Why are there so many different kinds of oil filters when many or most have the same attachment thread and the same diameter gasket?
Different manufacturers have different standards for flow capacity, filtration, backflow valves, etc. A large engine will need more flow capacity than a small engine. They also don’t all use the same viscosity oil.
Is it true that most oil filters have the same attachment thread and the same diameter gasket?
I find that hard to believe based on my own experience - but I’m not a mechanic nor do I pretend to be one.
There is a lot of commonality with the threads (still not all are the same thread), but gasket diameter I don’t think is the same everywhere. For example, the Ford Motorcraft 820S filter gasket I think is larger than the one for the Subaru.
The Toughguard for my 2002 Sienna and the 1989 Dodge Caravan I had before, call out the same exact filter. No reason they couldn’t, but it was a minor surprise.
The one interchangable filter I remember was for the Chevy small block, when GM went from a large (1 qt) one to a smaller one (1/2 qt?). Space permitting, I’d put on the larger one.
It’s called Shelf Space…Every new filter part number requires sellers to, collectively, stock millions of new filters…Filter manufacturers love it…Also, you can’t expect prima-donna engine designers to use an existing filter or belt. That’s just not how the game is played…On popular engines, there are usually several filters that will fit, the only difference being case size…If every parts store in the country must buy a case of new filters, that’s A LOT of filters…
There are many variables to the oil filter.
Thread form is generally either 3/4"x16 TPI or 20mm metric. So there are 2 common configurations.
However, the depth between the gasket face is start of thread varies. Lets say there are 5 common configurations.
The gasket diameter varies. Lets say there are 5 common diameters.
Anti-backflow valve can be present or not. 2 configurations.
Internal bypass (pressure relief valve) pressure varies. Lets say there are 5 common psi settings.
Media area varies. Lets say there are 5 common values for square inches of filter media.
Diameter of the shell varies. Lets say there are 5 common diameters.
Length of the shell varies. Lets say there are 5 common lengths.
With just these criteria, there are:
2552555*5=62,500 possible configurations of oil filters using the most common values.
Of course, there are not 62,500 oil filters on the shelf. So the question you should really be asking is why are there so few oil filters?
Back in the good-ol-days…Ford had ONE filter for ALL their vehicles…From the Pinto with the 2.3l 4-cylinder thru the F-350 with a Large V8.
Yes and back in the “even-better-ol-days” many automobiles either didn’t have an oil filter or the oil filter was an option. My 1947 Pontiac didn’t have an oil filter. I had a 1955 Pontiac that I bought used and it didn’t have an oil filter–it was an option on Pontiacs that year. My parents bought a new Rambler in 1960 and it didn’t have an oil filter. The dealer installed one, but it was a partial flow filter–not all the oil went through the filter. I guess it was better than nothing.
Underhood packaging is also a factor in oil filter sizes. It’s getting so that every cubic mm under the hood is filled and the canister has to fit the hole and be removable.
Mike commented about the old days. I still have all my old flter wrenches, and the canisters were huge by today’s standards. Over the years I had to keep buying smaller and smaller wrenches. The canister on my current filter looks about the size of a Dixie cup. Of course the filters of old also had a lot more stuff to filter out of the oil. Today’s engines are far cleaner even as it applies to the oil.
Good question and the same thought can be applied to air filters, brake pads, tires. fuel filters and many more maintenance items.
There may be some merit to the present chaos in filter and other auto maintenance item design in that it permits easy technical advancements and cost reductions.
I have opened used oil filters to measure the filtration area to compare and then use the filter with the largest filtration area that fit our particular car at that time and have had good engine life with the reasoning being that more area results in less pressure drop across the filter and therefore less tendency to push dirt through the filter.
The game that auto makers play continues with insert type filters without the sheet steel housing but fit instead in a compartment that has a screw-on lid. We have different make 08 and and 09 GM cars that use these and would you believe that they are of a similar size but are not interchangable? Incredible!
A few years ago I wrote to the SAE to ask why there were so many different oil filter designs and asked if they could be consolidated to a few. Someone from Fram told me that at that time there were more than 200 oil filter types. I got a reply from the SAE. They said that was out of their area of influence, a complete copout in my view. I can think of no sane reason why oil filter types can not be consolidated into a dozen or fewer.
I once replaced the small filter on a Dodge Shadow with a much larger one from a Ford, probably a PH8. I figured, more oil=better cooling. It spun right on, there was room for it and the gaskets appeared to be the same. The only problem was it had low oil pressure once it warmed up. The right filter fixed it.
Just to throw some more “stuff” into the mix, my wife bout a new Honda Civic back in 93. I used the stock size aftermarket filters the first year, but a year later, when I went to do another oil change, the filter number had been changed to a smaller size. I kept using the same filter but I had to check my book for the filter number before going to the store.
I noticed the same thing might have happened with our 86 Toyota (used), the filter on it was slightly larger that the one listed in the parts book at the store.
Now with the Nissan truck I bough new in 97, the aftermarket filter was also smaller than the OEM at the time, but that was welcome as there was no room to get at the OEM, it took forever and a lot of disassembly to get it out. The smaller filter fit right in and is much easier to get in and out.
BTW, I go with the smaller filters now as they do build up oil pressure faster and cars don’t need that much filtration any more.
As late as early 2000s Honda cars all took the same oil filter.
Has any one ever seen a modern oil filter without an anti-drainback valve? I haven’t.
This IS an old thread, but still very relevant.
I have taken care of 3 large families cars and a small business for 30 years.
There are a few variables that must be followed when trying to get a bigger volume filter for your car. (Stick with the OEM’s if you are under warranty.)
- Thread size (about 4 different ones currently used).
- Gasket size and type.
- Does the OEM have by-pass and relief valves?
- Case size…will it fit?
Many times the same engine is used in many different vehicles, and the manufacturer will use the same filter for all of them, based on the tightest application, no matter how much room there is. This makes the option of using a larger capacity filter, having a much greater amount of filtering media, open to use, if you have the room.