Service intervals?
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Cross-Country
Joined: Jan 2006
Posts: 79
Likes: 3
From: PNW
Service intervals?
My 2018 6.7 SRW is approaching 60,000 miles, I bought it with 15,000 miles on it. Always changed the oil and filter every 3000 miles, fuel filter every other oil change. When should I change out the other fluids?
Fleet Mechanic
Joined: Jan 2015
Posts: 1,377
Likes: 291
From: SE Michigan
You should be performing transmission drain & refill every 35K miles or so (install a pan with a drain plug, like the PPE). Also should be doing doing rear differential fluid change (again, PPE pan with a drain plug), front differential fluid change (R&R with a hand pump), and transfer case fluid R&R at the same time. A complete brake fluid change is good around the same time as well.
FYI: You wasted a bunch of money doing oil changes every 3K miles. A BUNCH.
FYI: You wasted a bunch of money doing oil changes every 3K miles. A BUNCH.
Hotshot
Joined: Mar 2017
Posts: 10,136
Likes: 1,361
From: Chaz
Coolant and brake fluid, due to time.
Would be a good idea to do the rest of the driveline too.
3,000 is too early on the oil. I would extend the fuel filters too. It doesnt hurt to do anything early but no reason to open them up and risk contamination if not needed.
Would be a good idea to do the rest of the driveline too.
3,000 is too early on the oil. I would extend the fuel filters too. It doesnt hurt to do anything early but no reason to open them up and risk contamination if not needed.
Lead Driver
Joined: Nov 2005
Posts: 8,442
Likes: 4,945
You obviously have too much time on your hands, and money too.
I suggest you read the owner's manual for the maintenance schedule.
You really can't go wrong doing it by the book.
Hotshot
Joined: Jul 2013
Posts: 14,211
Likes: 2,170
unless we are on the severe duty schedule.....severe duty = towing or high idle time or lots of stop and go driving ( metro driving with stop signs or traffic lights every other block, etc).
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Cross-Country
Joined: Jan 2006
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From: PNW
So 2500 of the 3000 miles I’m towing a 6500 pound TT, rest of the time is city with a few 50-75 mile trips tossed in. I can stretch out the oil changes to 4500 I guess. Sounds like it’s time to change/flush whatever’s wet.
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Lead Driver
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From: Itinerant
You should be performing transmission drain & refill every 35K miles or so (install a pan with a drain plug, like the PPE). Also should be doing doing rear differential fluid change (again, PPE pan with a drain plug), front differential fluid change (R&R with a hand pump), and transfer case fluid R&R at the same time. A complete brake fluid change is good around the same time as well.
FYI: You wasted a bunch of money doing oil changes every 3K miles. A BUNCH.
FYI: You wasted a bunch of money doing oil changes every 3K miles. A BUNCH.
Lead Driver
Joined: Nov 2005
Posts: 8,442
Likes: 4,945
As I said, follow the owner's manual, save you time and money.
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,235
Likes: 753
From: Houston, Texas
Originally Posted by linedog
So 2500 of the 3000 miles I’m towing a 6500 pound TT, rest of the time is city with a few 50-75 mile trips tossed in. I can stretch out the oil changes to 4500 I guess. Sounds like it’s time to change/flush whatever’s wet.
Every 5,000 miles- Oil and filter change
Every 10,000 miles- Fuel filter change
Every 15,000 miles- Air filter check and change
Every 30,000 miles- Transmission pan and filter service
This type of service interval has kept my personal vehicles, fleets, and individual customer vehicles running and only coming to my shop for maintenance or something else.
One specific reason why I tell my customers 5,000 miles on diesel oil changes is because of fuel dilution. Part of the regen process is over fueling this time on all 8 cylinders not just the cylinders 7 and 8 on the 6.4 Powerstroke. Fuel can sometimes dilute into the oil and the oil isn't exact how it was designed anymore. Over time, this leads to bearings and critical engine components slowly wearing to the point of failure. Oil changes every 5,000 miles are cheap compared to the cost of a new long block from Ford, not to mention the labor to R&R.
