And yes I'll have to look into how much zinc is in the oil I already use.

I was able to get a number of oil filters today and do a comparison.
WIX 51086, WIX 51515, WIX 51806, Purolator L14670, Purolator L30001.
Purolator offers different grades of filters as well, such as regular Purolator, PureOne, and Boss, so I compared those also.
The Purolator filters don't have an extra piece of metal and a rubber gasket that the WIX filters have, but they specifically advertise on the box that the have anti-drainback valves - so the differences don't matter much, I would think.

The WIX 51806 is the most interesting filter to me since I can see the metal standpipe inside the filter that would help prevent drainback if your oil mounting doesn't already have a stand pipe.

I have yet to test the different filters, but I will be doing that very soon.

I've come to the conclusion I won't use STP additive anymore.

I'll have to research how much Zinc the oil I use has in it. If it doesn't have enough, I'll use a different additive than STP.

Thanks for the help, everyone.

I usually buy oil filters by the case at NAPA, when they have their 2x a year filter sale. I get the 1068, tallest one that will fit my Dakotas/Durango. Last time I did a change I had somehow misplaced the case of them.... (if you saw my garage youd see why)
I went to Advance, as I had a $5 coupon to burn up. The salesman asked what oil I use. I told him regular conventional and he said that I "couldn't" use the "better" grade unless I used synthetic oil. BS... something about how the "better" filter won't pass conventional oil, can only use with syn.... BS!!!!

I also have most of a case of newer Fram "ultra" filters, in the 8A size that I got for free and use on my 78 Fury with more room between engine and frame. It too says something about being recommended with synthetic oils..... but not that it "can't" be used with regular oil....

I used to use Hastings from Federated until they switched to China prod. I used the last couple as hydro filters on my old Cub Cadet.
which brings up a question.... is it really worth spending extra on the "better" oil filters especially if you are good about keeping up with the oil and filter changes?
I remember the old Mopar factory service manuals and owners manuals said to change oil every time and filters every other time. I never agreed with that line of thought. I change oil/ I change filter too. Every time.

on another note, my Grampa had a 70 Hornet at one time, that he said he never changed oil, just changed the filter once a year because it burned so much oil.... back when I was too young to know how often you were supposed to change oil. He said he put 2 qts a month in that car, due to burning oil. but I have no idea how many miles that meant for him... at present for me, 2 weeks would be 750 +/- miles.

I could be wrong...but I am generally leery of old oil filters. I'm not convinced the media doesn't degrade over time, and I think some of them even use adhesives which I would also expect to degrade. In other words, I think filters can have a shelf life.

I also notice few people mention one of the most important aspects of any filter....efficiency and particulate size. Let's forget about efficiency for now and focus on particulate size.

I'd much rather have a $2.99 cheapie Fram filter than a well-constructed $10 Wix filter if the Fram is rated for 25 microns and the Wix is rated for 5 or 95 microns.

A lot of the fancy and expensive 'racing' filters are awesome - they don't pose any restriction to the oil. But the reason they do that is they are also not filtering out very much. The Oberg screen filters are an excellent example of this....for a racing application they might be good but not for any other application that goes more than 15 miles between oil changes.

The theory is you want to target and filter out any particles that are about .001"-.003". That's because anything smaller will generally pass through the bearing clearances, and anything larger will generally not be able to get in there in the first place. Another downside to filtering too small a particle is the additives used in oil can start getting stripped out of the oil. I've read that this is considered an issue at around 5-7 microns.

I've mentioned this before, but we used to have a 64 Valiant with a 225 that used so much oil we never changed it. We'd just add more, usually every couple days. We'd use used oil we drained from our 'real' cars, if we had it, to avoid buying new oil. And, the odd thing was you'd never see the car smoke or leak a bit...it just seemed to vaporize.

Uhboy, the zinc thing again…!

