The Oil Filter Thread
 

I know a popular upgrade to the Miata oil filter is the one off the Millennia. So a while back I was in my local NAPA asking questions about oil filters and the guy kept referring back to this book. What’s that book? I asked. He said it was NAPA’s Filter Reference Guide. It covers just about everything made.
With this guide filters can be looked up many different ways, but the one that makes sense for us is the page that has all the 20x1.5mm thread pitch for our cars. This page lists most of the important features including dimensions, O-ring size, the bypass psi, etc. Listed below is the page and highlighted are some of the other possible choices that would fit a Miata. I choose everything from the stock Miata filter up to the largest choice available to fit with an oil cooler sandwich adapter. So depending how much room you have to work with you can choose a filter that has more media and still uses the same bypass and micron size.
You can get the micron filter size by taking the filter part number from the reference guide and going to the Wix Filter site. By putting in the part number, Wix will list the same filter info plus how many microns down it will filter to. Armed with a larger selection of part number choices, this means more choices in brands NAPA silver, Gold, Platinum, Wix, Amsoil, Mobile One, etc.

https://www.miataturbo.net/attachmen...ine=1359340189

Here's the list from the guide.
https://www.miataturbo.net/attachmen...ine=1359340189

Here's what the sizes look like:
https://www.miataturbo.net/attachmen...ine=1359340189
https://www.miataturbo.net/attachmen...ine=1359340189

Now, the exception is the filter on the right, the 551318. This filter is almost the same as the others except for the by-pass, it takes 4 more psi to make it work (16 psi). This is the filter I will be using and I believe that the difference in by-pass pressure shouldn't be an issue. I hope this info helps, thanks for looking.
Cheers,
-JB

Interesting. Any clearance issues with the big filter on the right?

Holy shit that's a giant filter.

I still haven't used anything beyond the OEM size. I need to look into this next time I do a change. I think I want 1347, or the 2nd one from the left.

The one on the far left is OEM size, yes?

None, although it goes in and out in these space next to the alternator.
Here's the stock one:
https://www.miataturbo.net/attachmen...ine=1359341962
And the 551318
https://www.miataturbo.net/attachmen...ine=1359341962

Is it the angle of the pic or is that freaky close to hitting at the end? Looks like at that angle if the motor mounts allowed any movement that thing would hit.

Edit: Also I like the one second from the right. Looks to be similar size to what you used with a little bit more clearance for oil cooler sandwich plates being thicker or other things. #1626?

Did the rx8 filter come up in this? The rx8 filter is a touch longer than the miata one, but with a much higher bypass pressure. So it basically starts filtering the oil sooner during cold start. The bypass basically defines the max pressure differential allowed across the filter media. As long as the whole filter was taken into consideration when the stiffer bypass was added in it shouldnt cause an issue. Though I'm assuming that on a relatively clean filter on the miata the bypass will be closed, and that you change your oil filter regularly. If you get the filter really clogged up, increasing the bypass pressure could potentially cause a lower pressure issue, but it would at worst be the difference in bypass pressures between stock and your filter. If 4 psi is enough to kill your engine then your oiling system was pretty marginal anyways.

Also, from what I've seen, cars that come from the factory with higher flowing fuel systems use higher bypass filters. The rx8, subarus, some WV all have very high flow pumps, and they all have very high bypass pressures in the filters, hell the 1.8T wv engine has a 33psi bypass.

There's about 3/4" clearance. I would think that would be plenty. If I saw paint rubbing on the filter, then I definitely would choose a shorter one.

Nice to hear that 4 psi is no big deal. It's a new motor with a Boundry pump. The ref guide goes by part number. One section gives a general brand like Ford, Mazda, VW, etc. There wasn't a section to look up a year model car. Different book I suppose.

Let us know if the paint scratchs. Comp mounts? Maybe a vertical pic?

My filter is that tight in there.

Subscribed. I always just used PureOne Millennia filters with a rare earth magnet stuck on the end.

I have a shot from above but it really doesn't show the gap. Too much stuff/manifold in the way. I recommend buying 2 or 3 choices and see which one fits best for your set up. Then just return the ones you didn't like. I got 8 of them here and 7 are goin back.

