quote:My theoretical tribology isn't quite good yet, but a hypothetical based upon this. If 5w-30 has no VIIs, what does 10w-30 use as a basestock? It has a lower VI but the same HT/HS Vis. Is it simply just a 'thicker' (when cold) POE molecule? ferb! edit: for clarification [ January 23, 2004, 02:10 PM: Message edited by: Ferb ]
Originally posted by Jeffrey Behr: ...use the 5W-30. It has NO Viscosity-Index Improvers (VIIs), which are a slight performance compromise, whereas the 5W-40 has some (to get to '40' when hot).