Fuel Dilution

[byez]

Are thicker oils more resistant? Is synthetic more resistant than dino when comparing similar weights?

Say you start the car in the morning and drive two blocks. Have to make a quick stop and the car is nowhere near operating temperature yet. Turn the car off or idle it during a quick stop?

 

[browning300wsm]

oh boy here we go again ....use synthetic oil 5 w30 [any make of your choice] turn the car off ..

 

[heathenbrewing]

No.

No.

Id let it idle if the stop is 60 seconds or less.

 

[INDYMAC]

Originally Posted By: byez
Are thicker oils more resistant? Is synthetic more resistant than dino when comparing similar weights?

Say you start the car in the morning and drive two blocks. Have to make a quick stop and the car is nowhere near operating temperature yet. Turn the car off or idle it during a quick stop?


Unfortunately, your driving habits will continually dump more and more fuel into your oil than you will ever be getting rid of from the evaporative effects of driving for extended periods. Most manufacturers recognize this phenomenom and categorize your driving habits as severe for maintenance purposes. They usually recommend 3-4K mile OCI to help your situation. That's what I would recommend you do until you have done some UOA's through Dyson Analysis.
Feel free to try different types, brands and viscosities of oil. That's what the rest of us are doing to find the Holy Grail. Try to avoid fuel additives until the tank just before your next oil change. That may help some too. Good luck!

 

[benjamming]

Originally Posted By: byez
Turn the car off or idle it during a quick stop?


Are you going into a store or something? I guess then it would partly depend upon which part of town you make the stop.

 

[mechtech2]

Fuel dilution is not a problem with modern cars unless something is broken.

 

[Tones]

Not necessarily. I'm no expert, but sometimes the ECU is intentionally programmed to run the car rich to heat up the catylytic converter and keep NOx emmissions lower. Meeting current air regulations is a tricky business and there are tradeoffs.

 

[BuickGN]

Originally Posted By: mechtech2
Fuel dilution is not a problem with modern cars unless something is broken.


This is what I have thought. I was under the impression that, assuming the car is running right, fuel dilution problems went away with carbs and points and condensors.

The post above mine might have some validation. I know my TL as a ULEV car runs very rich when first started (and I'm assuming only when there's no heat in the motor or convertor)to light off the convertor quicker. My car gets driven for a minimum of 30 minutes every time it's started so I'm not worried but maybe for some who do one or two dead cold starts a day with a 5 minute or less run time could see problems.

 

[ekpolk]

Originally Posted By: mechtech2
Fuel dilution is not a problem with modern cars unless something is broken.


That's not always true. My oil expert is of the opinion that certain cars, for various reasons, do suffer dilution even when all else is normal. The Prius seems to do it in many examples, including alas, mine. Based upon some further sniffing around, it seems to be a byproduct of some complex programming in the ECUs of cars that are trying to satisfy many competing demands, such as emissions compliance, driveability, economy, durability, etc.

 

[kokopelli]

Originally Posted By: mechtech2
Fuel dilution is not a problem with modern cars unless something is broken.


I'm of the opinion that Fuel Injected engines are more prone to dilution than the old carburetor cars...; of course, this is only my opinion, and as always, my opinion is usually wrong.

 

[bruce381]

Originally Posted By: ekpolk
Originally Posted By: mechtech2
Fuel dilution is not a problem with modern cars unless something is broken.


That's not always true. My oil expert is of the opinion that certain cars, for various reasons, do suffer dilution even when all else is normal. The Prius seems to do it in many examples, including alas, mine. Based upon some further sniffing around, it seems to be a byproduct of some complex programming in the ECUs of cars that are trying to satisfy many competing demands, such as emissions compliance, driveability, economy, durability, etc.


True that is one reason oil MUST be changed at a resonable OCI
cause lube engineers KNOW fuel, water, dirt, [censored] gets into the oil in use.
bruce

 

[lewk]

Tones

Nox is a byproduct of unburned fuel(hydrocarbons) and sunlight in the atmosphere. Its the hazy brown color that alters that azure sky look we enjoy so much. Running rich is just your cars way of saying It has not reached the preferred closed loop operating mode.O2 sensors have a heater circuit to facilitate this process. This is why its a good idea to drive off once your idle stabilizes, usually by the time I adjust the radio controls and get the seat belt on. Prolonged idling beyond this point is bad for the budget and the atmosphere.Just take it easy and don't "stomp" on it if at all possible.

 

[BuickGN]

Originally Posted By: lewk
Tones

Nox is a byproduct of unburned fuel(hydrocarbons) and sunlight in the atmosphere. Its the hazy brown color that alters that azure sky look we enjoy so much. Running rich is just your cars way of saying It has not reached the preferred closed loop operating mode.O2 sensors have a heater circuit to facilitate this process. This is why its a good idea to drive off once your idle stabilizes, usually by the time I adjust the radio controls and get the seat belt on. Prolonged idling beyond this point is bad for the budget and the atmosphere.Just take it easy and don't "stomp" on it if at all possible.


In some cars like my ULEV car, it's purposely run rich to light off the cat quicker. The cat is bolted straight to the head and that coupled with the rich mixture causes it to light off very fast.

 

[edhackett]

lewk, NOx (NO+NO2) is produced directly in the combustion chamber. The heat of combustion is enough for N2 and O2 from the air to react to form NOx. What you are describing is photochemical smog, which is the secondary reactants of NOx and VOCs. NOx also has a role in ozone formation.

In a catalytic converter oxidation of NOx to N2 and O2 is favored under rich conditions. Oxidation of CO and hydrocarbons to CO2 and H2O is favored under lean conditions. In order to meet NOx emission mandates, the car makers must run a delicate balance of mixtures in the converter. Some may richen the mixture artificially to lower NOx during part of the driving cycle to insure NOx is low on a grams/mile basis. Maybe others can elaborate.

Ed