I have an 08 Volvo s60 with almost 50K miles. It has the 2.5 turbo. Each of two used oil analysis suggested that there was some fuel dillution. Less than Blackstone's thresholds in each case, but there nevertheless. In a recent thread there was some discussion as to whether running premium fuel could lead to fuel dillution. My owners manual suggests that anything over 87 octane is ok but that 91 is preferred. I run premium which is 93 octane where I live. My question is the following. Is it possible that the premium fuel caused the fuel dillution? Is it time to try mid range 89 octane?
Question about fuel dillution
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Stick with the higher octane when running a turbo ALWAYS.
If you lower the octane and exercise the knock sensor, your fuel dilution will be worse. Pulling timing and adding fuel are cures for preignition/engine knocking and adds to fuel being unburned and dumped... into your oil.
Make sure your cooling system is working properly. Get a new thermostat if yours is over 50k or 5yrs old. Run an occasional bottle of FI cleaner to keep the injectors even flowing among each other. Replace the air filter in timely intervals. Uncork the exhaust so that engine can exhale easier.
If you lower the octane and exercise the knock sensor, your fuel dilution will be worse. Pulling timing and adding fuel are cures for preignition/engine knocking and adds to fuel being unburned and dumped... into your oil.
Make sure your cooling system is working properly. Get a new thermostat if yours is over 50k or 5yrs old. Run an occasional bottle of FI cleaner to keep the injectors even flowing among each other. Replace the air filter in timely intervals. Uncork the exhaust so that engine can exhale easier.
My guess would be no.
How do you operate this vehicle? How long are the typical trips? How long was the trip right before you took the sample?
In general, turbo motors can run rich at times and some gas might get into the oil. I'd say it's fairly normal and no need for concern unless the % is very high.
How do you operate this vehicle? How long are the typical trips? How long was the trip right before you took the sample?
In general, turbo motors can run rich at times and some gas might get into the oil. I'd say it's fairly normal and no need for concern unless the % is very high.
Thanks for the suggestions. The air filter is good, it seems that the Volvo dealer changes it all the time. I'll ask them to check the cooling system including the thermostat next time I'm in the shop. I'll also use some injector cleaner, Chevron if I can find it.
What do you mean "uncork the exhaust.
Thanks again for your suggestions.
What do you mean "uncork the exhaust.
Thanks again for your suggestions.
When I posted the uoa, people asked me how long the trip was before I took the samples and I can't really remember. The samples were taken using the vaccum pump that Blackstone sells. My driving is pretty much average. I don't really push the car hard.
Well, it makes a difference whether you drove it for 5 minutes or for 35 minutes before you shut off the engine.
Very doubtful that 91 octane over 87 could cause increased fuel dilution. It is normal for turbo engines to show slightly higher dilution, especially if the engine has DI like mine, The important thing is the wear levels and not a small amount of fuel dilution. The reason we ask about your driving, is that any engine will show slightly higher fuel dilution, if lots of short drives are involved, especially where the oil does not reach full operating temperature for 20+ minutes. Ed
Higher Octane does not increase fuel dilution.
The reason owner manual suggests 91 is preferred is some states such as California the premium is 91, we don't have 93 here but many states such as yours have 93. I would use 93 without worrying. If you like to save some bucks, fill your tank with 1/2 93 and 1/2 89 so the final is 91.
The reason owner manual suggests 91 is preferred is some states such as California the premium is 91, we don't have 93 here but many states such as yours have 93. I would use 93 without worrying. If you like to save some bucks, fill your tank with 1/2 93 and 1/2 89 so the final is 91.
Originally Posted By: unDummy
Stick with the higher octane when running a turbo ALWAYS.
If you lower the octane and exercise the knock sensor, your fuel dilution will be worse. Pulling timing and adding fuel are cures for preignition/engine knocking and adds to fuel being unburned and dumped... into your oil.
I've been burning 87 octane gas in my turbo Volvo for years and many tens of thousands of miles...currently at 191,000. My used oil analysis reports show no fuel dilution.
I do change the thermostat every time I renew the coolant. If memory serves, a normally aspirated engine in these cars takes a 90°C 'stat, and a turbo engine takes an 87°C 'stat.
Stick with the higher octane when running a turbo ALWAYS.
If you lower the octane and exercise the knock sensor, your fuel dilution will be worse. Pulling timing and adding fuel are cures for preignition/engine knocking and adds to fuel being unburned and dumped... into your oil.
I've been burning 87 octane gas in my turbo Volvo for years and many tens of thousands of miles...currently at 191,000. My used oil analysis reports show no fuel dilution.
I do change the thermostat every time I renew the coolant. If memory serves, a normally aspirated engine in these cars takes a 90°C 'stat, and a turbo engine takes an 87°C 'stat.
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It is not uncommon to see fuel dilution in Turbo Charged Cars. Especially Japan/Euro versions of cars sold here. Our lower quality gas (IMO) and lower octane levels cause the ECU to dump more fuel in to keep knock down.
You could get your car tuned on our fuel here and the fuel issue should be resolved, but if your car is still under warranty you may not want to do that.
Also, many folks don't drive their cars PRIOR to taking the sample. Drive your car for at LEAST 20 minutes THEN take the sample. If the engine is cold, or just started to be moved to the garage for the oil change, the car runs richer when cold and may cause too much fuel to be left in the oil. Driving it for 20 minutes burns off any excess fuel and gives a more accurate number.
YES USE THE 91!!!!
Use a good quality Synthetic Oil and change every 3-5K miles and you will be fine.
Jeff
You could get your car tuned on our fuel here and the fuel issue should be resolved, but if your car is still under warranty you may not want to do that.
Also, many folks don't drive their cars PRIOR to taking the sample. Drive your car for at LEAST 20 minutes THEN take the sample. If the engine is cold, or just started to be moved to the garage for the oil change, the car runs richer when cold and may cause too much fuel to be left in the oil. Driving it for 20 minutes burns off any excess fuel and gives a more accurate number.
YES USE THE 91!!!!
Use a good quality Synthetic Oil and change every 3-5K miles and you will be fine.
Jeff
Naw... it's not the premium fuel.
In fact, it may help in a left handed way!
Turbos often are set rich to help cool things. This is common with street tunings from the mfrs.
It's the way it is unless you get a chip. Then you get more power, economy, and not as much fuel wash.
In fact, it may help in a left handed way!
Turbos often are set rich to help cool things. This is common with street tunings from the mfrs.
It's the way it is unless you get a chip. Then you get more power, economy, and not as much fuel wash.
Thanks for all of the replies. I will check the thermostat issue next time it's at the dealer. i tried the 1/2 and 1/2 with 93 and 89 but decided it's too much trouble. I'm just going to use the 93 and not worry about it as Blackstone indicated that it wasn't a problem.
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