Oil filters

It seems to me that oil filters keep getting smaller in relation to the size of the engines. A friend said this is true and is because modern motors do not suck outside air into the crank-case like the old ones did and therefore avoid the dirt that would come in with the air.

Questions: Are filters getting smaller?

If so, is my friend right about the reason?

Ironically, many cars in the 1940’s and 1950’s did not even have oil filters and these cars had open crankcase ventilation. There was a road draft tube leading down under the car and an oil filler cap that had a wire mesh filter. The air was sucked in through the oil cap and the partial vacuum created at the base of the road draft tube sucked out the blowby from the pistons. I think your friend’s reasoning is incorrect. In fact, cars since 1962 have had the closed crankcase ventilation system. I think that the filter size has more to do with the amount of room in the engine compartment and the fact that today’s engines run much cleaner with fuel injection rather than carburetion, so that the larger filter size isn’t needed.

Oils (dino and synthetic), fuels and filter construction have changed a lot over the past 20 years. The physical size of the filter is not an indicator of how well it works.

Some filters are smaller than they were in days gone by. I don’t think they work any less well, however, and I don’t think airborne dirt is the reason for the change in size.

Automotive engineers know how much filter area they need to keep the oil clean. If smaller works, why not?

Filters are probably made of better filtering material now requiring less space to filter properly.

Engines burn far, far cleaner now. And oils has evolved greatly.

Filters have shrunk dramatically, but engines today last 2-1/2 times as long as they used to. Go figure.

I used to get the cheaper model filters from NAPA and the one for my 87 MAZDA truck was really small. I got a kick out of that.

Some people are just obsessed about the size of their … um … oil filters.

Seriously, engines have gotten a lot smaller too, not just the oil filters. Also, if you compare the size of different brands of oil filters, you will find different sizes, but they all meet OEM specifications. The Honda brand oil filter for my car is smaller than the Fram filter for my car, which is smaller than the Purolator filter for my car.