Deciding on which weight diesel oil for 2000 7.3L Ford Diesel

[Oillover]

I am concerned about engine life and quiet operation. Not what some one on the internet says.

But those are YOUR concerns.

OP wants to run a large diesel engine on the thinnest oil for the sake of fuel economy
For that, I think they should proceed accordingly....maybe even consider a nice 0W16.

After all, what do a bunch of engineers and heavy duty mechanics know about maintaining an engine?!
🤷‍♂️

 

[vincent714028]

I decided to use Rotella T4 10W30 and a Motorcraft FL1995 oil filter. I replaced the Wix fuel filter that was in there with a Motorcraft FD4596 which is the oem filter. I will let you know how it goes.

 

[Roost426]

15w-40

 

[Roost426]

I see you all are saying 15w40 but I hate thick viscosity oils. My dad ran castrol gtx conventional 20w50 in a 1991 toyota 4x4 pickup with a v6 engine. I thought he was insane. Still, he used it for over 200,000 miles till we sold it. I like the thought on the diesel engine running smoother and easier with the 10w30.

It's an old school diesel, 15w-40 is the preferred oil your manual's chart chart even shows for above 30 degrees which will be the vast majority of your use it looks like

 

[vincent714028]

The engine runs smoother and it spins up quicker when I start it. So far I'm happy I switched the oil weight to 10w30.

 

[Elgouyu]

My manual says I should use anywhere from 5w30, 10w30, to 15w40 depending on the temperature outside. I live in Alabama so I see anwhere from 15 degrees fahrenheit to 100 degrees fahrenheit. I am thinking 10w30 would be a good compromise. I want to run the thinnest oil I can for gas mileage without losing engine protection. I will be towing a lot but I will drive it only occasionally so maybe 5-10k miles a year.

Cheapest 5w-30 in winter, cheapest 15w-40 in summer.

 

[Bailes1992]

This was the most pointless of threads. OP had long made his mind up before even posting.

 

[SubieRubyRoo]

The smartest and most helpful statement here.

The way I chase fuel economy on my truck is with my right foot. I can easily get 1.5-3+ MPG better than anyone else who drives my truck for distance because of starting and coasting techniques, but especially with using minimal pedal pressure to maintain a constant speed. My '19 F150 SC 3.5EB I normally get 22.5-24mpg depending on headwinds and how much city driving. I let my wife borrow the truck and even to run to town and back she's dropped my average into the mid-low 21s or worse!

I agree with essentially everyone else in your thread here, OP- you're free to do what you want, but if you want another 200k out of your engine, you should go with a 15W40 on Ford's approval list. It's almost assuredly certain your truck's previous owner used 15W40, and hence why you bought it with 287k.

 

[02zx9r rev2]

The engine runs smoother and it spins up quicker when I start it. So far I'm happy I switched the oil weight to 10w30.

It has new clean oil in it, of course it will run smoother right now.
I must not have been in tune with my vehicles over the years, I’ve never noticed them spinning up quicker going from Xw20 to 5w30.

My opinion only, this thread needs to be closed. As many have said, numerous people have given him their recommendations that he asked for and he chose to go with his 10w30. Case closed

 

[MacManus99]

I must not have been in tune with my vehicles over the years, I’ve never noticed them spinning up quicker going from Xw20 to 5w30.

You're "in tune" just fine. You've never noticed it because it is imperceptible. The people who perceive this are perceiving a placebo effect.

I would honestly love to be proven wrong on this statement, but have yet to see any data that would do so.

 

[dnewton3]

We've had a 7.3L PSD and my neighbor had a 6.0L PSD. We both ran 10w-30 HDEO year round and had excellent wear protection as confirmed via UOAs. We tried both 30 and 40 grade, and decided the 30 grade made better sense in our situation.

The HEUI systems will respond better in cold temps to the 30 grade lube; it will indeed fire up a tad quicker, and most certianly will not "romp" at cold idle as much as with a 40 grade. Further, in really cold temps, the "spin up faster" is due to the pumpability of the lube; we all understand that. In a gas engine, it's not a bid deal, but with a C/I engine, it can be a very big deal in cold temps.

All that said, in AL were the OP is at, it's pretty much moot; he's not likely to see much distinction between the 10w-30 and 15w-40.

