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Thread: What Oil do you use for the P38!!

  1. #71
    Join Date
    Sep 2012
    Location
    Perth Australia
    Posts
    282
    I had been using Valvoline full syn 5-40 but it rattles its lifters off for 3 seconds most times when I start it.

    But saying that it generally only gets started 3-4 days so plenty of time for the lifters to bleed out.

    I've just changed the oil and filter and now trying 15-40, it's amsoil fully syn that I've had sitting around.

  2. #72
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    138
    I have become a bit obsessive in researching this subject However, for those who care, I've found this extremely large article from a guy who seems a bit full of himself and his methods but the science behind it does seem very solid.

    https://540ratblog.wordpress.com/

    very VERY long story, fairly short: ZDDP or zinc in and by itself is a myth. HTHS is also not the end all be all number to look for and synthetic is by no means better then conventional. Some additives work, but stay away from zinc additives since in all tests they severely reduced wear protection.

    The only unanswered question that the author only touches on briefly is thickness of the oil vs. bearing clearance. ie engine build tolerances vs viscosity. I intend to ask the good man about our rover (buick) V8's in this regard but it does seem that modern oil should do just as well for our flat tappet beasts as we expect from old school oil, better even in a lot of cases.

    I know, it's TL;DR that article but if you have the time and the patience to read past the mans repetitiveness, this is a good read!

    -P


  3. #73
    Join Date
    Oct 2017
    Location
    Tasmania
    Posts
    9
    Hi Prelude,

    Just out of interest, did you do that testing of oils that you spoke about, and if so what were the results...... Very interested to know what you found.

    Cheers Rob

  4. #74
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    138
    Hi Rob

    I have made my trip up and down to the north cape. I drove down to my dads place first (who lives on the upper edge of the lower 1/3 of sweden (200k's north of sotckholm) and at that point my car needed an oil change. I swapped the 20w50 for BP visco 7000 5w30 for the cold temperatures. I can't say that starting with the thinner oil was easier or that fuel consumption was better. The conditions in which I was driving simply did not allow for me to notice that. I drove that oil all the way back home where I changed it back to 20w50 again (valvoline VR1). Since the engine was barely broken in and holy used a sort of grease to help prime the oil pump and such the oil was still black as tar (the grease having mixed with the oil) and testing that batch was simply out of the question. On the german autobahn, making good time and in much higher temperatures than up north I did notice the engine to be much noisier with the thinner oil.

    Since then, unfortunatly, I have not used the P38 a whole lot. I did change the oil once and I finally got to a point where all the grease from the rebuild had been flushed out. The last oil change was a normal colour. So, I intend to send in my sample after the next oil change which should be the coming month.

    Long story short: I will get my first sample soon-ish

    Cheers,
    -P

  5. #75
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    138
    a very late PS

    I read my last post about and this line jumped out:

    very VERY long story, fairly short: ZDDP or zinc in and by itself is a myth. HTHS is also not the end all be all number to look for and synthetic is by no means better then conventional. Some additives work, but stay away from zinc additives since in all tests they severely reduced wear protection.
    What I meant here is additives that come in a small bottle, to be added to the engine after you have replaced the oil. Additives that come IN the package itself, thus come premixed in the oil, are a completely different story.

    -P

  6. #76
    Join Date
    Oct 2017
    Location
    Tasmania
    Posts
    9
    Quote Originally Posted by prelude View Post
    Hi Rob

    I have made my trip up and down to the north cape. I drove down to my dads place first (who lives on the upper edge of the lower 1/3 of sweden (200k's north of sotckholm) and at that point my car needed an oil change. I swapped the 20w50 for BP visco 7000 5w30 for the cold temperatures. I can't say that starting with the thinner oil was easier or that fuel consumption was better. The conditions in which I was driving simply did not allow for me to notice that. I drove that oil all the way back home where I changed it back to 20w50 again (valvoline VR1). Since the engine was barely broken in and holy used a sort of grease to help prime the oil pump and such the oil was still black as tar (the grease having mixed with the oil) and testing that batch was simply out of the question. On the german autobahn, making good time and in much higher temperatures than up north I did notice the engine to be much noisier with the thinner oil.

    Since then, unfortunatly, I have not used the P38 a whole lot. I did change the oil once and I finally got to a point where all the grease from the rebuild had been flushed out. The last oil change was a normal colour. So, I intend to send in my sample after the next oil change which should be the coming month.

    Long story short: I will get my first sample soon-ish

    Cheers,
    -P
    Hi P,

    Thanks for the update, Glad all has gone well so far 👍
    Keep me/everyone updated with the test when you get it back ..... Really APPRECIATE it.
    Cheers Rob

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