Huh. So not only does it depend on who you talk to out in general, it depends on who you talk to in the industry.
"Sudden temp changes" would be bringing it inside from outside, or vice versa. It wouldn't be sitting on a shelf in the garage. IIRC their concern was condensation; no mention was made of waxes.
Quote:
"Regarding cool whether gel formation, a small except from SAE j300 1999:
4. Because engine pumping, cranking and starting are all important at low temperatures the selection of an oil for winter operation should consider both the viscosity required for oil flow as well as cranking and starting, at the lowest expected ambient temperature.
Pumping viscosity is a measure of an oils ability to flow...during the initial stages of operation. Test in ASTM D 4684. ....samples are tested after a slow cool cycle. This cycle has predicted as failures several SAE 10W-30 and 10W-40 oils which are known to have suffered pumping failures in the field after short-term (2 days or less) cooling. These field failures are believed to be the result of the oil forming gel structures that result in excessive yield stress and viscosity of the engine oil...
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Translation: engines need oil thinner than 10W-x when it gets cold enough. That is why we have 5W and 0W.
Quote:
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A.2.1...After preliminary warming, the sample is subjected to a controlled temperature/time cycle over 5 1/2 to 7 days. The cycle reproduces ...instability or reversion which has occurred during storage of oils in moderately cold cyclic conditions. Recent work shows relevance to engine oil pumpability failure. Oils exhibiting pour reversion have solids resulting from wax gel formation, at temperatures significantly higher than their ASTM D 97 pour points.
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Translation: A highly redacted beginning of a description of a test regimen with too much deleted for the remainder to be useful.
Geez, try to find something online that isn't this^. It ain't there!
