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  1. R

    Blackstone, diesel UOA, and soot.

    I've used Blackstone for UOA on a race car for years, but now I want to do a UOA on my Ram Ecodiesel. My understanding is that I need to be aware of soot (ash?) levels in the UOA to judge when the oil is done. Blackstone doesn't seem to provide a # for soot in their analysis, so maybe I need to...
  2. R

    Explain loss of viscosity pls

    I race a late 80's BMW. Lately I've been using Brad Penn 20W50, mostly because Navarro at LNEngineering and the Pelican forums likes it. BP 20W50 has a 100deg Visc of 20.1, IIRC. Before that I was using Valvoline VR-1 20W50 Conventional which has a 100deg Visc of 22 I think. That was an earlier...
  3. R

    Rule of thumb for bearing clearance HTHS or Visc?

    Is there a rule of thumb for this? Something that relates tight bearings like .0012" to an ideal range HTHS #'s, or Visc in 100deg cST? Then .0018", and .0025" to the same? In my case the application is an '87 BMW race car. Engine is unmodified.
  4. R

    Consequences to reducing relief valve pressure?

    What happens if I put on an oil filter with a relief valve pressure of 12-15psi, when the OEM filter has a relief valve pressure of 25-35psi? I'm not even sure if I understand what the relief valve does. My car has a hot idle pressure of ~10psi. If there is some valve in the oil filter that...
  5. R

    10psi/1000rpm rule and running lower viscosity oil

    The AEHaas Motor Oil articles on this site emphasise using 10psi/1000rpm as the general rule for selecting oil viscosity. How good of a rule is this? BMW oil has a cST of 12.2. It is 10W30 or 10W40. One of the BMW recommended oils is Mobil1 10W40 which has a cST of 11.5 or thereabouts if I...
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