Sounds like you're doing something right. Do you run oil or fuel additives?

 

FWIW, I started using Mobil TDT when my truck hit 10k miles. Got 210k on her now. Had some top end work performed at 75k, 180K, and again at 210K. Each time the mechanic just raved at how clean the internals were. Made me feel real good about my choice.

 

I have added Archoil 4 or 5 times just to get data on the oil analysis. Never have had any stiction to worry about (knock on wood).

I try to use a fuel additive most of the time. Don't always do it. I had a few years where I didn't feel like I could afford to do it, but resumed doing it a few years back.

 

I thought that too but it wasn't obvious according to their info. And they have a separate price schedule for soot.

Any diesel engine oil analysis where you're considering extended drain interval should always include soot

I wouldn't worry about 7500 miles either.....Even 10,000 miles. The VT-365 recommended oil change is 10,000 miles.....
[same engine in a medium duty application]

www.astleford.com/pdf/vt365brochure.pdf

Even Cat recommends 250 hrs for the 3126 (also an HEUI engine)

250 hrs @ 60 miles per hour would be equivalent to 15,000 miles.

methinks we might be worrying much about oil..........

 

for me thats the whole point of the testing. To help us stop over worrying.

So far in life I change the oil pretty much when they say, with some exceptions where I do it much earlier. But I don't worry over it too much. I was curious about the testing procedure and also my mystery motor as it was just found on a shelf without any idea what it had been through to get there.

Now, I've seen some people state that if we are going to be swapping oil at 5k miles, then we might as well use conventional oil because the synthetic won't be really that helpful. This is possibly true and we should be able to verify it with testing. Has anyone done that?

 

First off - I appreciate the post and perspective. I certainly think you have some valid points!

That said, stiction issues are real with these injectors. It isn't just the fact that it is an HEUI engine. The 7.3L is an HEUI, but the design of the 7.3L injectors is so much more robust. 6.0L injectors are expensive and if more frequent oil changes provides less chance for experiencing this injector issue, then by all means it is worth it (from a financial perspective). I am not sure that there is a relationship between stiction and OCI (assuming good filtration), but it seems to me there has to be SOME upper limit.

Also, the VT365 isn't rated for the same horsepower as the 6.0L (at least that is what I recall and could not prove otherwise from the link you provided). This means more heat and more wear (more fuel consumed per mile and per hour). Not exactly sure it is an apples-to-apples comparison. Ford's max OCI is 7500 miles and that is what I based my upper limit on. Additionally, if you saw my iron numbers, you would understand my interest in oil and oil change intervals. Granted, my elevated iron seems more related to the choice of oil, but clearly the interval impacts it (I have pulled samples in between oil changes to "somewhat" evaluate the rate of increase. Seems that much of what I see is unique to my particular engine, but I will say, not a ton of people spend the money on oil analysis! The issue with making decisions on oil is that it takes years to compile data that has any practical meaning and (since engines do not all behave the same), it also takes a data set of that is fairly extensive (large test population).

As far as viscosity goes, there are a number of smart folks that advocate 10W30 oil and have exceptional UOA to back it up. For them, 30 wt oil viscosities have been no issue - no doubt it works (including towing and hot weather operation). That said, there clearly is a limit to OCI's, because even the 10W30 oils shear, and some 5W40 oils shear A LOT faster than others. I have seen some UOA (both 10W30 and 5W40) with viscosities near or at the upper 20 wt spec. So ... what is the limit and the potential consequence?? Not sure I want to be the guinea pig. For example - I still haven't seen a concrete explanation for the reason for lifter failure.

When I make decisions w/ this truck, I am doing so on the basis of obtaining a 350k mile life with minimizing the "catastrophic" repair costs. I am almost at 200k miles and doing well. I look on the FTF board and see Beachbumcook at 300k miles (with minimal repairs) and think that he must be doing something right! Anthony certainly achieved some incredible miles before his catastrophic failure, but I am not sure I have seen him weigh in on any oil and oil change discussion.

Anyway - just my thinking out loud, most of it based loosely (at best) on science.