Tuned
Joined: May 2010
Posts: 488
Likes: 129
From: Pleasanton, CA
I lean more toward longer intervals especially when using synthetics. Sure you can change oil, fuel filters, driveline fluids every 1000 miles if you wish but my feeling is technology wins as usual and there is no need to do it at shorter intervals unless you live in extreme, cold or hot maybe dirty, environments. We are not talking old toilet paper roll oil filters or conventional single weight dyno oils.
IMO at the minimum follow the manufacturer recommendation for change intervals and use synthetics.
Mike
IMO at the minimum follow the manufacturer recommendation for change intervals and use synthetics.
Mike
Moderator
Joined: Jul 2010
Posts: 12,049
Likes: 1,546
From: Media PA
You're not wrong for doing things the way you're doing them. Here's what I recommend for every customer and practice myself for all 3 of my diesel trucks:
Every 5,000 miles- Oil and filter change
Every 10,000 miles- Fuel filter change
Every 15,000 miles- Air filter check and change
Every 30,000 miles- Transmission pan and filter service
This type of service interval has kept my personal vehicles, fleets, and individual customer vehicles running and only coming to my shop for maintenance or something else.
One specific reason why I tell my customers 5,000 miles on diesel oil changes is because of fuel dilution. Part of the regen process is over fueling this time on all 8 cylinders not just the cylinders 7 and 8 on the 6.4 Powerstroke. Fuel can sometimes dilute into the oil and the oil isn't exact how it was designed anymore. Over time, this leads to bearings and critical engine components slowly wearing to the point of failure. Oil changes every 5,000 miles are cheap compared to the cost of a new long block from Ford, not to mention the labor to R&R.
Every 5,000 miles- Oil and filter change
Every 10,000 miles- Fuel filter change
Every 15,000 miles- Air filter check and change
Every 30,000 miles- Transmission pan and filter service
This type of service interval has kept my personal vehicles, fleets, and individual customer vehicles running and only coming to my shop for maintenance or something else.
One specific reason why I tell my customers 5,000 miles on diesel oil changes is because of fuel dilution. Part of the regen process is over fueling this time on all 8 cylinders not just the cylinders 7 and 8 on the 6.4 Powerstroke. Fuel can sometimes dilute into the oil and the oil isn't exact how it was designed anymore. Over time, this leads to bearings and critical engine components slowly wearing to the point of failure. Oil changes every 5,000 miles are cheap compared to the cost of a new long block from Ford, not to mention the labor to R&R.
) on the newer trucks with the 9th fuel injector after the engine so far as fuel dilution goes affecting oil change mileage? I would think dilution should be much less of a concern with the current setup. I’m only at 19K on the truck currently but we have a trip to IN coming up soon and that will push my change interval to about 7700 miles post trip and I am planning to also do the fuel filters then too (approx 20,500 miles then). All of my fuel is bought at high volume truck stops. Using Motorcraft filters and Shell Rotella T6 5W-40.
Last edited by WE3ZS; Oct 22, 2025 at 11:10 AM.
FTE Leadership Emeritus
Joined: Sep 2003
Posts: 12,235
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From: Houston, Texas
Originally Posted by WE3ZS
I have been going 7500-ish miles (between trips as close as I can) with my ‘24 F-450 that sees most of its miles with the big fiver in tow, last change was slightly over my target mileage but the OLM was still at 15%. What is your opinion (I do value it! ) on the newer trucks with the 9th fuel injector after the engine so far as fuel dilution goes affecting oil change mileage? I would think dilution should be much less of a concern with the current setup. I’m only at 19K on the truck currently but we have a trip to IN coming up soon and that will push my change interval to about 7700 miles post trip and I am planning to also do the fuel filters then too (approx 20,500 miles then). All of my fuel is bought at high volume truck stops. Using Motorcraft filters and Shell Rotella T6 5W-40.
) on the newer trucks with the 9th fuel injector after the engine so far as fuel dilution goes affecting oil change mileage? I would think dilution should be much less of a concern with the current setup. I’m only at 19K on the truck currently but we have a trip to IN coming up soon and that will push my change interval to about 7700 miles post trip and I am planning to also do the fuel filters then too (approx 20,500 miles then). All of my fuel is bought at high volume truck stops. Using Motorcraft filters and Shell Rotella T6 5W-40.
