Fuel in Oil

[roberthall0]

I have had my 2010 for almost exactly a year. The truck has been making oil since it was new. Until recently, the oil would never get more that about a half inch above the full mark on the dip stick. I had the oil analyzed about six months ago and the analysis showed about three percent fuel dilution. Recently when I checked the oil it was higher on the dip stick than it has ever been. This time the oil was about an inch over the full mark. I took another sample of the oil and sent it in for analysis and found out now there is 7. 4 percent fuel dilution. The truck is not showing any codes so the dealer told me there was nothing they could do. The truck is used to pull a 15K 5th-wheel camper once in awhile and to pull my tractor on a 24 foot trailer occasionally (about 10K pounds). The rest of the time I use it as my daily driver (about 50/50 highway and town driving). The truck has about 17,000 miles on it. It is my understanding that it is fairly common for the 6. 7 engine to get a small amount of fuel (1 to 2% dilution) in the oil. However, 7. 4% dilution (about a quart of diesel fuel) can not be good for the engine. I don't let the truck idle except at stop lights, etc.



How do I find out what is causing this problem? My guess is it is the injectors but I guess it could also be the rings have not seated yet. What I don't understand is why it is getting worse unless it is a faulty injector that is getting worse. I realize it is not unusual for 4th gen trucks to get some fuel in the oil during regen but I would not think that 7% dilution is acceptable. Unfortunately, there are no good diesel mechanics at the dealerships in this area, at least none that I am aware of.



I sure would appreciate some guidance from you guys that have had some experience with this problem.

 

[Bob4x4]

Yuo haven't mentioned your oil change interval-that is very important on the 6. 7.

 

[roberthall0]

Thanks Bob, I should have thought of that. I have been changing the oil each time I get a oil change message from the truck's computer. The first three messages came on at 4,200 mile intervals. The 4th message came on at 3,700 miles. The oil samples I had analyzed were taken during the 2nd and 4th oil change.

 

[sag2]

I have done dozens of samples on 6. 7's and the oil change light usually comes on in the 5% range, but I have seen as low as 3 and as high as 8%. Your truck is doing exactly what it is designed to do. The amount of dilution has most to do with the driving conditions YOU experience. Light duty=high fuel dilution, heavy duty and towing=low fuel dilution. Drive it and enjoy it, just change the oil within 500-800 mi of when the light comes on.

 

[roberthall0]

Thanks Sag2. I have read several of your posts in the past and it is obvious that you are very knowledgeable about these engines. Your comments make me feel better but I have this nagging feeling that a quart of diesel fuel in the crankcase cannot be a good thing. Guess I'll just have to learn to live with it. Your comments are much appreciated.

 

[GaryCarter]

If I may tag team on this thread- my truck gains oil at the rate of about 1/2" or so in 3 thousand miles of towing. From what I've been reading, the fuel dilution around town is a fact of life. Seeing it happen driving interstate speeds with the trailer on surprised me.



I changed oil at 2k and 6k and truck has 9k now. The change indicator went off the first time around 6500. I'm going to pull a sample and change it soon.



If this was a 5. 9 I'd be taking it in to the dealer, but from what I've been reading this is nothing unusual with the 6. 7's. If anyone thinks this is a problem, please speak up. I'm expecting some warranty related parts to fall off my truck soon.

 

[roberthall0]

Gary, your experience has been very similar to mine which leads me to think it is probably fairly normal. However, if it is normal it surprises me that more people are not talking about it on these these forums. Before buying my truck, most of the comments I read indicated that most of the bugs had been worked out of the 6. 7. If the only way to solve this issue is to do the deletes then it is my opinion the technology is not where it needs to be yet. I agree with you, it would be nice to hear from others about their experiences and what percentage dilution they consider to be abnormal for the 4th gen 6. 7.

 

[JHumphries]

This is an older thread
https://www.turbodieselregister.com...ive-idle-time-po-ed-customer.html#post1966814
But, the end result is similar. The "How high is the oil mama" answer don't worry about it.
I thought I remembered something about some CP3 leaks into the crankcase, but I can't find it.

 

[roberthall0]

Thanks JHumphries, that was a helpful link. Based on comments made in the referenced thread we could have excessive idle time even if our trucks are not allowed to sit idling. The thread does not make it clear how idling is calculated but it sounds like any time the engine is running and accelerator is not being depressed (for example coasting down a hill) it is classified as idle time. Consequently, idle time has a fairly large uncontrollable element.

 

[RustyJC]

Before buying my truck, most of the comments I read indicated that most of the bugs had been worked out of the 6. 7.

I suppose the point is debatable, but I don't consider more frequent oil and filter changes than I was used to with my 2002 a "bug" in the sense that something is likely to fail and leave me standing beside the road.



