What is the quarts "range" on the dipstick on these trucks?

[Fairweatherider]

So after reading all 6 pages I have a question regarding oil dilution. Is extended idle time only an issue at cold start up? Meaning, after reaching full operating temperature, can I idle the engine for an extended time without causing oil dilution? I’m in Texas and it gets so hot in the summer that we regularly idle for extended periods of time just to keep the air conditioner running.

I also have one other question, this one regarding oil viscosity. Is there really a “one size fits all” oil viscosity? How can 0w-20 work properly at temperatures far below zero in Russia and 110 degrees Fahrenheit in Texas? I suppose the real answer lies in the oil temperature and not the ambient temperature. I am tempted to prescribe to the old method of using a thicker viscosity in the summer but at the same time, I’m hesitant to go against the manufacturer’s guidelines.

 

[jfoj]

The best way to think about fuel dilution is the following, these are pretty good generaliztions.

1. Atomized or liquid fuel does not burn, vaporized fuel does burn.

2. On a Direct Injection engine, the fuel pressure for the fuel being sprayed into the combustion chamber can be in the upper range of 2500 PSI.

3. Cold starts require a richer fuel mixture.

4. Engine idle requires a richer fuel mixture than cruising.

5. A cold engine take longer for the coolant and oil to warm up while just idling vs. starting the engine, allowing the RPM to drop (15-30 seconds) then driving normally. The faster the engine coolant and oil warms up, the less fuel gets into the oil and the better chance some of the fuel in the oil can be "cooked" off.

5. Cold starts and cold idle are more of a problem for fuel dilution due to the engine components not being up to full temperature and expanded to seal up the combustion chamber. Piston ring end gaps are larger, piston skirts are not fully expanded and the piston may not be warm enough along with the cylinder walls to help vaporize the fuel. Cold pistons and cylinder walls will cause the atomized fuel to condense and then typicaly leak past the piston rings. See YouTube video link below about the piston top shape and see how any liquid fuel can easily works its way to the lower portion of the piston. This video is of a L86 not a L87 engine, but they use the same pistons. No deep pocket in the middle of the piston like a Diesel engine for the fuel spray to be partially contained.

6. A fully warmed up engine will have less of a problem with fuel dilution because most thigs in #5 have been overcome.

7. Any extending idling is not good for any engine, sure police and fleet vehicles may have a great deal of idle time, but often police and fleet vehicles are maintained on a more frequent basis that a typical passenger vehicle.

8. Oil temperature is more a factor about the best oil viscosity to use rather than outside temperature or engine coolant temperature. Cleary any temperatures below say 20F starting will benefit from a lower viscosity oil for cold start performance. Oil Winter rating or the W rating is usually at 0F/-18C. But during an engines lifetime the high temp operation should really be considered. I was rather suprised to see my 6.2l oil temps at 226F on the highway the other day with no load in the vehicle and not towing anything. Above 212F/100C most VII (Viscosity Index Improvers) start to roll over the hill and the engine oil starts thinning out back toward the base oil level which is the number before the W in the oil viscosity value. I only takes 20F or more above the 212F rating limit for the oil thinning to possibly be a probem.

9 Extended idle, suggest you change the oil more frequently. Simplest indicator is just starting changing the oil when the OLM hits 50%. Better to be safe than sorry.


6.2l Tear Down, watch at 14:40 for piston view

 

[Vladimir2306]

The best way to think about fuel dilution is the following, these are pretty good generaliztions.

1. Atomized or liquid fuel does not burn, vaporized fuel does burn.

2. On a Direct Injection engine, the fuel pressure for the fuel being sprayed into the combustion chamber can be in the upper range of 2500 PSI.

3. Cold starts require a richer fuel mixture.

4. Engine idle requires a richer fuel mixture than cruising.

5. A cold engine take longer for the coolant and oil to warm up while just idling vs. starting the engine, allowing the RPM to drop (15-30 seconds) then driving normally. The faster the engine coolant and oil warms up, the less fuel gets into the oil and the better chance some of the fuel in the oil can be "cooked" off.

5. Cold starts and cold idle are more of a problem for fuel dilution due to the engine components not being up to full temperature and expanded to seal up the combustion chamber. Piston ring end gaps are larger, piston skirts are not fully expanded and the piston may not be warm enough along with the cylinder walls to help vaporize the fuel. Cold pistons and cylinder walls will cause the atomized fuel to condense and then typicaly leak past the piston rings. See YouTube video link below about the piston top shape and see how any liquid fuel can easily works its way to the lower portion of the piston. This video is of a L86 not a L87 engine, but they use the same pistons. No deep pocket in the middle of the piston like a Diesel engine for the fuel spray to be partially contained.

6. A fully warmed up engine will have less of a problem with fuel dilution because most thigs in #5 have been overcome.

7. Any extending idling is not good for any engine, sure police and fleet vehicles may have a great deal of idle time, but often police and fleet vehicles are maintained on a more frequent basis that a typical passenger vehicle.

