So after 10 years and 115K miles as the original owner of my 6.0, I said goodbye yesterday. It wasn't an easy thing to do. I know and like 6.0s, but I'm clueless about the 6.7 because I never dreamed I'd own one. Guess the head shrinker was right saying I have impulsive behavior. I wonder what that fruit loop is right about. But, moving forward, I have a couple questions.

I religiously added Lucas upper cylinder lubricant and a cetane booster to every tank of fuel in my 6.0 since the switch to ULSD. I felt it made a difference, and I never had an issue with my fuel system (other than a recurring issue with an aftermarket fuel pump manufacturer that will remain nameless). When my heads were pulled for studs at about 70k, I was told my internals were spotless...like the cleanest they'd seen. And that was with a modded/tuned truck since before 20K. What's the word on using additives with these motors? From what I have read, you want to break them in before adding anything? How long is that wait?

Also, my truck came with 20 in 275 Michelins. I'm probably looking to go to an 18 in wheel, so first are there any issues there? I was wondering what size tires these trucks can run without a leveling kit? I think the tires on the truck come out to like a 34.1 inch, and I'm looking to run something in the 35 inch range. Not looking to hurt fuel mileage and especially the truck's ride comfort. Rough ride was 90% of the reason I upgraded.

Thanks in advance.

 

Yes, lots of us run an additive in our trucks. Any of the ones from Ford's to Diesel Kleen to Stanadyne and a few others. As far as your tires, around here Nittos are quite popular. As for the leveling kit goes, someone else will chime in I am sure. I haven't dealt with any of those as I drive a dually.

 

I ran Cooper discovery STT's on my F250. Great mud and snow tire. Excellent off road and towing.

 

Thanks. I was running Diesel Kleen in my 6.0.

I'm well versed in tires, just not how different sizes fit on these trucks. I looked for a tire fitment guide, but I didn't find one.

 

To each his own,
I have worn out ford deezles too and never put an additive in any of them 7.3's, 6.0's, or two 6.7's except two times

one time on a trip up north in the cold and put some of the antigel diesel kleen from walmart... because we bought the fuel here in da south and it got COLD on the way...

and one time when I tuned the truck and wanted some extra cetane boost when we went to hand a mouthy young hemi driver his butt at the dragstrip

 

It appears that you don't drive much so I would focus my attention to fuel additives that ensure quality fuel that sits a long time. If I were you I would just use the Ford Motorcraft fuel treatment.

Tire wheel combos vary as much as the folks who own these trucks. If you want 18" wheels your tire options open up a lot. What's your rear differential gear? If it's a 3.55 you will end up with a speedo/odo reading off by at least 5mph. My speedo is off by 5 mph with stock tire size when the tires are worn out, just the tread wearing down is all it takes to mess with the system.

 

For what it's worth:Source: The owners manual.
The owners manual can be downloaded from syncmyride.com in a PDF format.
When browsing that document, hit Ctrl F to bring up the search box and type in "fuel additive" without the quote marks.

 

That is kind of funny when they sell an additive for us to use in our trucks....

 

That's really funny, I've never seen that. Actually, my service manager always encouraged me to use cetane booster and winter additive.

Anyways, I ran the Motorcraft for the first 6 months I had the truck but switched to Diesel Kleen because of its price and availability. I'm really adamant about using it every time I fuel up and haven't had any trouble.

x2 on getting Nittos

 

I think that's "lawyer speak". It stands out pretty clear.
CYA

 

Then you have a document like this from Ford that discusses Motorcraft PM-22-A. Lots of writers, different departments (I'm sure).

 

18" or 20" won't make much difference, The difference is the Overall Tire Diameter. A 34.1" diameter tire regardless of the rim size still turns the same number of revolutions per mile.

The 35" tires fit OK but it really depends on your tire width and the wheel offset.

Understand that most floatation tires ( 35x12.5 ) run at lower PSI usually 65 psi vs the metric tires ( LT275x65r20) run at 80 psi. So you give up load carrying capacity. Most of the 35x12.5 tires are rated at 3195 lbs where as the LT 275x65r20 are 3750lbs. So each tire gives up 555 lbs or 1110 lbs per axle or 2220 lbs of payload per truck. You basically turn a F350 into a F250 as far as load carrying capacity.

These new engines have such precise tolerances, That there is not much of a break in period. I just have not seen an increase in fuel mpg as the mile accumulated. So I wouldn't hold off for long periods on using what every additive you choose. But do your research and decide if you feel you need better Cetane, better lubricity, anti-gel or biocide and buy the additive that serves that need.

 

for those that haven't done it ---
get your vin and go to Official Ford Owner Site | Schedule Vehicle Maintenance, Get Tips, Advice & Coupons
to register and download all your manuals and review all the recalls, maintenance, etc.. for your truck...