Could the situation be improved? Certainly, if Cummins had added a 7th post-injector a la Duramax and brought the additional fuel required for regeneration outside the cylinders so that it couldn't get into the crankcase oil. As of this 5 minutes, though, it's the nature of the beast in its current configuration.



Rusty

 

[Newt]

As long as we are talking about oil.

I recently was able to do "my" first oil change ~30,000 miles. The others were done by various shops. The oil was always ~2 qts high after the oil change. I thought they were not letting it drain long enough. I let it drain for 1 hour. It still showed ~2 qts over.

I'm just a little ******. Is the dip stick faulty or what?

Newt

 

[roberthall0]

Newt, I always change my own oil and the oil level is always on the full mark when I refill the crankcase with 12 quarts of oil. However, the oil level starts to grow after I start putting miles on the new oil. I always get the engine up to operating temperature before changing the oil to make sure all of the oil will drain from the engine. I remove the oil fill cap before draining the oil to make the oil drain better and I let it drain until the oil quits coming out of the oil pan. I then replace the oil filter and then fill the crankcase with 12 quarts of oil. Then start the engine so that oil will refill the oil filter. Then shut off the engine and let it sit for about 15 minutes to let the oil drain back into the the oil pan and then check the oil level on the dipstick. To get an accurate oil reading your truck must be sitting on a level surface. Following this procedure, my oil is right on the full mark after an oil change.

I may start adding only 11 quarts of oil when I do an oil change so that when the oil starts to grow due to fuel dilution it will not go so far over the full mark. I have always believed that it is better for oil to be a little low than to be over full mark.

 

[JHumphries]

... I may start adding only 11 quarts of oil when I do an oil change so that when the oil starts to grow due to fuel dilution it will not go so far over the full mark. I have always believed that it is better for oil to be a little low than to be over full mark.

In other vehicles that may not be horrible, but in this engine, less oil to start with means the fuel percentage goes up faster. Therefore you approach the lack of lubrication faster.
If the level being high is a concern, put one of the valve style drain plugs on the sump and drain out a half a quart or so when you notice the level high.

 

[roberthall0]

Rusty, I fully agree with your comments but I was really surprised when I found out that that I had 7. 4% fuel dilution at my last oil change. The first time I had the oil analyzed I had 3% fuel dilution. I was not happy there was 3% dilution but thought it was probably normal and nothing to worry about. But with 7. 4% dilution I became more concerned and wanted to find out what others were experiencing. According to Sag2, 7. 4% falls into the "normal" catagory. I have read several of Sag2's earlier posts on this forum and he seems to be a knowledgeable technician and I believe he is probably giving me good advice. However, even if the fuel dilution does not harm the engine, having to do 5 or more oil change a year is not very desirable.

 

[RustyJC]

I guess our duty profiles for the truck differ. We use the truck almost exclusively for towing our 5th wheel (see signature), and we're not full-timers yet. Therefore, we can get 4-5 long weekend-type trips or a major vacation trip on the truck before an oil and filter change is required. I knew that was going to be the case when I bought it, so I just change the oil about every 3K to 3. 5K and go on with life.



By the way, I've never waited for the oil change notice in the EVIC since, Murphy's Law being what it is, invariably it would come on 5 miles after we started a trip. :{



Rusty

 

[roberthall0]

JHumphries your advice is well taken. I bought a EZ Change Drain Plug from Geno's and installed it the last oil change.

 

[roberthall0]

Rusty, I also own a Mobile Suite but it sounds like you tow more than I do. During the past year we have not been able to use our camper much. Hope to be able to use it more in the future. Thanks for your comments.

 

[Newt]

After letting it drain for an hour, I expected the oil level to be correct, not 2 qts high. Kind of ****** me off.



Newt

Newt, I always change my own oil and the oil level is always on the full mark when I refill the crankcase with 12 quarts of oil. However, the oil level starts to grow after I start putting miles on the new oil. I always get the engine up to operating temperature before changing the oil to make sure all of the oil will drain from the engine. I remove the oil fill cap before draining the oil to make the oil drain better and I let it drain until the oil quits coming out of the oil pan. I then replace the oil filter and then fill the crankcase with 12 quarts of oil. Then start the engine so that oil will refill the oil filter. Then shut off the engine and let it sit for about 15 minutes to let the oil drain back into the the oil pan and then check the oil level on the dipstick. To get an accurate oil reading your truck must be sitting on a level surface. Following this procedure, my oil is right on the full mark after an oil change.



I may start adding only 11 quarts of oil when I do an oil change so that when the oil starts to grow due to fuel dilution it will not go so far over the full mark. I have always believed that it is better for oil to be a little low than to be over full mark.

 

[roberthall0]

Newt, how many quarts of oil did you put in after draining the oil and did you change the filter?

 

[Newt]

Newt, how many quarts of oil did you put in after draining the oil and did you change the filter?

3 Gallons of Rotella. Of course I changed the filter.



Newt