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Tho' i posted this on this Forum under the oil filter canister thread begun by new member '46 Deluxe Clipper, it occurs that this might be of interest to those not clicking on that specific topic. Most Packards, if they have an oil filter, have a bypass, so i thought the below interesting:

Expanding a bit on the above discussion of bypass vs. full flow filtration, here's an interesting letter in the
2006, No.5 Auburn-Cord-Duesenberg Newsletter by Al Light,
Williamsport, PA, which is, coincidentally, where Lycoming was, perhaps still is, based:

"I really enjoyed the editor's comments on the club website about the real value of having an oil filter.

In the early 1950s while at Ford Engineering I was fortunate to hear an argument of "Full Flow" vs. "Partial Flow" oil filtration. The pro "Full Flow" people seemed to be more interested in the positive sales pitch that this system provided while the "Partial Flow" people seemed to
have a more solid engineering approach. The chief engineer from Fram Corporation stated the big difference was the allowable filter pressure drop. The larger the pressure drop, the finer and more material will be caught. With the full flow system you are restricted to approximately 10 pounds per inch drop across the element, and also require a bypass valve that will open when this pressure drop is exceeded. This of course is to protect the engine from oil starvation in the event of a plugged filter. With the partial flow, or sometimes called bypass system, the pressure drop is full engine oil pressure since
the oil discharges from the filter directly into the oil pan and not under any pressure. The system is automatically
bypassed if the filter plugs. It was also noted that a denser filter element is used on the partial flow system.
The Fram engineer summed up his thought by stating the answer to the argument was obtained by considering the following question: "Is it better to filter all of the dirt from part of the oil or to filter part of the dirt from all of the oil?"

He also stated that with the full flow system the bypass valve may open under cold starts and sometimes opens at high engine RPM when the allowable pressure drop may be exceeded. This results in no filtration under these conditions. His other comment was that the biggest advantage to full flow was to catch the machining chips, etc. in new engines. Fram's final approach was to propose the use of a combination system that did both full and partial filtering. I'm sure that this would have increased their filter business. I am not aware of any such system ever being used."


I can only add that an auld aircraft/auto mechanic/machinist/pilot and blown '37 Cord 812-owning friend said they were taught in tech school that a bypass filter will eventually filter all your engine's oil after a drive of 60-70 or so miles.

Another friend with '59 and '63 Lusso Ferraris showed me that one of these cars, and i forget which, came with both full and bypass filters from the Modena factory, as do some more recent trucks and heavy equipment,some of the latter coming only with bypass filtration. Such equipment is likely to run hour after hour, shift after shift, so all the oil would easily be filtered.

As we've observed, for all the technological breakthroughs since Packard folded, much engineering is cost engineering,
but i don't know if this is strictly the case regarding bypass vs. full flow oil filtration with internal combustion engines.

Perhaps the above will be of some solace to those of us with Packards with the usual bypass filters. I leave further discussion to others, but would especially like to hear from engineers like Al Light, above, and members of the SAE.

IMHO, '46 DeluxeClipper, if you clean out your oil filter canister as the gent above describes, perhaps drop your engine oil pan to get rid of the inch-deep sludge and lead coating its bottom, assuming your engine has never had serious work since leaving East Grand,

then use a major brand 10W/30 oil and change it and the filter periodically, you'll be in fine fettle. If your original engine's worn but still serviceable, and you don't want or need to rebuild it, you might use a heavier weight oil.

Finally, never, ever start the engine unless you're going to drive the car at least 17-20 miles on the highway to prevent the formation of sludge, varnish, carbonic acid, the latter strong enough to etch concrete so you can imagine what it does to your bearings and rings. If you want to wash, wax, or work on your car outside, push it out the garage.

We still shake our heads at the alleged car buffs who start their engine and run it for a few minutes to show it off in the garage, then switch off the ignition and let the car sit for a month or two or longer.

You succinctly summarize the pro/con arguments of full vs partial flow filters. I've seen essentially the same discussion on the high performance Pontiac forums.

I am personally an advocate of the full flow system and for those not familiar with same, I have developed and installed same on a couple of Packard V-8s.

One has to ask oneself: If the partial flow systems are so good, why has every manufacturer (who now warranties their engines for 100K+ miles) gone to the full flow design?

The question answers itself.

Craig

Thank you for the kind words, but it was automotive engineer and Auburn-Cord-Duesenberg member Al Light, above, who "succinctly summarizes" the pro/con full flow vs. bypass oil filters.

I post them here, followed by a few comments, quotes from
other technical folk, as i find them interesting, though my Ferrari-owning friend is a senior staff electrical engineer for a major utility company, not a mechanical or chemical engineer.

Sounds like the jury's still out, given that for all the
advancements since Packard folded, much engineering is cost engineering. Would love to hear more insight,
especially from any Packard/vintage/Classic car buffs who happen to be engineers and/or SAE members, with
access to hard, vetted studies.

I tend to agree with you, that full flow, on balance,
might be better across the board. But i'm just a curious Packard owner/enthusiast. For the occasional extremely "light duty" exercise runs many of us limit our Packards to, the above discussion, question is strictly
curiousity.

Meanwhile, the above does suggest that, especially given
the night and day better motor oils today than when our Packards were new, we are in fine fettle with bypass filters.

Given the request for comments, I'll throw my two cents in.