Edit -

On another note, I can't thank you enough for the link! I have been in some pretty heated discussions (multiple forums) regarding the oil capacity of our engines. I have held to that total capacity being around 18 qts for a LONG TIME (based on input from well respected folks). Some forum folks chose to adamantly disagree with that and insist it was 14 plus the 1 to 1.5 extra for the HPO system as mentioned in the 6.0L bible document. I could never find Ford documentation to back up the "ca" 18 qts. The VT365 brochure lists this capacity at 19 qts!! Again - many thanks!

 

I've only had 2 oil analysis done. First OA was at 153K miles. Second at 163K miles. My first OA was using T-6 and with 5,350 miles. TBN = 8. SUS @ 67.
Second OA on Delo 5-40 with 5,500 miles. TBN = 7.9 SUS @ 62.9.
All other numbers were in good/acceptable range. They did comment on the low SUS on Delo, but still recommended increasing OCI to 7500 miles. I have not extended my OCI's but was wondering if others have received and followed the same recommendation.
I'll do another OA at around 173K miles.

 

I agree with everything you're proposing here, and I do want to avoid lifter failure and injector problems for sure. The vt365 engine is in fact rated at lower hp. I'm not exactly sure but I believe that they say right on them 375hp, and our engines are labeled 425? Something like that. However, this doesn't mean they are using more fuel and being run harder. They used vt365 in busses and equipment where they were taxed much more than my particular truck is on any given day at 8500 lbs wet. Sure, sometimes we hitch up the boat but for the most part my engine has a much easier life than most any vt365 engine.

 

I'm on my second fill of Schaeffers 9000 5w-40 with Archoil. I'm going to send in an oil sample at 7500 and see what they say. I'm also running a bypass filter setup with an Amsoil EaBp100 filter and this will be my first run with it on there for the entire drain interval. I'm not looking to extend beyond 7500 but just keep my injectors and lifters happy. If they recommend going to 10,000 I may do it but my thinking now is to stay at 7,500.

 

I had a really long post to this tread a few days back, went to another tab and when coming back lost it all.

Posted before, maybe once more, the old oil analysis spreadsheet of participants from DTS long ago.

The 6.0 is a curious animal compared to the 7.3 where we had seen guys go 50k miles and longer with extended changes. There was a member early on who I thought was a Nav engineer who posted about the shearing issue, and my take has always been the 6.0 shears down the viscosity modifier and the oil ends up at the base level. From the initial fill data collected in this pdf's graphs, you can see it happening pretty good at 3k mile life.

Extended life per Blackstone seems to be more in line with how much contamination is in the oil, including wear metals. If I posted the 7.3 data you could see that.

To me this motor has a very wide oil pressure delta by temp. While it's stated there is a 75 psi high pressure regulator off the base oil system, those who have installed agauge (not me) have noted on cold start all the way to 100psi at idle. Then it can be reported at hot idle the pressure is down typically in the 20psi range, and not unheard of around 15psi.

So for me it's the hot idle where I think things get problematic, mostly for lifters in a 6.0 and 6.4 since these are the motors that these widely used lifters in many motors get their roller bearings to fail. These are the only motors where the lifter have to open twin valves.

It's pretty well understood that the VT365 does have the head gasket issues the 6.0 has. With it's lower HP the injection event is a longer process for torque rather then higher volume early on for more HP, at least the way I understand it. That may have a lot to do with bearing wear and oil film compression in the lower end, but it changes nothing at the lifters. But it's possible if the 6.0 is programmed for higher HPOP system pressure for operation, the higher pressure generated and the resulting flow through the injector per a given motor state is why the oil viscosity is not lasting in the 6.0, and the need for early 6.0 intervals. Just SWAGing here.

In one of Anthony's video's he is trashing a factory rebuilt motor as it's worn out everywhere. But as he was going through it's problems from my gas motor life I kept thinking low oil pressure .... low oil pressure, not who rebuilt the motor. Maybe I'm mistaken but I thought the background vehicle the motor came from was a service truck with a bucket lift. If that ain't long idle I don't know what is. And long idle trucks like that often don't get oil changes as often as their mileage indicates unless the maintenance is based off engine hours rather then mileage.

