Interesting oil test blog

terraplane8terraplane8 Posts: 604Senior Contributor

He says that high zinc oils are worthless in terms of protecting flat tappet engines, very interesting read.


  • ratlee2ratlee2 Posts: 371Expert Adviser
    There probably is some truth to that.  My daily driver is a 2001 Jeep Wrangler with 180K on the odometer.  The Jeep 4.0L straight six came from the factory with a flat tappet cam until 2006 when Jeep went to a different engine and that was 12 years after they started phasing out the zinc in oil.  If you look around while driving, there are still a lot of wranglers from that era still on the road.  Recent videos are pointing to cam failures being caused by poor cam/lifter machining and hardening processes.
  • terraplane8terraplane8 Posts: 604Senior Contributor
    Here's a comment that is interesting for the older engines:


    From Blog reader M.P. on December 5th, 2022:

    540 Rat-

    Many thanks for the fact-based work and testing you’re doing.

    I’ve road raced a vintage 4 cylinder car for 10+ years, rebuilding the motor every 2 years or so.

    With the latest motor, we utilized your test results and ran the motor from new with 5w30 Quaker State Full Synthetic, API SP that you highly recommend. Inspection after a recent teardown revealed cam lobes, followers and cylinder liners in FANTASTIC condition. Visibly and measurably less wear that we’ve experienced in the past with high viscosity “race oils”.

    Thanks again- you are a unique human being and a blessing to those in the motorsports community willing to learn.

    M. P.

    Hi M.

    You are welcome. Thank you very much for the kind words. It’s nice to hear appreciation like that.

    And thanks for the terrific feedback on your experience. It’s great to read that you have had amazing success just like many, many of my other Blog readers have had, from making use of my Engineering Test Data.

    The source of the incredible results you and my other readers have benefitted from, can ONLY be found here in my Blog. All that “Real World” experience EXACTLY MATCHES what my Test Data has “Always Predicted”. And it specifically backs-up my recent Tech Article #75 on the CURE for flat tappet cam lobe failures.

    That’s why I do all this. Because the Automotive World needs someplace to go that actually provides Engineering FACTS.

    Take care,

    540 RAT

  • tigermothtigermoth Posts: 558Expert Adviser
    The whole “ZDDP” debate seems to have started from the failing original Crane Cam. Rather than accept blame for their inferior work and products they shifted the blame to the oil formulation. The internet, oil additive salesmen and owners with more time than grime on their hands did the rest. Tradesmen who actually work on cars, theirs and others, as reflected in professional trade magazines, did not promote this as an “issue”. 

    Regards, Tom
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