Why is is that diesel fuel filters need to be changed every 15,000 miles, but gas fuel filters seemingly go for eternity? I understand water is an issue with diesel, but 2 filters needing changed every 15k seems excessive.

I change both my filters every other oil change, so every 10,000 miles and I can feel the difference sometimes.

To your question - I don't know.

Diesel is not refined to the extent that gasoline is. Decreased flow from impurities is increased heat for a diesel. I'm sure a diesel mechanic could describe it better though.

My understanding is pretty much this, more impurities in diesel fuel to filter out.

You drive a Dodge Peppa which is all you need to know. Fords aren't that finicky.

So you’re saying Ford’s are built like [censored] with loose tolerance?

Diesel injection pumps on newer diesels are built with extremely close tolerances. Any impurities will screw them up.

Also.....

Diesel fuel attracts water in underground tanks. Water grows algae. Algae plugs filters.

Fuel filter changes on diesels are important, even more important is to use good ones, and do not pre fill them out of a can or something. I have seen fuel filters become more and more restrictive over the last 30 years to be good enough to protect today’s fuel systems. With the higher degree of filtration comes more frequent changes. The race for more power per cube, and the Govt’s push for reduced emissions, has made the need for higher injection pressures to do so, and to get there, very tight fitting parts are required, and any wear on them shows up fast.

Do then new ones have injectors?

Edit: I Iooked it up, they do

I feel like a bad dad.. I do mine every 20-30k

But I do drain water out every oil change

Better than me. I do it when the computer tells me to do it and I have never drained water.

Filters don’t need changing that often. People often think a filter stops filtering or something. Actually the opposite is true. The dirtier a filter gets the better it filters. Eventually it will get plugged up and not flow but the worst filtration your vehicle will see comes from a new filter.

I have a 19 power stroke and I changed the fuel filters for the first time at 40k miles. You made need to change them more frequently depending on where you get your fuel.

That Diesel Power is expensive I had no need for it that's why I went with a gas engine 1 ton.

hahaha...funny as hell but the truth is that if you drive a diesel and that filter gets clogged you will think you have blown you engine up with the lack of power it will have if it runs at all.......any make or model!

My ‘19 F350 calls for fuel filter change at 30,000 miles. I do it at 15,000, it’s cheap insurance. A fuel system replacement/repair could cost thousands.

Thank you, I agree I'm a visionary

I do my fuel filters every 10,000 miles. High pressure fuel systems on diesels are expensive, filters are cheap. Also as others have said, diesel tends to be dirtier anyway.

Diesel fuel is injected at 10,000-30,000 psi versus gas engines that may only inject around 10 to 100 psi.

Damn algae worms get me everytime!

since Diesel is a longer-chain hydrocarbon, it is not toxic to algae; gasoline is shorter-chain, and plenty toxic to most life forms.
Like Tbar says, lil-bit of water in the diesel is all that is needed for algae to thrive.

for example, paraffin wax is extremely long-chain hydrocarbon - even humans can eat the stuff and it will pass thru you without harming you.
Heck, they sell mineral-oil for oral use, to aid with constipation. long-chain too, not as long as paraffin.

diesel-treat or stabil-for-diesel has algaecides that reduce the issue - even then dead algae still will eventually clog filters.

I got some bad diesel once. While remodeling a fuel station, a sewer line was run to a diesel tank. I literally had shi**y fuel. There were a total of 3 trucks at the local dealer across the highway with bad fuel issues. The dealer that supplied the fuel made good on the repair and then some.

^^Have had it happen to me a month ago. Mule diesel. My fault for not changing the filter, and cleaning the water separator screen.

Same here. I was in the wholesale fuel/lubricant business for almost 30 years. Today's ULSD diesel fuels are far inferior to clear and LSD diesel fuels of yesteryear. So much so that refineries will add a lubricity additive back in to the ULSD fuel to help. Cetane levels also vary from batch to batch no matter what cetane levels the State of TX mandates. In light of this, I'm a huge believer in draining water as Bobo says, and using fuel additives that add more lubricity, keep injectors clean, and increase cetane.

Close, but not exactly. All filters are designed to work inside a "performance band". Most filter down to about 5 microns, anything less would be too restrictive and and cause reduced power, on the other end under performing filters allow too many particles to pass which can result in a failure as well. As some have stated, depending on the station and their tanks condition should impact your decision on how often to change them.