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HT4100 4.1, 4.5, 4.9 Discussion, Ht4100 in Cadillac Engine Discussion; I am thinking of using Royal Purple 20W40 (for diesel and Gasoline Engines), in my HT4100 - 87 Eldorado. Any ...
  1. #1
    globetrotter8888 is offline Cadillac Owners Member
    Join Date
    Jan 2006


    I am thinking of using Royal Purple 20W40 (for diesel and Gasoline Engines), in my HT4100 - 87 Eldorado.

    Any comments?


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  3. #2
    noahsdad's Avatar
    noahsdad is offline Cadillac Owners Connoisseur
    Automobile(s): '87 SDV
    Join Date
    Jun 2005

    Re: Ht4100

    Stand back. Oil questions on this forum = burning match + puddle of gasoline. Lots of strong opinions.

    But here goes. I'm not famiilar enough with Royal Purple to comment on it, however I can tell you this: I switched my HT-4100 '87 DeVille to Amsoil synthetic 10W-30 ASM two years ago, and send oil samples to Blackstone Laboratories for analysis at each change.

    I change my oil twice a year, usually 3500 to 4 thousand mile intervals. The wear metals content is now 62% lower than the universal averages for engines of this type. I did get a small bump in aluminum and iron on the last test, but it may be because I took the sample from the filter instead of the drain stream. The TBN of the Amsoil was very high, almost new, even after 7 months in the crankcase. The oil lab has recommended I extend my drain interval to 4500 miles.

    This isn't a pitch for Amsoil. I don't sell it, or cheerlead for them (at least not here). Just my experience. My point is, if you want to experiment with a product, don't be afraid - just follow Ronald Reagan's advice: Trust but verify.

  4. #3
    C66 Racing's Avatar
    C66 Racing is offline Cadillac Owners Enthusiast
    Automobile(s): 06 CTS-V (sold)
    Join Date
    Oct 2006
    King George, VA

    Re: Ht4100

    Here's the oil to which Noahsdad is referring:
    AMSOIL SAE Synthetic 10w30

    And this is an example of what he's learned from his used oil analysis (this one from a customer of mine with a Corvette):
    Corvette C5 Used Oil Analysis Report – AMSOIL SAE Synthetic 10w30

  5. #4
    peteski is offline Cadillac Owners Enthusiast
    Automobile(s): 85 Eldo Biarritz
    Join Date
    Dec 2003
    Northeast USA

    Re: Ht4100

    Here we go again....

    I recommend "Sliski 45W50". Oil manufactured from a rare Polish crude found only in a small area in the Tatra mountain range. 100% natural and organically mined. No artificial (synthetic) indgredients


  6. #5
    globetrotter8888 is offline Cadillac Owners Member
    Join Date
    Jan 2006
    Thread Starter

    Re: Ht4100

    Thanks for the info. I got my answer


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