- Jun 13, 2016
Very true. Although, I'm basically convinced that an oversize Fram Ultra for my application (small engine, 1.5L, uses Corvette's PF64) will avoid bypass events well enough. Based on some data estimates and basic hydraulic pressure-area trends using more media surface area than standard. ... Yes, we could use better data though!
Originally Posted by ZeeOSix
We'll never know that without seeing some flow measurement data.
Yes. Wix, and the same clone NAPAGold, do seem to follow GM, Subaru recommendations, two manufacturers who believe in high bypass thresholds. Good efficiency there too, about 95% at 20 microns using a glass-paper blend media, better than paper filters.
Originally Posted by Ablebody
So am I right in understanding from some repies to this thread that wix is good about making filters to the manufacturers specs?
Very true. User 'webfors' on these forums, on his '17 ATS (GM 2.0L turbo) had a flimsy paper PF64 get a rip in it, not good. Makes you wonder if the PF64 is really built that well. Engines may not blow up due to a rip-tear in the media like this, and the GM warranty dept. knows this, but nobody likes a hole in their oil fiter media, right? Extra wear maybe.
Originally Posted by Garak
They sure talk about their own product and their own specifications as the only way to be, then get upset about patent infringement, as if everyone is in a rush to line up to copy the ecore design or brittle media in the first place.
Remember viscosity (cold!) raises the pressure a lot. So your 5 psi example only applies when cool-to-warm. Thats the key to understanding all this, that its +10F cold morning starts that will likely cause bypass events, and GM tries to minimize this to some extent. These GM oil pumps create a 'big-ish' pressure spike at startup time due to placement of the feedback control pressure sensor so far downstream (engines since 2012), which means the flow (GPM) can be high at first. GM discusses washing garbage past the media during these possible bypass events, and, like us, they don't want that to happen too often, hence where their concern is.
Originally Posted by carviewsonic
Even at that volume the Fram Ultra only drops about 5 psi, well below the bypass limits. I just don't understand what problem GM's service bulletin is trying to solve.
The line graph above shows the worst (Fram ToughGuard, old version of course, which I'll assume is like a paper PF64/63E) bypassing at +34F if a GM engine startup spike at 2 gpm (not sustained for a long time; just an initial open-loop spike) happens. Note that's +34F. Now lower the temperature to a typical winter morning +10F and, yes, you'll bypass often, especially with a restrictive paper filter like a PF64/63E that GM says is the cat's meow.
Originally Posted by ZeeOSix
I think GM is assuming people are going to do cold starts in -20F climates and rev the engine to redline before the oil warms up. I mean that's really the only way you could cause 20+ PSI across the media. Or else their AC Delco filters are very flow restrictive and produce lots of delta-p. We'll never know that without seeing some flow measurement data.