Originally Posted By: Chris142
Originally Posted By: RiceCake
^ Probably exactly what you're looking for in every possible way.
Funny how low it is in ZDDP. Some people would be calling that oil terrible by that yardstick, lol.
zddp damage the silver bearingss?
Multiple different white metal formulations have been used, and many of them don't contain lead, they contain a lot of silver, and often copper (cow of a metal to dissolve in a white metal blend)...early lead based bearings had high impregnation (particles could jam into the metals, keeping them within the hydrodynamic film, and away from rotating components, and was a desirable feature)...however, as projected bearing loads rose (load on bearing area), the lead based stuff deformed under the hydrostatic, and hydrodynamic pressures, and they made the materials stiffer/stronger by less lead, and more antimony, zilver, copper etc.
However, zinc messes with either silver plated stuff, or silver bearing alloys, and leads to the bearing metal breaking up (crumbling, as alloys harden with varying concentrations of metals in the early forming dendrites, versus the stuff that's left to harden at the grain boundaries).
Something we have to be careful of in industry, as even purely hydrostatic bearings that don't need a lot of FM characteristics, the amount of zinc in a typical hydraulic oil can cause failure after a few 10s of thousands of hours. (Using STP as a maintenance lube on turbine bearings is bad news, and was once common practice (Lucas is better, being add free)).
to the OP, you won't find any "HO" 20 weights in the application that you are after, most of these are straight 30s, 40s, and 50s, as cold starts aren't activities that occur regularly in these engines in their original applications...and in museums, they aren't that cold, nor do they see serious loads.
You are going likely to only find straight 40s, like Delo 6170CFO or BP (note the 20W-40 available).
http://www.bp.com/business/sectiongenericarticle.do?categoryId=9038524&contentId=7070712