Quote:
Originally Posted by Isaac Zackary
Another "concern" some people have with multi-grade oils is that multigrade oils contain viscosity modifiers which kind of take up space in the oil meaning that now you have another ingredient that supposedly might deture other ingredients from doing their job. A 0W-30 is going to have more viscosity modifiers than a 10W-30. Straight 30 has none. Personally, I really don't think that viscosity modifiers affect the oil's job of lubricating like that.  |
This is where synthetic oils come in. I get a kick out of reading posts by people claiming synthetics are "slipperier", or who are sure their engine "runs smoother" on synthetic oil. The benefit is a naturally-wider viscosity range, requiring fewer viscosity index improvers that
could break down over time.
Back when I frequented the Viper forums, there was an oil formulator for Texaco and Shell who posted in threads about oil choice (which, as you can imagine, came up frequently there). He ran a 5W-40 or 15W-40 diesel oil, non-synthetic, whatever-was-cheapest-at-Walmart through his Viper (factory fill on the Viper was Mobil1 10W-30 to 2004, then Mobil1 0W-40--a change made not for viscosity, but because of the higher ZDDP in the European oil when API standards changed). I started using Shell Rotella 15W-40 in mine, both the car and truck. Now, I use whatever the manufacturer put in (synthetic blend 5W-20 in my last car, regular 0W-20 now). I think people concern themselves way too much with oil selection when, for most of us, it doesn't matter that much.