Short version:

Use a reputable off-the-shelf brand of engine oil. Avoid making the common error of thinking heavier-weight oil gives better protection—it does not. Using the lightest viscosity grade your engine's mechanical condition and your ambient temperatures will support will ensure quick lubrication of all parts at engine startup, thus reducing wear. For a Slant-6 engine in basically sound condition, 10W-30 is usually a fine choice. For a recently-built engine and/or use in cold weather, 5W-30. For a worn-out engine you're trying to squeeze a few last miles out of, 15W-40 or 20W-50 or straight 30- or 40-weight. Use good quality filters. Service the oil pressure relief valve to make sure it's doing its job, as described in these two threads: thread 1, thread 2. Avoid the temptation to put additives or "supplements" in your crankcase—at best they do nothing; at worst they do damage and harm, so just use unadulterated oil. Change the oil and filter at a reasonable and appropriate interval (3,000 miles is way too short; it's a pointless waste of money and resources). And…that's it! Pick one of the many other things that are much more worth worrying about.

If you want to get educated on the subject of engine oil for old cars, read this. Here's a nice "money quote" from it: The addition of extra ZDDP usually results in reduced cleanliness, higher engine temperatures and more deposits. Some studies have shown that going past 1400 ppm of phosphorus will increase wear over the long term, and going above 2000 ppm will begin to break down iron and result in camshaft spalling.

Longer, ranty version:

Science is wonderful, but it has its limits. For example, it stands absolutely zero chance when pitted against mythology handed down through generations from father to son and baked to impenetrable hardness by endless repetition as "common knowledge" in forums on the internet. Everybody knows your old engine will grind itself to death unless you add this additive (no, wait, that additive! No, you're both wrong, it's this other additive!) to your oil, or always only ever use this specially-formulated oil (no, no, not that one, you gotta get this expensive stuff from a special "dealer!") because the big bad government made the oil companies take out (no, wait, it was GM! No, it wasn't, it was the API! You're both wrong, it was Honda!) the zinc (no, dummy, it's the phosphorus! Shut up, you're both wrong again, it's ZDDP!).

Never mind that zinc antiwear additives are still present in current regular motor oil, but yesterday's very high levels have been functionally replaced by other chemistry that does at least as good a job.

Never mind that the current API engine oil tests really, truly, actually do include flat-tappet engines (two different ones!).

Never mind that the sudden surge in tappet failures within recent memory is directly attributable to the sudden and near-complete outsourcing to China of a giant swath of aftermarket lifters.

None of that matters, because everyone with an internet connection is a qualified tribologist and petrochemist.

In the vehicle lighting technical standards and specification world where I live professionally, we have our list of myths and half-understood bits of information that we roll our eyes about people swearing it's gospel truth right out of the Bible.

The oil people have the same tribulation: the general public reads a well-intentioned but out-of-date, incomplete, and oversimplified article, think they've understood that they have to use a high-ZDDP (zinc/phosphorus) oil in their old car, and then go shouting it all over the internet, whereupon someone else goes "Hey, yeah, I read the same thing!" and the myth gets amplified.

The evolution of engine oil antiwear chemistry did not start or end with Zinc, Phosphorus, or ZDDP. Don't worry/be happy about it unless worrying makes you happy, in which case don't be happy…worry!

Some people get a warm fuzzy by paying $10 for a quart of fancy-brand oil and pouring it into a car that doesn't need it…fine, if that makes their socks roll up and down; life is short and people should do what makes them happy.

For vastly most of us, there is no sound reason, need, or benefit to seeking and paying for specialty boutique oils. The lowest-performing oil on the shelf today is light-years ahead of the best-performing oil on the shelf when the Slant-6 was in production.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I agree with everything Dan said on this topic.

Now, let's move on to platinum cupro-iridium cosmotron split lead spark plugs. With those babies, you can easily pick up 50HP ad 15MPG.....if you have a proper set of mufflers.

Sounds like Dan and Greg think we could stick with fermented dinosaurs for a lubrication source, of which I agree. Although, synthetics do have their place, it's just not a "mandatory" thing that we have to use them in everything.

Oh....and Greg? You sure your not exaggerating a little bit with that 50hp claim?

Just my 2-pence.....Roger