I'm contemplating installing a Fram Ultra Synthetic (XG) filter. Fram specifies a shorter filter for my application (different model number in the PH series), but this XG filter has the same threads and a similar bypass setting.
1. Are Fram XG filters restrictive to flow? Some have suggested the high efficiency rating leads to flow restriction, while others say the synthetic media makes it easy-flowing.
2. Is it a problem that the bypass rating of the Fram XG is slightly higher than that of the OEM filter I plan to replace? Is this problem mitigated or exacerbated by the Fram XG's flow properties.
3. As the Fram XG filter is designed for a long OCI, are there any drawbacks (besides the price) to using it for short OCIs? Someone suggested that it may sacrifice fine filtration at the expense of high capacity, but I've seen other reports to the contrary.
1) all filters restrict flow to some degree. But so do the walls of the flow path (engine oil galley, piping, etc). Nearly anything that flows a fluid (gas or liquid) will present some form of restriction; NOTHING is frictionless. Friction in a fluid directly affects pressure loseses, and to a lessor degree, flow losses. But that's a TECHNICAL answer and probably not helpful in your underlying quest.
The thing is this ... you're asking a quesiton in the wrong manner. You probably want to know if the XG filter is "too restrictive". Well, then you have to define what "too restrictive" means.
A much easier way to look at this is by asking two questions in a more defined manner:
- how much oil will the XG filter flow before it goes into BP?
- how much oil will my engine require to flow at max flow capacity
Though these answers will be slightly different for each unique filter model, and engine engine model, the reality is that ANY decent filter will flow much more than your engine requires.
Example ... if you engine produces 6 gpm at 5000 rpm before it goes into BP at the pump relief at 85 psi, then the oil filter will see approximately 6 gpm to the filter media (minus the aforementioned frictional losses). But most decent filters will flow 9-11 gpm. So, the point you seek to worry about is moot. Forget it and move on. Even if the oil is really cold, the filter BP would open and still flow for that very short time of BP event. As Zee said, don't mash the go-pedal when the oil is cold and it'll be just fine.
2) Prob's not. If the BP value of your engine design requirement is only a couple PSI different than the filter, it's not a big deal.
- hopefully, it would be a rare event that the BP would engage in the first place (again, see Zee's comments)
- I've seen many examples where one filter maker has a BP value slightly different than another filter maker, all for the same application. If it were so darn important that they matched exactly, the filter makers would be more worried. Since they are not worried about matching EXACT dP for the BP values, you should not worry either. As long as you're within a few PSI one way or another, it's moot.
3) Well, if you're going to ignore price, then I'd have to say "no", there are no drawbacks to using and XG for short OCIs. The XGs have admirable efficiency, high capacity, and solid construction. The only drawback is under-utilizing the filter, but your premise is that it's OK to waste money, so that's out the window as a concern.
I am curious about the specific application; I've never known Fram to spec an EG different than XG for the same application. Assuming that you are correct, that Fram specs two different filters for the same applicaiton, then as long as you choose either, you'd still be fine. Please let us know what the actual application is; I'm curious to know.
