Originally Posted by voxmagna
When you start up a K12 on mornings below freezing and the engine oil is heavy, Does the motor have its own pressure relief valve to bypass the filter, or does it rely on what may be inside the filter and are we sure that all non-oems have it? If the bypass is in the motor before the filter back to the sump, this doesn't help because whilst oil pressure is maintained, it's going nowhere except returning to the sump until the motor warms up.
I can't see how orientation helps this situation.
You're mixing two different vavles. Orientation is important on a filter that is not mounted vertically like the BMW filter. BMW OEM filters do NOT have an antidrainback valve.
As for a bypass valve, what do you think would happen if you didn't have a bypass valve in the morning? You seem to be implying that the engine might be damaged. You are correct, it might, but not the way you are thinking. The oil pump is a positive displacement pump which means it will be pumping even if the discharge pressure goes up. I don't know if the K12 has an oil pressure regulator but even if it does, it is set at a very high pressure. The paper in your filter isn't going to hold back the pressure but it will probably hold back enough pressure to blow the rubber gasket (I've seen this happen on a pickup truck when the bypass filter failed closed). Then all the oil drains out and the engine will be damaged...ooops, the K12 has the filter in a chamber so even if your oil filter blows out, the engine won't be damaged.
I've never seen an oil filter without an integral bypass valve for when it it clogged or oil viscosity is high (this can be minimized by using the proper multiviscosity oil for your climate). If you know of one, please let me know.
Perhaps you're one of the guys who believes in always using OEM BMW parts. If you are, I don't want to change your mind. But I like looking at aftermarket parts, many of which are superior (eg, ohlins shocks) or cheaper (bosch oil filter). What I don't like is people who make skeptical posts, implying great damage to the bike if you don't worship the BMW gods at part purchasing time. I don't think that's what you were trying to do but I'll admit that perhaps I tend to over react.