For some time i use a Opel(GM) oil filter that was bigger than the mazda OEM, right at the star the oil pressure gauge read less pressure, than with the mazda OEM

1083 is 21 microns
1344 is 21 microns
1347 is 21 microns
1626 is 21 microns
7356 is 21 microns
1318 is 21 microns
1365 is 21 microns

Wow. I'm running the PL14459 which crosses to a 31334 Napa. Fits with the factory brace.

Oil Filter Height (Inches) : 3.194"
Oil Filter O.D. (Inches) : 3.252"

The drainback valve is 9-11 PSI. Been working fine on my car, cold start knock kept to a minimum. The PureOne Purolator is 20 micron.

Edit: Uh, might be a newb question, but the 551318 is coming up as a fuel filter in searches. Will this work as well with oil? Nevermind

Thanks for all this info. I was just wondering before last weekend's oil change what larger filters would fit.

I don't know, the "L" in the category is for lube. Try the cross reference with just the 1318 number.

Found it. Napa Gold 1318 crosses to Wix 51318 and has listed applications of certain John Deere Loaders and Yanmar Marine Engines. Sounds like a HD bugger. Purolator does not have an interchange. Seems it's not a terribly common filter.

The 1216 cross to a Wix (bet you can't guess) 51216 and lists some of the Eagle DSM cars, the 91 Dodge Monaco :giggle:, and 87-93 Jeeps, probably depending on equipment. This should be on the shelf most errywhere.

The PL14459 (Wix 51334) is shorter than the second one from the left, but just skinnier than the one second from the right. It's the filter for any year Acura Integra and numerous other import products.

This is the fitment that I used to use on my turbo '92, mostly because after I sold my Integra I had a filter left over, and I realized that it fit the Miata nicely. I'm pretty sure that filter was spec'd on all of the Honda b18 series engines.

What makes a bigger filter better? I was surprised to find the same filter is used for a turbo 2.5l Subaru as our little 1.8. My new Nissan 4.0l v6 uses one that is only .59" taller with the same OD and it's even good for 7500m OCI. Are there any UOA reports that show a bigger filter provides better or longer lasting filtration?

As far as I understand a larger filter will make no difference from a performance standpoint. Where it does make a difference is extending your OCI for particulates. More 20 Micron filter material is more that can successfully filter before diverting all oil to bypass.

My POV is that it won't hurt, and the larger filter costs virtually the same as the smaller one. I believe the OE Miata filter is spec'd at 40 microns (at least in a Purolator). Upgrading to any of these filters will give you better filtration.

The best filters I've found through research are either the Amsoil or the Royal Purple filters with synthetic media. They are also right about $15-$20 each almost regardless of size. The Purolators I've found to be the best bargain. $5, 20 micron filtration, good case coating for grip, and readily available. Although they're now owned by Bosch, and I'm not really crazy about Bosch. Never got a good Bosch O2 sensor, and never get any of their plugs unless they were OE for your vehicle.

Wix cost a little extra, but are always high quality. IIRC, Napa Gold is whitebox Wix.

Edit: Oh, and it lets you put more oil into your system. More oil acts as a larger heatsink and could lead to lower oil temperatures, as well as the extra wear additives provided in the extra oil further extending OCI's.

Amsoil makes a standard and a larger filter for the Miata.

I wouldn't assume a larger filter has more filtration media, not without cutting them open. I don't see anything on Purolator's site that states the PL14612 is a 40 micron filter. But that might be because all Purolator oil filters are 20 micron with the PureOne line catching more debris than the standard line.

If you're concerned about oil temp install a cooler, a bigger filter won't help with that.

Please post up your UOA results showing a difference in wear additives and contamination from running longer OCI intervals on stock vs larger sized filters.

I'm envious of those of you with convenient Napa locations, I use Purolators cause they are a great filter, reasonably priced and convenient. There's an Advanced in the same plaza as Oilmart and the happen to stock them.

