Engine mfg's and oil Mfg's work together on oil specs. 5W-30 is specified for reasons related to fuel economy, valve train lubrication design (e.g see small oil channels), start-up lubrication performance, over all engine cooling.
Personally, having previously worked for Pennzoil and taken their lubrication training in Dallas, I would never go to a 15W-anything unless I had a deisel or the mfg spec'd it. 5W-50 Synthetic would Ok for extreme high temp operating environments. 0W-any thing would only make sense for seasonal application in extreme cold environments (like the arctic).
Hope this helps.
Last edited by PeterM; 04/15/03 01:08 AM.
