suggestions on oil weights

Discussion in 'Engine Topic' started by janis80z28, Jun 28, 2011.

  1. janis80z28

    janis80z28 Member

    Mar 8, 2006
    Chesterland, OH
    i have a 1985 rebuilt 350, from the block up. its now a 383 stroker. What weight oil do you recommend?

    it has 700 miles on the motor already.
  2. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

    Sep 20, 2004
    Southern Maryland
    do you know what the bearing clearances are? Assuming it has normal (1.5-2 thousandth) clearances I would just run 10W-30.
  3. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    Jun 22, 2003
    Endicott, NY
    10W30 synthetic.
  4. SupplySgt

    SupplySgt Veteran Member Lifetime Gold Member

    Jun 20, 2009
    Finally back home!!!
    Better know for sure that there are no cork gaskets. I would guess that there aren't but I would rather know for absolute sure. Synthetic is death to cork gaskets. That's the main reason I haven't started running synthetic in my 73. Once I am able to pull the motor and replace all the gaskets and everything I will start running synthetic. You did give the weight that I was gonna recommend though.
  5. janis80z28

    janis80z28 Member

    Mar 8, 2006
    Chesterland, OH
    I did do a bit more digging. 10w 30 looks like the one. BUT I see people saying to add ZDDP. What do you guys think of adding this stuff to the oil?

    not doing synthetic for now.
  6. hhott71

    hhott71 Veteran Member Lifetime Gold Member

    Mar 30, 2001
    Joplin Mo. 64801
    Whatever gives you atleast 20lbs of pressure at idle, in gear with a hot engine.

    Could be 5w-20

    could be 20w-50

    Start with 10w-30 and see...

    Your 1500 rpm and up pressure will probably be 45 lbs and up on any of the oils.
  7. NYH1

    NYH1 Veteran Member

    Feb 27, 2010
    Central New Yorkistan
    I agree. I'm getting 18 to 20 psi. at warm idle with both 5W-30 or 10W-30. The main difference between the two is at cold start up. With 5W-30 my oil pressure is right at 60 psi. and with 10W-30 it's 65 psi. My oil pressure drops a little quicker with 5W-30 as my engine gets up to operating temperature. Once it's up to operating temperature, they're the same.

    At cruising speeds my oil pressure is anywhere between 40 and 60 psi. depending on my engine speed.
  8. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    Jun 22, 2003
    Endicott, NY
    Synthetic is murder on cork gaskets? I ran Mobil 1 in my '79 Olds with a 300 hp 350 SBC for 86K miles and it never leaked a drop of oil out the valve covers.
  9. ProStreet383

    ProStreet383 Veteran Member

    May 23, 2007

    It is just an old wives tail. The real proven truth is that dino oil gums up and sludges up much easier than synthetic. What this does to an engine that is getting older and getting miles on it is form deposits around already deteriorating gaskets and keeps them from leaking. A switch to synthetic starts cleaning up those deposits and suddenly a leak starts and the synthetic gets the blame. Synthetic oil itself does not deteriorate any type of gasket material.

    P.S. To anybody interested I get dealer pricing on all amsoil products. I am not a dealer. I have a business account with them for my lawn service. I use amsoil in everything because I get a good price on it and it truly is great products. If anybody wants I can get you dealer pricing on anything amsoil sells. Just PM me. That Z-Rod oil i posted above in over $9 a quart street price. It is about $7 my price which is still high but it is a "REAL" synthetic Group 4 base stock.
    Last edited: Jun 28, 2011

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