Originally Posted By: sayjac
As for not having earlier 'problems' that may be true too. But skyactive on the first page here makes a cogent point imo, regarding using a much than lower bypass spec. I'd say if the oem is using a significantly higher bypass spec as it seems on 'some' Subys, they must be doing so for a reason.
+ 1 ... Nobody could really tell if the bypass valve is opening or not while driving around. And if the bypass valve was opening a lot, it's not going to cause any real damage anyway since the oil flow volume is basically going to remain the same due to the positive displacement oil pump. It could however cause undue engine wear if debris flows through the bypass valve, but again nobody is going to know that unless they tear down an engine and look/measure for wear. The engine isn't going to blow-up instantly.
I've posted this many times showing what the flow vs delta-p data/curve looks like for a PureOne, which will be similar for other decent flowing filters on the market.
PureOne Flow vs Delta-P Thread
These crazy Subaru engines that flow 12~14 GPM near redline would still only create about 5~6 PSI delta-p across a filter like this. If the bypass valve was set to 12~16 PSI then there is still some headroom before the bypass valve would open.
But IMO, Subaru is probably increasing the bypass valve setting for other reasons to go along with the high volume oil pumps used in their engines. Like maybe their filter is more restrictive, they want more headroom for cold oil flow situations during higher engine RPM and also for media debris loading factors.
One thing is for sure, if an oil filter can take 23~25 PSI of delta-p across the media and center tube, then that media and filter is built pretty tough - and that's with some safety factor on the design. Sub quality filters might self destruct with that much delta-p across it.
As for not having earlier 'problems' that may be true too. But skyactive on the first page here makes a cogent point imo, regarding using a much than lower bypass spec. I'd say if the oem is using a significantly higher bypass spec as it seems on 'some' Subys, they must be doing so for a reason.
+ 1 ... Nobody could really tell if the bypass valve is opening or not while driving around. And if the bypass valve was opening a lot, it's not going to cause any real damage anyway since the oil flow volume is basically going to remain the same due to the positive displacement oil pump. It could however cause undue engine wear if debris flows through the bypass valve, but again nobody is going to know that unless they tear down an engine and look/measure for wear. The engine isn't going to blow-up instantly.
I've posted this many times showing what the flow vs delta-p data/curve looks like for a PureOne, which will be similar for other decent flowing filters on the market.
PureOne Flow vs Delta-P Thread
These crazy Subaru engines that flow 12~14 GPM near redline would still only create about 5~6 PSI delta-p across a filter like this. If the bypass valve was set to 12~16 PSI then there is still some headroom before the bypass valve would open.
But IMO, Subaru is probably increasing the bypass valve setting for other reasons to go along with the high volume oil pumps used in their engines. Like maybe their filter is more restrictive, they want more headroom for cold oil flow situations during higher engine RPM and also for media debris loading factors.
One thing is for sure, if an oil filter can take 23~25 PSI of delta-p across the media and center tube, then that media and filter is built pretty tough - and that's with some safety factor on the design. Sub quality filters might self destruct with that much delta-p across it.
