Larger oil filter for better FE?

[Shawn D.]

Originally Posted by mcmancuso

Sorry, not my intent. I don't care about level, I was thinking of total oil in the system. the metro only holds 3.5qt, and I feel a lot better knowing that if I'm a qt low there is still 3 in the system instead of only 2.5. A qt low is a much smaller percentage of 4 than 3.5. Its not margin, and I know that the extra 1/2 qt is in the filter not in the pan.

In that context, the only way having an extra 1/2 quart would be beneficial would be damping spikes or drops in oil temperature. Is that your intent?

[mcmancuso]

no, more what comptiger said,at 1qt low I'm down by 25% capacity instead of almost 30% better dilution of contaminants and more additives present, especially since I go about 10K between changes. Oil pressure/temp? I don't know why I'd be concerned about that at all in daily driving situations.

[comptiger5000]

On any engine I've seen or heard of, the oil pump is connected directly to the pickup tube that draws from the pan. The oil is pumped through the filter under pressure, although the sender for the gauge is after the filter, so a restricted filter will show as lower oil pressure. The can on the filter is surprisingly strong, and most can handle over 100 psi of oil pressure without bursting.

There have been rare occurrences, however, of filters exploding when a cold engine with thick oil is redlined, and so much pressure builds that the oil pump relief and filter bypass cannot flow enough to relieve the pressure, and the filter either blows off, or explodes.

[Shawn D.]

Originally Posted by ShadeTreeMech

there seems to be a misunderstanding about something concerning oil filters.

After the oil is sucked from the sump, it's next stop is the oil filter. Then the oil goes to the pump; IE the filter is within the suction part of the system. If you've ever had to stab a filter with a screwdriver to remove it you'll know the metal is rather thin. Would hate to subject it to 80 psi.

The oil filter rep talking about the 20 psi differential hinted at it if you look carefully at what he was saying.

That is incorrect. As comptiger5000 says, every engine I know of has the arrangement of pickup -> pump -> filter. I would be very surprised if you came up with any example of the arrangement you're suggesting.

As for the filter metal being thin, a can shape is far more likely to crush under vacuum than it is to burst under pressure. Under vacuum, the material is under compression and tends to buckle, whereas under pressure, the material is in tension and resists deformation.

Dunno what you're hinting about when you're talking about someone else hinting about something!

[JohnMcD348]

I'm still fairly new to all this but I would think the size of the filter really wouldn't do anything for you except allow a slightly larger amount of oil to be in your engine lubrication system at any given time.

Say, for example you use a Fram oil filter, no matter what size it is, they all use the same basic filter media. The only difference that the size makes is the volume of oil it holds.

[Phantom]

Originally Posted by JohnMcD348

The only difference that the size makes is the volume of oil it holds.

Also the amount of crud the filter can capture before being full think of it as your motors trash can.

[Funny]

Originally Posted by JohnMcD348

I'm still fairly new to all this but I would think the size of the filter really wouldn't do anything for you except allow a slightly larger amount of oil to be in your engine lubrication system at any given time.

It's okay that you aren't sure of the benefits, you came to the right place for info! I work for the company that sells filter media to Honeywell(Fram). If you increase the size of the filter, the area of the filter media increases. The oil pump can only output a specific amount at a given rpm, that doesn't change. What does change is the differential pressure against the filter. At a given pressure and area of media, There will be a certain face velocity, or speed at which the oil hits the filter. If you increase the area of the media, while all the rest of the system stays the same, the face velocity decreases.
This has several benefits. First, a lower face velocity means better filtration, the particulate matter hitting the filter is moving slower, and has a greater likelihood of being captured. Secondly, a larger surface area decreases the back pressure on the oil pump with cold oil, due to cold oil having a high viscosity compared to warm oil. Lastly, though not the last benefit, the larger surface area means a greater capacity, so the life of the filter increases.

Originally Posted by JohnMcD348

Say, for example you use a Fram oil filter, no matter what size it is, they all use the same basic filter media. The only difference that the size makes is the volume of oil it holds.

It depends on the line of filter, but I think I know what you're saying. The Fram Tough guard is tighter filter media than the standard media. The Fram Xtended guard is far superior in construction (metal end caps, expanded metal backing, dual-layer synthetic media, I know, I helped design it , though Honeywell has dropped the ball in the marketing department and doesn't advertise for squat - but that is another thread.) and has MUCH high capacity than the other media in the Fram lineup. So, if you pick up a regular Fram filter and then get a larger sized tough guard filter, the back pressure is probably going to be similar, due to the tightness of the Tough guard, but you will have a larger area and smaller pores (better filtration). I hope that clarifies the subject. Just ask if you have any more questions. I love this stuff, because it's what I do everyday!

[aerohead]

I took baby-food container samples of a half-dozen motor oils,from Honda's 0 wt-20,to 5wt-30,10wt-30,10-40,etc.,and placed them overnight in my freezer ,at 0-degrees F.
Next morning I pulled them all and did a 'tip'-test,turning all of them over simultaneously.
All of them essentially poured out within the jars at an equal rate.
From that observation I would deduce that the cold pumpability at the filter media is not a real issue for us.
Your pressure bypass may exist to 'maintain' oil pressure within the lubrication system,modulating between cold and hot conditions,and as the engine rpm( and pump rpm) varies from idle,up to redline.

[Christ]

Phil -

It's too bad you had no way to measure film thickness at freezer temperatures... that would have been an interesting comparison between the various oils.

[Shawn D.]

Originally Posted by aerohead

I took baby-food container samples of a half-dozen motor oils,from Honda's 0 wt-20,to 5wt-30,10wt-30,10-40,etc.,and placed them overnight in my freezer ,at 0-degrees F.
Next morning I pulled them all and did a 'tip'-test,turning all of them over simultaneously.
All of them essentially poured out within the jars at an equal rate.

Sorry, but dumping them out against zero resistance using uncontrolled pressure is a rather unscientific test. There are reasons why oil viscosities are measured using designated test procedures (ASTM D5293 and ASTM D4684).

Also, it's "W," not "WT" as oil isn't measured by "weight," but viscosity. The "W" denotes the cold-weather ("winter") viscosity. Otherwise, there would be a W after both numbers (i.e. 5W-30W) or the W would be at the end to denote a viscosity range.