 

[Hasty66]

In my humble opinion as a former 1997 7.3L Powerstroke owner living in a southern climate (Texas), use 15w-40 oil. I did oil change intervals at 5k miles and it was running great when I sold it with over 200K in 2005. I used Rotella T4 or Valvoline Premium Blue with a Motorcraft FL 1995 oil filter. Wish I had kept that truck...

 

[Wizz]

15W-40. A lot of headroom for dilution and shearing.

 

[anderson]

15w40 for the win.

you better be joking about trying to get fuel mileage outta a 7.3 ford.
its gonna get what shes gonna get oil aint changing nothing

 

[MaxPF]

It has new clean oil in it, of course it will run smoother right now.
I must not have been in tune with my vehicles over the years, I’ve never noticed them spinning up quicker going from Xw20 to 5w30.

My opinion only, this thread needs to be closed. As many have said, numerous people have given him their recommendations that he asked for and he chose to go with his 10w30. Case closed

This thread needs to be kept open for that reason. It's an excellent example of confirmation bias.

 

[SubieRubyRoo]

My manual says I should use anywhere from 5w30, 10w30, to 15w40 depending on the temperature outside. I live in Alabama so I see anwhere from 15 degrees fahrenheit to 100 degrees fahrenheit. I am thinking 10w30 would be a good compromise. I want to run the thinnest oil I can for gas mileage without losing engine protection. I will be towing a lot but I will drive it only occasionally so maybe 5-10k miles a year.

7.3 HEUIs are NOT easy on oil and are very shear happy since the oil is used to generate 3000+ psi in the pump. IMHO it’s a false economy to try to use a 30 weight to “gain” fractional amounts of mileage, especially when towing. If you want to maximize mileage, you’d be best served to make sure your intake & exhaust tracts are less restrictive than stock, and maybe add an aftermarket intercooler which will not only improve power (especially when towing), but will also reduce restriction in the intake and make sure you're maximizing the flow of air through the engine.

7.3 parts aren’t getting any cheaper, so if it were mine I’d definitely run the 15w40 with some 4-5k UOAs to make sure: 1. You’re not shearing it out of grade, and 2. Not loading the oil up with abrasive soot. Then adjust your OCIs according to what the oil can handle with your engine and usage habits.

 

[SubieRubyRoo]

I think people should use the thinnest oil that the owners manual will allow. There are a few posts from a few years ago where Caterham says he tries to use the thinnest oil he can when deciding what to use in his vehicles. I like the idea for the fuel economy, for the reduced cold starting stress on the engine, and a slightly faster rev when giving the gas to the engine.

The engine’s not going to rev faster if you’re not achieving the MOFT required to separate parts, and the crank and rods are riding directly on the bearing material instead of on a hydrodynamic layer of oil…

 

[Redhawk454]

7.3 HEUIs are NOT easy on oil and are very shear happy since the oil is used to generate 3000+ psi in the pump. IMHO it’s a false economy to try to use a 30 weight to “gain” fractional amounts of mileage, especially when towing. If you want to maximize mileage, you’d be best served to make sure your intake & exhaust tracts are less restrictive than stock, and maybe add an aftermarket intercooler which will not only improve power (especially when towing), but will also reduce restriction in the intake and make sure you're maximizing the flow of air through the engine.

7.3 parts aren’t getting any cheaper, so if it were mine I’d definitely run the 15w40 with some 4-5k UOAs to make sure: 1. You’re not shearing it out of grade, and 2. Not loading the oil up with abrasive soot. Then adjust your OCIs according to what the oil can handle with your engine and usage habits.

I have to ask, how do you avoid loading the engine with abrasive soot?

 

[SubieRubyRoo]

I have to ask, how do you avoid loading the engine with abrasive soot?

Frequent oil changes and things like bypass filtration systems

 

[ESP9935]

My manual says I should use anywhere from 5w30, 10w30, to 15w40 depending on the temperature outside. I live in Alabama so I see anwhere from 15 degrees fahrenheit to 100 degrees fahrenheit. I am thinking 10w30 would be a good compromise. I want to run the thinnest oil I can for gas mileage without losing engine protection. I will be towing a lot but I will drive it only occasionally so maybe 5-10k miles a year.

5W-40 -- T6, Delo Syn, whatever... FTW