Don't have any UOI's as my car burns a quart right about every 1000 miles.

https://www.miataturbo.net/attachmen...ine=1361051365

Excuse the cell phone pic. They were getting antsy at the Pepboys. It said 40 micron on the 14612 as well. Went with the PL14459 again, as they didn't have the interchange from the Wix 51626 on the shelf.

Edit: Just saw that another pepboys does have it on the shelf. PL14619 will try exchanging on the way home tonight.

Thanks for the pic. It would be really nice if they published this info on their website instead of trying to be deceitful and only listing the better specs of a pl30001.

So I'm going to do my first oil change on my car after its 5,000km from Vancouver to Hamilton (3,100 Miles) despite being all highway at 80mph for the duration of a tank of gas a number of times in a row. I'd really like to try the large filter for a bit more oil capacity. Is anyone still using the big filter without issue? How well does the anti drain back valve work for the oil system? Diesel fuel doesn't get as hot as engine oil can. I wonder if the seals and such are happy at 200+ F.

I've used the Donaldson P551318...well for its intended purpose as a fuel filter. Never considered using it as an oil filter. It lists as a 9 micron filter per Donaldson's specs https://dynamic.donaldson.com/WebSto...63&item=742494

WIX lists it as 10 micron Wix 33403 & Napa 3403 Fuel Filter: FleetFilter Secure Store - Wix, Fram, Baldwin, Luberfiner

Filter Bags | Micron Size Comparison Chart | Clearstream Filters Inc. This is a handy reference chart for micron sizes.

My UWAG (uneducated wild ass guess) is that if a filter can catch particles down to 9 or 10 microns it would have a shorter service life vs a filter of the same size that can filter to 21 or even 40 microns. It would be interesting to see the particle count in the oil between 21 micron and 9 micron. My bet is there many more 9 micron particles and the larger 551318 filter might not have a much longer service life over the stock filter. The oil will stay much cleaner. I would love to do oil samples back to back with the same oil, change interval and driving conditions between a stock filter and the 551318. Then again I'm sure I will burn it off faster than anything to really matter.:facepalm::rofl:

I ended up going with the Purolator PureONE part # PL14619 nice compromise for cost vs quality. I buy'im by the case.
Cheers,
- Jeff

My UWAG would be that, as lubricating oil has a much higher viscosity than diesel fuel, a filter designed for diesel fuel would present a much greater restriction to flow under normal operation than one designed for engine oil.

Do diesel fuel filters even have internal bypass valves? If so, it's gonna spend a lot of time in bypass. If not, your oil pump's pressure reg valve will, and flow (especially when cold) will be greatly reduced, which is a far worse prospect.


Either way, I've never had a problem using oil filters to filter my oil. I'm not gonna be the first person who tries using a fuel filter in this application.


Just a WAG.

+1 for the pureONE. Loved the grippy case.

Eunn, will 7/8-14 still spin on the 20x1.5mm that we normally use? To the filters credit it does flow 12 gpm. I think it was Ford that has a by-pass filter system for their diesels. It was a really small micron, like 2-4.

I had to get that model number pure one for the wrx because I ran out of RX8 filters. Got to make another order with mazda to get a case of those RX8 filters since they're great on all my cars.

Do not use a diesel fuel filter for oil. It will destroy your engine.

Pretty much.


You know how sometimes you get an idea, and wonder "why, in the hundred-year history of this technology existing, with billions of dollars being spent in R&D at facilities all over the world, has nobody ever thought to do this obvious and brilliant thing?!"

Usually, it's because it's a really terrible idea.

Diesel filters clog and are replaced regularly in my business. The symptom is low machine power due to running lean. There is no bypass. What happens when your oil flow becomes similarly restricted? The engine doesn't slow down, but the oil does.

Additionally, diesel fuel filter media is often designed to absorb any water present and to swell as it does. This swelling also reduces flow (design feature) to let you know you have a fuel problem that should be attended to. Try that with your oil supply and report back to us.