8. Oil temperature is more a factor about the best oil viscosity to use rather than outside temperature or engine coolant temperature. Cleary any temperatures below say 20F starting will benefit from a lower viscosity oil for cold start performance. Oil Winter rating or the W rating is usually at 0F/-18C. But during an engines lifetime the high temp operation should really be considered. I was rather suprised to see my 6.2l oil temps at 226F on the highway the other day with no load in the vehicle and not towing anything. Above 212F/100C most VII (Viscosity Index Improvers) start to roll over the hill and the engine oil starts thinning out back toward the base oil level which is the number before the W in the oil viscosity value. I only takes 20F or more above the 212F rating limit for the oil thinning to possibly be a probem.

9 Extended idle, suggest you change the oil more frequently. Simplest indicator is just starting changing the oil when the OLM hits 50%. Better to be safe than sorry.


6.2l Tear Down, watch at 14:40 for piston view

We communicated with the service, they checked the oil when changing, there is almost no fuel in it, in a significant amount.
as soon as gasoline enters the oil, it evaporates intensively through the PCV system when heated, and this begins to interfere with the formation of mixture at idle. And if some kind of breakdown and fuel really gets into the oil in large quantities, this will immediately cause Check Engine, and errors 0172 and 0175

 

[jfoj]

We communicated with the service, they checked the oil when changing, there is almost no fuel in it, in a significant amount.
as soon as gasoline enters the oil, it evaporates intensively through the PCV system when heated, and this begins to interfere with the formation of mixture at idle. And if some kind of breakdown and fuel really gets into the oil in large quantities, this will immediately cause Check Engine, and errors 0172 and 0175

@Vladimir2306

The more I read about how you drive your vehicle, the more I realize you do not drive like the majority of the people here in the US. Part of this is probably due to the roads and the amount of traffic on your roads. Traffic volume and congestion play a big factor in how a vehicle can be driven at or above the posted speed limit. I have a bridge near my house that has an average of 235,000 vehicle that cross is daily! For almost 12 hours of the day that traffic is not even running near 1/2 the posted speed limit!



I really doubt you drive your Yukon as your "Daily" driver in the Winter months in Moscow taking 15-20 minute trips and rarely getting out on highway for extened periods of time. Additionally when you are driving your vehicle at over 100 MPH and 3000 RPM for long periods, almost anything will be "cooked" out of the oil. My truck has never seen more that maybe 1800 RPM on the highway for any extended period of time and I would bet this is the case for most owners here in the US.

Here in the US there is just no place you can easily, safetly and without dealing with law enforcement and heavy traffic run in excess of 100 MPH for hours. Too much traffic, too many trucks, too many idiots that camp out in the left lane and block traffic. Here in the US they do a poor job, if any, teaching people that the left lane is not for driving in full time and never moving out of. I drive a few routes for hours and there are always groups of 20-40 vehicles stacked up barely doing the speed limit because someone is always blocking the left lane. Rolling roadblocks is what these are called. This is TYPICAL here in the US.

I have lived in and driven in Europe for many years, and it is pretty clear you do not stay in the left lane, it is primarily for passing and in Germany you better not be in the left lane unless you are going triple digits on the speedometer and move to the right when you are not passing.

Again, I do not think you fully understand the driving, traffic and weather patterns here in the US. Because of many factors, the fuel contamination in the oil at times can become cumulative, meaning is builds up over time with shorter drives where the engine oil never gets up to even the engine coolant temperature. In many cases the engine oil in these trucks take 20-30 minutes to even reach 200F and even once the oil reaches 200F you need to keep it there for some period of time to "cook" as many of the contaminates out of the oil.

One member here that does not use his Surburan for work because it is only 9 minutes from his house and he does not want to kiil it. He has to accelerate up to close to 70 MPH almost immediately once he leaves his driveway. This can play hell on an engine with cold oil and the oil never would get much above the a 120F by the time the vehicle is shut down and this is not during Winter temps. Do this 5 days in a row and see what happens.

My wife travels 7.5 miles to and from work. The morning trip is maybe 15 minutes, but the evening return trip for the same 7.5 miles is typically 40-45 minutes. In either case, not ideal for engine oil in the long run. Luckily she does not drive a Yukon, but she still drove a vehicle with 7 quarts of oil and it would barely be warmed up on the way to work and the way home she crawled and barely was able to get car over 35 MPH. So this was clearly not an ideal situation for the engine oil.

You can have a high fuel percentange in the engine oil and still not trigger a CEL/SES/MIL codes for a rich fuel mixtures. The problem is once you are at above 2-3% fuel diluition in the engine oil, the lubricating properties of the engine oil is really starting to diminish and depending on how the vehicle is driven, this can and will become catastrophic. I have seen so much fuel in engine crankcases before where valve lifters would bleed down the engine would barely start and run.

And how are your shops determining if there is an elevated amont of fuel in the oil? Oil analysis? My last oil analysis indicated I had 1% fuel in the oil, while not a great amount or anything to be concerned about, this oil had less that 3000 miles and over 90% of the driving was done on the highway in lengths no shorter 2 hours in length. No Auto Stop/Start and DFM is disabled. I would hate to see the fuel percentage in a vehicle that was used for short, in town trip of 10-20 minutes in length with the Auto Stop/Start and DFM fully functioning along with using the remote start for engine warm ups at idle.