Today's highest cost prime movers use full flow plus bypass. The bypass is a multi-stage filter. They also use pre-cleaners in addition to primary and second stage air filtration.

If you can find a good engineering library you can check out editions of the "Handbook of Petroleum Engineering". They contain filtration studies some of which concluded that diesel locomotives were ruined after three months without filtration.

For these Packards there are a couple of very important considerations.

One is that when these cars sit parked for more than a week the settlement effect is virtually the same as full flow filtration. When they sit for a month the results are way down in the microns.

Secondly, the floating pick up is very effective. Modern cars don't have floating pick ups any more because of full flow filters.

After that the air filter is actually more important than the oil filter. And that is according to the Packard company. I remember an old timer who fitted an oversized paper filter to his original 902 and it ran for years and years without a rebuild. For any car without the optional oil bath cleaner I would follow his lead.

Finally, emission controls and unleaded gas have cleaned up the crankcase which is why modern engines run so long without blowing up. In fact, motor builders have to engineer failure into modern engines so that they have to be replaced. A million miles on an engine is entirely possible given changes in the computer program cells and sturdier parts.

Thank you, Dr. Cole. All excellent points, and the experience of the auld gent with the 384-ci Model 902 with
the outsized paper air filter is new to me. I've been running a Wicks 87055 in my '47 Super's oil bath cleaner since the late '90s which fits like a glove.

When i changed my oil and filter last New Year's Eve afternoon after only 985 miles since the previous change simply because of the time, not mileage, that had passed, it looked about as clean as it did at 100 miles. As mentioned, i never, ever start the engine unless i'll be driving 18-20 miles highway to equalize block, head, manifold temperatures and prevent sludge, varnish, carbonic acid as mentioned above.

A Cordite friend installed a full flow oil filter on one of his Cords, something a few 1936-37 Cord owners have done probably since the three-main-bearing Lycoming V-8, same bore/stroke as Packard's 1948-54 inline 288, shares oil with the transmission, Cords being, as we've read and heard, underfunded, underengineered.

We already know how cheesy even the upper echelon GMobiles were compared with concurrent Packards, but it's
interesting that the 1936-48 Cadillac three-main-bearing 346-ci (320-ci in '36) L-head V-8 using the same Wilcox-Rich hydraulic valve lifters as the 1940-50 Packard nine-main 356 L-head inline 8 offered an oil filter as an option, while it was standard equipment on the Packard 356.

Already have a pre-oiler on my car for full oil pressure
before turning the starter, since according to McDonnell-Douglas, Continental, the SAE 80-90% of all engine wear occurs during the first moments of start up after an engine's been sitting more than a few days, or a week, let alone a month or more.

So, short of drilling and tapping our blocks for full flow, i'm sure many of us would like to preserve our Packards "for the duration," and are all ears when it comes
to such insight as yours above. Thanks again, sir.

Quote:
"Already have a pre-oiler on my car for full oil pressure
before turning the starter, since according to McDonnell-Douglas, Continental, the SAE 80-90% of all engine wear occurs during the first moments of start up after an engine's been sitting more than a few days, or a week, let alone a month or more."

I doubt that to be the FULL description of ALL the facts.

Greatest engine wear is due to placing demand on the engine BEFORE it reaches some 60%-70% of operating temperature. Especialy HEAVY demand. ESPECIALY in cold weather. Constant and significant heating and cooling cycles between start up's (even if it's multiple times per day every day) is just as bad for wear if operating temperature is not attained before placing demand on the engine any more than just idling to warm up.

Does Mcdonnel DOuglas and Cont run preoilers on their engines that do NOT HEAT the oil ??? Probably oil or block heaters only for the purpose of keeping the engine warm and not for sole purpose of oil circulation.

Quote:
"Finally, emission controls and unleaded gas have cleaned up the crankcase which is why modern engines run so long without blowing up. In fact, motor builders have to engineer failure into modern engines so that they have to be replaced. A million miles on an engine is entirely possible given changes in the computer program cells and sturdier parts."

Yes. But there is another major factor involved that has nothing to do with any technology. Attempting to compare J.Q.Public passenger car operation of the last 20 years to any such operation of the 1930-1970 era is grossly lacking in objectivity.

Not uncommon to find modern cars less than 3 years old with 30K miles or more. Some 15 to 20K miles of driving per year. Such high mileage driving habits rarely occured 40 years ago unless it was some traveling salesman or fleet delivery operation which would not be in the realm of J.Q.Public operating habits.

Therefore, the engine stopping and starting and heating and cooling cycles of modern driving habits is much less frequent than of some 40 years ago.

I'll certainly agree that modern tech has significant impact on better longevity of modern engines but modern tech is more sensationalized than the reality of various other factors not related to tech.

ANd at what cost is the modern tech???? $700 'brain boxes', $20-$40 spark plugs, EFI, $300 in tank fuel pumps .... THat list goes on and on. Mite be cheaper to replace an engine every 120K miles. Maybe not.

THink about that the next time anyone is out there on the side of the road, broken down, trying to live life from a cell phone, plastic card and an auto club extended waranty program. How many of those SPARE $700 computer boxes do they caryy in the trunk???? I keep a $10 set of points in the glove box. J.Q.Public probably scrap the car after 15 years anyway. No???? I sit rite here and watch them go to the crusher everyday. Some of the cars look better than the tow car pulling them in. But that's a whole different real world issue in itself. We'll see in 3 or 4 years who really cries the tears.