For the record I was never intending to use a fuel filter for my oil. I was curious if 2manyhobyz ((or anyone else) had any luck good or bad with the 551318. *EDIT I guess I did say I'd like to try the larger filter. I should have said A larger filter before digging into that 551318 filter specs as a sidenote*

I couldn't tell you. I would assume so since you have a picture of the filter I had posted installed? I was under the impression you had run that filter. EDIT I realize that a P551318 and napa 551318 (now 1318) are two very different filters.

Diesels run lean all the time. It's called part throttle and idle. Also how often is this happening? I used to manage a fleet that had 30+ diesel engines trucks and highly abused off road equipment and I never had a performance problem unless a filter was neglected or bad fuel was pumped into the tank.

You do realize that there's a difference in viscosity between diesel #2 and 5w30, right?


By all means, do the test and report back on the results. I'm genuinely curious to know whether my intuitive perception has any grounding in reality on this one.

:jerkit::fawk: Yes. You do realize I've admitted to making a mistake which you will see if you read post #35.

Your Ninja-editing skills serve you well. But may the fleas of a thousand camels infest your armpits.

Check the times when edited and when you posted.

You have no idea as to the depths of my laziness and apathy. Hours can pass between the time I click "reply", subsequently get distracted by shiny things, cook dinner, watch some TV, argue a bit with the missus, and finally come back to the PC to find that I forgot to hit the "submit" button.

I consider this a superpower.

It's only a super power if you can subsequently get the security token error and lose all of your post.

I did have the napa 551318 on the car and it was only about a half inch of clearance. I would have continued to use it but I wanted to upgrade to their silver or gold line which is a better filter, but it is a bit of an odd ball and they didn't produce in their better lines. So the Purlator ended up the best compromise for me.

When the new high pressure diesel injection (common rail or whatever terminology you prefer) arrived on the scene, the particulate size the filters allowed to pass was significantly less and new machines would stop working and the older ones would keep going. Most of my customers have lousy fuel handling practices and had problems with mechanical injection engines anyway.

The solution for that was adding a prefilter/water separator/fuel heater. It had to be done on Dozers and excavators since those machines get filled from a slip tank in the operators pickup and they don't always keep them clean. Filters out rocks, dirt clumps and small children. Helps to keep the fuel in good shape when its -40 below too.

Diesel Pro 243 Unheated Fuel Water Separator, 243050RLDAVK-0, Davco Mfg

Our solution is to advise them to put a fine filter on the hose from the portable tanks and to not pre-fill machine filters.

I wouldn't put too much stock in manufacturer "micron" specs unless there is a first pass efficiency attached. Amsoil is one of the few I have seen that provide that data:
https://www.miataturbo.net/attachmen...ine=1449948681

Technically a manufacturer can advertise a filter as "10 micron" even if it only catches 10% of particles that size.

I've always just used the Purolator Pure One PL14459. It's the one specified for the B6t and BPt motors found in mazda 323 GTX's. slightly bigger than the non turbo version specified in the Miata.

Ive used the PL14449 for years its also used on the Honda S2000 and is a typical upgrade for most honda engines that use a smaller filter.

https://cimg9.ibsrv.net/gimg/www.mia...5d73af8bb5.jpg
With my sandwich plate and half cut intake manifold brace a larger filter is easily added to my setup. I did some research using WIX's nice customizable database and found a filter that would better match the larger aftermarket sandwich plate.
The WIX 51347 was the clear winner. NAPA calls it a 1347 in the Gold brand. It's huge compared to the OEM with almost twice the media area.

Bringing this thread back from the dead. I found that a 2024 Honda Accord filter (any engine) is about 1 inch longer than the Miata filter with the same bypass pressure. It is a good replacement if you want a longer filter element.
Miata - https://www.fram.com/fram-ultra-synt...spin-on-xg6607
Accord - https://www.fram.com/fram-ultra-spin...-filter-xg7317

Increasing the bypass pressure is more important than capacity. Historically Honda specified a very low micron rating for their engines which is a move in the wrong direction for this application. It may actually offset any increase in flow rate from a larger element. For a high performance low service life application it would be desirable to have a high flow element in a sturdy canister with a reliable bypass design that is at a higher pressure.