K&N Oil & Fuel Filter

Never tried the fuel filter, just the oil filters.

I think they are over-priced myself. Consider them only if you run high-RPMs often ... like autocrossing. I think they use a less-dense media to ensure uninterrupted flow.

However, a Wix filter will do the same thing for about half the cost, same with Hastings/Baldwin. And those companies make top-notch filters.

I merely avoid the high efficiency filters like Pure-One and (especially) Mobil 1. At $10 a piece, I don't see why anyone would use them.

And I find that nut welded on the back of the K&N filter to be all but worthless.

Wix is my preferred filter, but I do have ONE hobby car that gets the Mobil 1 filter for reasons having nothing to do with filtration. It kicks up over 90 PSI of oil pressure on cold start, and gets driven so little that it only gets an oil change once a year (or even longer). The cost isn't an issue at that infrequent change interval, and the heavy guage filter canister seems like a good idea with that kind of oil pressure. The base-plate is also thicker and captures about 4 more threads than Wix or Purolator standard filters do, so the chance of the filter blowing off the pump seems like it should be lower. I'd feel even better if I had actually seen any info on filter bursting or separation from the baseplate, but I haven't so this is one case where going by the design of the filter can seems to be the best option.

Other than that, I see no use for the Mobil 1 filter either.

Hey now, it takes a lot of snakes to produce one single drop of the special high priced oil they sell...

I've always been leary of that. Are you SURE that's a GOOD thing? Pressure is a resistance to flow. How do you know that the extra restrictive filter isn't cutting off oil flow to critical parts?

If the filter is restrictive and that's what's causing the increase in pressure, wouldn't the oil flow downstream of the filter be compromised?

--- Bror Jace

Well, yes and no. Pressure is equal to the product of flow times resistance. In other words, high flow through a fixed resistance (bearing clearances, lifter clearances, etc) will cause a higher indicated pressure than low flow through the same fixed clearances. But you're also right in that the same (or even less) flow through a higher restriction will also show higher pressure, depending on WHERE the guage tap is located (see below)...

Because the engine's pressure tap is the *last* thing in the plumbing (big block Chrysler). Its downstream of the filter, downstream of all the feed passages to all the main bearings, and at the downstream end of the lifter gallery. It shows the lowest pressure inside the oiling system in the whole engine. A pressure drop across the filter would show up as a lower pressure on the car's pressure guage in this case (which is why I hate cars that have their pressure tap upstream of the filter- the guage is telling you NOTHING about what the bearings are actually seeing). With a downstream guage, high pressure is necessarily caused by high flow through the filter, and in this case is caused by the fact that I'm using a high-volume oil pump. The only down-side to this (so long as I use a filter that doesn't go into bypass too easily) is stress on the filter housing when cold and a little more parasitic power drain off the engine to drive the larger oil pump. But I prefer running engines with a ton of low-end torque at higher oil pressures because of the higher loading on the bearings under those conditions as opposed to high-RPM lower torque operation.

You're correct, pressure drop ACROSS the filter isn't a good thing. But its not an altogether bad thing either. I personally distrust filters that cause unusually low guage readings on my cars (too restrictive filter media, possible indicator of filter media collapse, etc.) or those that cause unusually high readings (probably the filter media isn't dense enough, or, God forbid, the bypass spring is weak and the oil isn't even getting filtered!) If I put on a new filter and the oil pressure behavior changes too much from what I normally see with clean oil of the same weight and a new filter, I pull it off and throw it away and put on another one.

(snip)

Well Steve, you've obviously put a lot of thought into this and know the particulars of you car's plumbing.

I run into kids all the time who swap filters and feel most pleased with the one which shows the highest oil pressure. Without knowing your engine's plumbing, this is just foolish.

--- Bror Jace