Bingo.

Oil analysis are good to ensure that your oil is holding up within the manufacturer's recommended change intervals, and to look for potential problems (if you know how to interpret the data).

However, an oil analysis isn't a permission slip to extend oil changes. There are many factors that go into healthy oil, and while an oil analysis will tell you the oil will hold up under some generic uses, it doesn't mean that it's still fit to continue for another "X" extended miles and still perform at spec elsewhere, such as the high pressure oil system specific to the 7.3L.

 

The same HEUI system is used on the T444e and that engine recommends a 10k oil change interval. Granted, that engine also holds about 2 quarts more oil but there is no reason that any 7.3 running a larger filter and/or bypass should not get at least 10k between changes if not more. I would argue that for many, oil changes come down to "I have always changed at X number of miles so I will continue to do so" type of a situation. This is one of those discussions that will never end as everyone has their own opinion on oil changes. Almost 15 years now on this truck with "extended" oil changes and I have yet to even open a valve cover. Does this have anything to do with oil changes, probably not but the forum is full of people that stick with 5k or less changes that seem to always be inside their engine fixing things.....

 

I am not disagreeing with you at all...it is very subjective.

and then you add tuning, larger injectors, larger turbos, and the list goes on....all of which create more stress and heat.

So, I am not sure that the 10k OCI is relevant unless you are "factory" stock....

I have gone as much as 11k on one OCI, with BPF, with testing that said all was well...the injectors sounded like there were gnomes with 5lb hammers under the VC's...never again.

So, short of being stock or mostly stock, 5k is very prudent and safe/great advice for all...especially on a forum where someone may read an opinion by an "outlier" and "assume" that it is gospel just because it fits his/hers wishes through cherry-picking.

Then again, you can't protect everyone...

 

Agree, the more you get away from stock, the more issues you will have. Not just in oil but in everything. With a good quality synthetic in your average truck, or slightly tuned, you should be fine. I would argue that those who take the time to go with tuning, larger injectors, larger turbos...etc., are not usually the type that are going to ask in open forums when they should change their oil.

 

Really? Can you explain that? I was under the impression that that is exactly what synthetic allows. That synthetic oil doesnt necessarily provide better protection, but that it provides adequate protection longer.

You must be saying that there is no benefit to synthetic oil OR that it provides better protection for a normal OCI, but then drops off dramatically and suddenly.

 

Without disagreeing here, the T444E is a different beast. Yes... it has the same block - but after that an International mechanic gets completely lost on a Powerstroke. I have to ask if it typically sees the same ICP, RPMs, and torque output as its Powerstroke brethren.

 

So Im confused. Are we now saying that, all things being equal, that if you switch from conventional oil to synthetic, that you can not run that oil any longer than the conventional?

 

Well I did a little research and learned a thing or two and I think I see what the deal is. Forgive me for thinking out loud, but Im just looking for info, please correct me where Im wrong. Synthetic oil does last longer, but it will still get dirty at the same rate. The dirt and contaminants is what will wear out the injectors.

(On a side note, both the 7.3L and the 6.0L used the HEUI system, however, the 6.0 creates higher pressure and the valve inside the injectors is also different between the two, in that the clearances in the 6.0 are tighter than those in the 7.3. This difference makes the 7.3 injector a little less vulnerable to dirt and contaminants in the oil, and thus, more reliable. That being the case, I think one could say that, all else being equal, clean oil is more important in the 6.0, at least in regards to injector life.)

So I guess the question is, how dirty can oil be before it starts to accelerate wear on the injectors? Is it possible that it takes 7000 miles of oil use before the oil is dirty enough to cause undue wear on injectors, but that, with conventional oil, its wear protection on cylinders, etc, went away at 5k so thats why it should be changed then? And if synthetic can go 7k before its wear protection wears out, then there would be no need to change it before then I guess?

And I guess used oil analysis can tell you about any wear metals present, TBN of the oil, and its useful life, but can't tell you if the amount of contaminants in the oil is doing harm to your injectors, correct?

Do we know what Ford was basing their recommended oil change interval on? Were they basing it on the wear protection of the recommended oil or how well the factory filtration system filters the dirt?

Maybe the answer to the OPs question is, if you ran your conventional to 5k, you can run synthetic to 7k, as long as switch to a better filter that filters better and can hold more contaminants?

 

It's not as easy as that. The HEUI system creates a lot of shearing of the molecules. A 40 weight oil will become a 30 weight oil after some shearing is applied for a length of time, then if left in the system for too long it will become a 20 weight oil. Viscosity is very important at operating temperatures and pressures.

 

So you are saying that synthetic does not withstand shearing any better than conventional does?

 

That IS what I was told by someone (actually more than 1) who was a Schaeffers rep when I first switched to their full synthetic. They said that their blend (7000) would work better for extended oil change intervals than their full synthetic (9000). The shearing forces in the HPOP and injectors was high and would degrade the weight of the oil.

Here is a good link for you to read.
https://www.ford-trucks.com/forums/1...or-a-7-3l.html

 

So they were talking about their brand and blends/formulations.

Does that apply to the other brands? Based upon what I have read from UOA's from BobIOG and other forums, the answer is quite possibly "No".

With most other brands that start with a 15w-40 or a 5w-40, the shearing actually begins to stabilize at around the 35 down to 30 mark. I have not seen or maybe I don't remember any brand that sheared down toward the 20 range. Does Schaeffers continue to shear to that point?

I am not trying to talk bad about their products, I actually really like Schaeffers transmission fluid better than anything else I have tried. It is all that BTS uses.

 

Correct me if Im wrong, but aren't both the 7000 and the 9000 "synthetics"? The 9000 being a full synthetic, and the 7000 being a synthetic blend, much like the T6. Regardless, according to the Tech Data Sheet of the 7000 15w-40, the viscosity percentage loss due to shear is 9.96%. That same figure as it relates to the 9000 5w-40 is listed at 10%. I would think that a difference that small would have just as much to do with the difference in the range in viscosity index between the two oils, if not more, than the difference in synth versus synth blend.

 

In answer to your question regarding Scaeffers vs. other oils, I can't say they were necessarily speaking about any other manufacturers oils, but I am of the OPINION that theirs is as good if not better than any other synthetic out there, so if it applies to theirs, in my mind, it applies to every other synthetic. In other words, if theirs doesn't stand up, I don't believe any other brand will either. But that is an assumption on my part. As for their 204S tranny fluid, I just ordered 5 gallons of it for whichever new transmission I buy next week.

I think that the HEUI system makes a big difference for the talk of extended oil change intervals. I don't think that when we talk about oil change intervals on other systems, it applies to our trucks. On a basic push rod gasoline motor, or a common rail diesel engine, you aren't putting the kind of stress on the molecules that the HPOP does. So you certainly can extend them, but I would do some used oil analysis. In my case, my used oil analysis showed better results using standard 15W40 oil when I extended it out to 9K miles. When I tried it with Schaeffers, I had to change it closer to 7,000 miles. Then my injectors were shot at 155,000 miles soooo.... I am not saying extending my oil changes was totally the cause, but it sure must not have helped. I am not running supplemental filtration and as they say YRMV.

 

No you are correct. They told me that the 7000 blend would stand up better to shear and extended oil change intervals than their full synthetic 9000 would.