[asavage]

The difference between a really bad oil filter and a really good one is not, IMO, worth worrying about all that much (see caveat below). If you are really serious about clean oil, bypass micronic (or some say submicronic) filtration is the only route. However, there are several ways to do lube oil filtration to the one micron level.

The best full-flow oil filter isn't going to get within an order of magnitude near one micron. Most won't filter (when the filter is brand new) even the 30 micron, aggregate. After it's been installed a while and begins to plug up a bit, oil filters do filter a bit better (ie to finer particulates), but compared to bypass filtration, it's not even remotely close.

Google search terms: Gulf Coast, Motor Guard, Trasko, Frantz, Filtration Solutions World Wide, Puradyn, Glacier Centrifugal

When you buy a "good" oil filter, what you get is better anti-drainback valve material & construction (stay far away from Fram!), better can thickness, better can-to-base seal, and maybe a sturdier core to help prevent collapsing. There is some performance difference in the media, but it's not all that much.

I buy OEM or Wix, and only Wix's top line (what is sold by NAPA as "Gold" filters), that have silicone anti-drainback valve material and heavier can material.

The site bobistheoilguy.com is one decent resource to learn about this stuff, but there's as much misinformation as information on the internet about lube oil filtration. Everybody's got an angle.

Disclaimer: I own two Motor Guard Model M30s, modified by Ralph Wood, so I'm invested. I've also got two or three brand-new preluber units kicking around. And most of my next water injection setup parts, brand-new in boxes. And a 300ZX turbo. Someday . . .

[philip]

Well then ... it's reassuring to know NAPA oil is a Valvoline product and the NAPA Gold oil filters are a WIX product! I have been using the NAPA GOLD 1068.

[philip]

SNIP ....but compared to bypass filtration, it's not even remotely close.

I just had a curious thought about bypass filtration.

On the SDxx, there is a handy access to the oil gallery port feeding the vacuum pump. Al, do you see any reasons for not plumbing a bypass filter in series on the line feeding the vacuum pump?

[asavage]

The NAPA Silver (Pro-Select & NASCAR) are also apparently Wix, but if you heft them one in each hand, you can tell by the weight alone that something's missing from the non-Gold oil filters. I think Wix makes these cheaper filters specially for NAPA, as I've never seen them sold under the Wix name.

In NAPA-speak, the non-Gold oil filters' part Nos. begin with a "2". Wix oil filters begin with a "5" and for NAPA's Gold oil filters, NAPA just drops the "5" off. Clear as mud?

[asavage]

On the SDxx, there is a handy access to the oil gallery port feeding the vacuum pump. Al, do you see any reasons for not plumbing a bypass filter in series on the line feeding the vacuum pump?

That is surely the easiest method, yes. It makes a retrofit of a bypass oil filter setup easier to do on an SD or LD than on a comparable gasser -- no piercing the oil pan, something many folks are reluctant to do.

Other oil return methods are through the oil fill cap (drill/tap the cap for a 90° fitting), and the valve cover (put the return line fitting in the cover somewhere). Some engines don't like the add'l oil volume up there, though I doubt this would be a problem on either the SD or LD -- but since we already have the plumbing in place on the sump, it's not an issue.

I plan on a regular plumbing Christmas tree on mine: oil return for the vac pump, turbo, and bypass oil filter. Because the turbo whips the oil into a froth, the stock sump fitting may be too small. I might drill/tap the valve cover for the bypass filter return line. I haven't decided yet.

Ideally, the turbo return line should be above the oil level in the sump.

[Zoltan]

I chose Mobil1, because it has a drain back valve that actually works and it filters down to 10 micron. My problem is that, in Hawaii, I can get only the Pennzoil or Fram filter, both of which is made of paper, filter to 25-30 micron and god knows if the drain back valve works or not. I called Champ labs about their Wix filters (one store started carrying them). They are made of reconstituted cellulose and they filter to cca 25 micron.

[asavage]

I chose Mobil1, because it has a drain back valve that actually works and it filters down to 10 micron.

You sure about that? I am sceptical, esp. its new performance (ie before it has been in use for a while).

Cellulose is a very good filter media, but only when packed.

[philip]

Ive run both of those filters in my maxi, with the same brand and weight of oil, with the same ambient temperatures and I just pull better overall pressure with the NAPA filter

For you to notice a difference in running pressure means the oil pressure sender unit is positioned after the oil filter. For there to be lower pressure with a different filter suggests the other filter is more restrictive which can be due to denser (finer filtering media) than your chosen NAPA filter.

OR ... if the medias are the same density, then the chosen NAPA filter may well have an internal bypass valve having a lower opening pressure threshold than the other filter. Remember, the bypass valve INSIDE the filter regulates the pressure difference between the inlet and outlet sides of the filter media. Worst case senario: Dense filter media and cold/thick oil will create the most pressure differential which in turn makes the internal bypass valve pass more oil, unfiltered.

It is worth noting that the SD flows a lot of oil for a four cylinder engine. In addition to the normal crankshaft and cam delivery points, the SDxx oil system also feeds FOUR piston cooling sprayers, a vacuum pump, the fuel injection pump, and a cam gear sprayer. These additional pressue loss points illustrate the need for an oil filter capable of flowing a lot of FILTERED oil.

SD22 oil system

[kassim503]

By visual inspection, the Pure 1 seems to have a thicker media than the NAPA, and the pure 1's media is also more restrictive too.

Probably wont go back to the Pure 1's, sales of them seemed to "dry up" in this area and the only place i can get one is 40 or so miles away.