Most lifter failures in the 6.0 seem to be the back cylinder 8 lifters highest, 6 the next. Cylinder 7 lifters are much rarer and the more forward lifters rarer still, not that they don't happen. The cylinder banks oil passage ways feed the lifters, but it's the odd bank passage that also lubricates the cam bearings and finally the main bearings. At first the gut feel is this might result in low pressure compared to the drivers side, but that would be dependent on the feed passageways coming from the top of the motor. That's not what I'm thinking may be happening.

With the drivers back passage only flowing to the lifters, the oil has a longer dwell time in that passageway since the volume is so low. In my mind its possible the oil in that passageway reaches a much higher temperature, absorbing more heat energy from the nearby piston cylinders duet the swell time.

Mark K could probably tell this story better, but how much thermal energy is absorbed in a cooling media is dependent on flow rate, and sometime it's best to slow down flow to get the best absorption as I understand it. So the oil waiting to feed the lifters on the even drivers side gets hotter, and lower in viscosity. And maybe that's the reason for the roller failure rate to be higher on that bank, especially if the truck is at idle generating lower oil pressure.

Sorry, just SWAGing in writing.









Attached the spreadsheet for Gabriel.

 

I have taken a lot of heat transfer classes and you don't often times get better heat transfer by slowing down the fluid flow (only if you are desiring different flow characteristics like laminar instead of turbulent flow in some fairly high fluid velocities). If you have heat that you want the oil to reject, assuming a constant heat transfer area, you increase the flow. After a point the turbulence will drop the heat transfer efficiency, but these flows are not designed in that region because of the lower oil pressures that you pointed out.

I agree that oil temperature is a key to the performance and longevity of these engines. Oil temperature will drop the viscosity and will lower film coefficients. If viscosities are too low (whatever that lower tolerance might be), excessive heat will only make it worse.

 

interesting guys. i wonder if a correlation between lifter failure and oil cooler problems could be drawn. If the oil is allowed to reach up to 250° or even higher, maybe that hi range is critical to the viscosity, where it loses film strength and pressure simultaneously. In this case does a 15w40 grade make more sense than 5w40? I know they say that the 40wt part of the rating is all that matters at operating temp but I'm not sure I totally believe that.
Also, is there any emerging data on oil additives vs lifter failure? That would be something to note as well.
So, in the data about shearing down considerably at 3000 mi, does that suggest that conventional or syn blend oils would be just as good in the engine with a shorter oci?

 

Mark, you've got way more then me in that area and I probably should have written that better. What I trying to get across was the dwell time of the oil volume on that side, staying and heating up. I should not have brought up the flow rate issue which gets into the turbulence, laminar issues, on and on. I was just trying to say it may stay there for too long, heat up too much compared to the other side.

Gabriel, with that data base was we only had multiple points of consistent information as some people changed the factory oil at 1k, or 2k, or ....... out to 7k miles. So those were only direct correlation where you could reliably plot out the viscosity change. Afterwards it was mixed oil sources and intervals.

 

Absolutely agree! I wasn't suggesting we try 15,000 of course...... (I don't even exceed 5000 myself!!)

Here I would wonder if maybe the FOMOCO flavored VT-365 has a smaller pan! Would that huge pan even fit in the F250/550 series pickup frames?


If the 5W-40 oil is a true synthetic, it will "Stay in grade" I.E. SAE40 at the higher temps as well as any 15W40 or straight wt 40 will.

If the 15W-40 is a NON-synthetic, it's actually a 15W oil that uses Viscosity Improvers to make it a 40 @ 100C (BUt it's STILL a 15w oil and as those Vi Improvers degrade, the oil will begin to thin. (hopefully you change it long before that happens)


SO, the answer is the 5W-40 (syn) is always better at higher temps than any non-syn multi-grade.

 

Your running 25% more oil capacity Why not run it 1/4 longer (7.5k) on the the mileage before changing oil? Should roughly be in the same condition a normal sump would be at 5k miles.