Motorcraft Parts FAQ: 2017 F-350 6.7 Oil Filter, EGR Valve, Piston SR, Air Filters, and Catalytic Converter Rattle

Full disclosure: I'm not a mechanic. I'm the guy who buys components, checks incoming parts, and fills warranty returns because somebody (usually me) ordered the wrong thing. I've been sourcing and quality-checking automotive parts for 11 years now. I've made enough bad calls to build a library of lessons, so this FAQ is the list I wish I'd read before ordering Motorcraft parts or diagnosing that exhaust rattle.

Here are the questions I hear most often, with the answers I'd give you across a desk:

• Is the Motorcraft FL-2051S the right 2017 F-350 6.7 oil filter?
• Why does my catalytic converter rattle?
• Should I choose a Motorcraft EGR valve?
• What does 'piston sr' mean on a parts order?
• Is a 10x25x1 air filter a vehicle air filter?
• Can small shops order in small quantities?

Is the Motorcraft FL-2051S the right 2017 F-350 6.7 oil filter?

If you're talking about the engine oil filter, yes. If I remember correctly, the service filter is FL-2051S, but don't quote me on it—always check the current Ford parts catalog before you order. The 'S' matters. Sometimes people order the FL-2051 thinking it's identical, and it's not. I've made that mistake.

In my first year, I ordered 120 'compatible' filters from a cross-reference chart. The thread size looked right, the gasket looked right. What I didn't check was the bypass valve setting. Every filter went back. Cost me about $740 in freight and a week of a customer's downtime. From the outside, a filter is just a can with a hole in it. The reality is the media, the bypass valve, and the anti-drainback valve all have to match the oil pump and the engine's cold-flow behavior.

For a 6.7 Power Stroke, I stick with a Motorcraft filter. Not because I work for Motorcraft (I do, but that's not why), but because the filter is one part I'd rather not guess on. The whole oil system is designed around it.

Why does my catalytic converter rattle?

Short answer: it might not be the catalytic converter at all. I've had three 'bad converter' units come back to us this year, and two were heat shields.

People assume a rattle under the truck means the ceramic substrate inside the converter has come apart. That does happen. But before you buy anything, get under it and check:

• Heat shield on the converter or muffler
• Loose clamp or hanger
• Flex pipe touching the frame
• Flange bolts that backed off

A 2017 F-350 6.7 diesel doesn't have a gasoline-style catalytic converter in the classic sense. It uses a diesel oxidation catalyst (DOC) and a DPF. If the rattle is genuinely inside one of those, that's a much bigger repair. But 'inside the converter' is the last thing I assume now. The first time a customer told me the converter was rattling, I ordered a replacement before looking. Rookie mistake. It was a heat shield. That's the kind of miss that costs you time and credibility.

Should I choose a Motorcraft EGR valve over an aftermarket valve?

I understand the temptation. An aftermarket EGR valve can cost less than half as much, and if you haven't had a bad one yet, it's easy to think they're all the same. What I've learned is that the valve isn't just a mechanical part. It's part of the engine management system. The ECM watches the valve position, and the sensor curve has to match Ford's software.

People think an EGR valve fails because the part is cheap. Actually, the part is often the victim. Carbon build-up, oil consumption, and short trips make the valve stick. If you replace the valve without addressing the root cause, you'll be back in six months. I've tested aftermarket EGR valves that passed bench tests and still set a code on the vehicle. Put another way: a bench test doesn't simulate hot coolant, exhaust soot, and the Ford ECM.

If a customer wants the cheaper valve on their own truck, I'll install it. But I'll also record the mileage and keep the old part. That's not arrogance—it's protection. And if a supplier claims their part is 'identical to OEM,' I ask for test data. Per FTC guidelines (ftc.gov), a claim like that has to be substantiated.

What does 'piston sr' mean on a parts order?

In the metal parts business, 'piston sr' usually means a stock-replacement piston with a standard ring package. It's not a Motorcraft part number, and it's not a brand. I've also seen 'SR' used for 'single ring' and 'semi-rough.' That's why I don't trust abbreviations on purchase orders.

A story I don't tell often: in 2021, I approved a PO for 500 pistons labeled 'piston sr.' I didn't ask for the full Ford reference number. I didn't check the groove dimensions. The parts arrived with the wrong ring groove depth. We had already machined about 200 of them before someone measured one. That error cost about $3,100 in scrap plus a week of production time. (Note to self: always ask for the full part number, no matter how many times you've ordered it.)

If you're ordering pistons, use the complete part number or at least the engine code. 'Piston sr' is conversation shorthand, not a contract specification. And if a supplier says 'it's standard,' ask them to write the standard number on the PO. You'd be surprised how many different standards exist.

Is a 10x25x1 air filter the same as an automotive air filter?

No. Let me rephrase that: not the one you're thinking of. A 10x25x1 air filter is a common residential HVAC return filter—10 inches by 25 inches by 1 inch. It's for a furnace, not a truck.

People assume that if the dimensions fit, it'll work. The reality is that a vehicle air filter has to match the airbox sealing surface, pleat count, and media. On a 6.7 Power Stroke, the intake is tuned for a specific filter. A sloppy fit means dirty air, and dirty air on a diesel gets expensive fast. Air filter performance is tested under standards like SAE J726, which measure dust-holding capacity and efficiency. A furnace filter dimension doesn't tell you any of that.

I once quoted an aluminum housing for a '10x25x1 air filter' because I assumed it was some kind of panel filter for a custom build. It turned out to be a furnace filter. The customer had written the wrong part description. That mistake delayed their project by two days while we re-cut the housing.

Can small shops order in small quantities?

Short answer: yes, and you should. When I was starting out, the vendors who treated my $200 orders seriously are the ones I still use for $20,000 orders. Small doesn't mean unimportant; it means potential.

We don't automatically refuse low quantities. For standard filters, one box is fine. For custom stampings or CNC parts, the tooling cost is the real minimum. But if you're testing a design, a good supplier will work with you. What I'd avoid is a supplier who ignores you until you buy 10,000 units. That's not necessarily bad—it just means their process isn't built for you. Find someone flexible enough for a trial batch.

One caveat: small friendly doesn't mean small gets the same price as volume. Small orders have real setup, handling, and paperwork costs. What it does mean is the quote should be clear, the lead time should be honest, and nobody should make you feel silly for asking.