I keep reading that short trips are bad for diesels. While I understand the reasons for this, I'm not sure what "short" means. If the coolant gauge shows that the engine has completely warmed up, is that enough? In this warm weather, I can drive 3 or 4 miles up the road and have the engine fully warmed up according to the coolant gauge. Is that enough to prevent problems?

 

When my coolant gauge reaches the normal position right in the middle my scangauge is reading 130. Then the scangauge continues on up to the 190's while the dash needle is fat, dumb, and happy right in the middle.

My Trans temp does the same thing.

Either way it's not like you're going to circle the block for 30 minutes to change anything about it.

To answer your question, my opinion is a "short trip" is where the temp doesn't reach normal operating levels (coolant in the 190's), which cannot be determined accurately by the factory dash gauges.

 

Just searched 4,963 pages of the Ford Factory Workshop Manual (using the search button of course).

No where does it state a specific temperature.

It does however read "Warm engine to Operating Temperature to perform test" 231 times.

And, "ensure engine temperature is above 140*F prior to testing" 19 times.

And, Run Engine at 3,400 RPM for four minutes to ensure the engine is at operating temperature when testing for air @ the ICP 5 times.

I know from training the Oil Must reach a certain temperature to off gas moisture, acid, and other contaminates.

 

One thing to keep in mind... just getting to the normal operating temperature (NOT) is only the first step. Since it is at that temperature when the moisture, fuel, etc. is expelled, there has to be adequate time AT the temperature for these contaminants to vaporize and get discharged from the combustion cycle. It doesn't all happen in a "flash" just as the NOT is reached... the engine has to run there for some time, and just how much time is dependent upon how much contamination exists (the more the engine wears, the longer this "burn off" time will take).

Personally, I have been making 9 mile runs to my office every other day which is enough time for me to reach NOT and remain there for about half my 18 minute trip. Is that enough time? I'm honestly not sure, because I also typically have 2x85 mile one-way trips every other day which are more than adequate to burn off anything not taken care of in my shorter trips to the office on in-between days.

This is an issue of interest to me though because my 8-year long habit of driving as described above is getting ready to change significantly. So now, where I started the above driving pattern with an engine which had less than 120K miles on it 9 years ago, I am now going to face only a 4 mile trip to my new office where the in-between long day trips will be virtually eliminated altogether, and this on an engine which now has nearly 280K miles on it. Consequently, I'm already assuming that I'll need to make at least one weekly trip through and around town with at least thirty minutes of continuous driving to ensure I don't begin to get a buildup of fuel or water contamination in my oil sump.

 

I have driven a daily 7 mile trip to my job since 2001.

 

Some good points are made.

I would think that the most important thing is to keep the Fluids Changed as prescribed in the Owner's Manual.

Are short trips Normal or Severe Service Schedules?

I know with short runs the Exhaust Parts tend to deteriorate faster; as moisture is a product of combustion and heat is required to vaporize it and move it out. But, I suppose that is more on the Gasser side as compression and cylinder combustion temperature is much less.

Some very interesting reading here: Used Oil Analysis - Bob is the Oil Guy - Bob is the Oil Guy and: http://www.bobistheoilguy.com/motor-oil-101/

 

Also consider a truck that only sees short trips and one that sees short trips all week for example and long trips on the weekends. I think that regular longer trips balanced with the short ones will minimize moisture buildup.


I think about this when it comes to idling as well. I have heard many times it is bad to idle these engines for extended periods at normal idle speeds. My truck sees mostly highway miles right now, and I am in the habit of letting it idle while fueling, while eating, while registering for a hotel room, pit stops etc. I just do not like to shut down a hot engine. Occasionally there is up to a 2 hour wait at the International border crossing and I'll idle the whole time with the AC cranking. On a 8-10 hour trip I will rarely shut down. (If I can't see it I put the Club on the steering wheel and lock the doors) I don't think this is detrimental because it is balanced with hours of high speed driving in between, which would clear out any wet stacking. Plus, I like to let everything cool down good after a hard run before shutting down.

 

High idle options on modern chips and programmers are there for a good reason... keeping the engine fluids hot enough and flowing fast enough to maintain the vaporization of any fuel and/or condensation which might otherwise get ingested into the oil sump.

It is this exact issue which led to some early failures on the 6.4L engines... drivers who idled a lot actually measured increases in their oil sump levels due to fuel dilution getting past the rings during a low-engine-load regen cycles. Consequently, the fuel dilution reduced the engine oil lubricity and there were documented engine failures as a direct result.

Granted, we do not have the heavy fuel dump regens taking place in our 7.3's, but the anecdotal evidence remains valid and is worth keeping in mind.

 

Our local power company employees let their service trucks idle all day, no high idle controller. They have lost more than a few 6.4s with less than 75K on them. Can't tell them any different. Their solution? They are buying Dodges.

 

Way too often, once people become managers, they stop thinking and forget all about that little thing called "root cause", and become they then become experts at buying band-aids while shouting out to all their bosses.... "See how well I managed THAT one?!"

 

Just as an observation, I also have a C6 Vette and I can tell you watching the oil temp on the DIC, that it takes the oil much, much longer to get up to temp +- 200 than the coolant temp.. A LOT longer... and I would think with almost 4 gallons of oil in these trucks, it would take even longer to get up to moisture boil off point..212..

 

Bingo.


It takes a lot to heat up that much oil.

 

I would think that a 2 hour trip (driving 1 hour each way, with generally 1 hour layover) would be enough to heat things up enough