In this case it was Mobil 1 10w40 4T. Even though it sheared out of grade a small amount by industry specs, they said it remained in grade relative to the amount it dropped from where it had started.