In more than 30 years of doing oil changes somehow the significance of the phrase "energy conserving oil" has escaped me. I suppose if I ever saw the phrase I assumed it was a marketing slogan. However my 1996 Golf owners manual states that for 10W-30 engine oil, the energy conserving type can be used for ambient temperatures up to 100F whereas the multi-grade type shouldn't be used above 59F. Is there really such a difference in the performance of these oils? I have several cases of Castrol GTX in my garage and I noticed that some of it is labeled energy conserving and some is not. It's surprising to me that the same product name and viscosity rating would be used for two oils that apparently have very different applications. A few weeks ago my oil pressure light and audible alarm came on briefly a couple of times. I never saw this before. It's been hot this summer. Assuming I have multi-grade in the engine (I don't know which of the two in my garage I used), could this be the cause of the oil pressure warning?
Ray