Originally Posted By: SonofJoe
In itself, the Noack volatility is a meaningless number. The test measures how much oil, when held at 250°C, evaporates into a stream of cold air over the course of one hour.
The reality is that your oil (typically at 100°C) might be exposed to a stream of hot blow-by for 300 hours. How much oil exits the crankcase with blow-by in this situation?
The answer depends on a whole host of variables? Do you drive modestly (like me) or in a spirited fashion (everyone else on BITOG)? Do you live in a non-extreme climate (like me) or do you live in a country that sees extremes of hot and cold? Do your engine see significant fuel dilution (from low tension rings, or because it's TGDI, or because you live in a cold climate?). Is your engine nice a tight (because it's relatively new) or worn out and letting through a lot of blow-by? Do you have a typical OCI of 3k miles or 15k?
I once ran an 11%-ish Noack oil of my own making and lost 40% of it over 15,000 miles!
I think you and I agree - there may be some engines where NOACK is a factor, but for most it's not. There's a lot of debate over whether an oil is 5%, 10% or 15%, but experience of most of us have is that regardless of which one is in the sump, your oil consumption is low enough that it isn't a concern. Or putting it the other way around, if you have a consumption problem, switching to a low-NOACK oil won't fix it.
I usually drive very conservatively, and if I drive conservatively in the 2015 Ford Explorer with the TiVCT V6, it burns no oil from one change to the next, and I'm running $2 a quart Chevron Supreme 5w20. On the other hand, if I drive conservatively in my 2016 GT350, it burns high-end synthetic oil at about a quart per 2000 miles. However, if I take the GT350 and roar around a racetrack all day, it has a big impact on oil consumption: it stops! I burn more oil getting groceries than I do flat-out at 130MPH. Go figure. Not only that, the amount of oil in the catch can doesn't seem to change much either, although my belief is that the catch-can contents is fine droplets entrained in the crankcase air, and not some vapour that distills off the oil in the sump.