Oil Suggestion for Engine with Fuel Contamination?

[silversapphire]

Howdy Yall!

I'm the owner of a 1994 Toyota Camry V6 that currently has 88k miles. I've owned the vehicle since 69k miles. Sometime between 72k and 79k miles, the oil started to become contaminated with fuel, as is shown from used oil analysis a while back. In addition, the dipstick smelled moderately of gasoline. The used oil analysis showed 1.5% fuel contamination, but luckily no increase in wear metals compared to the sample with no fuel contamination.

I blamed the fuel contamination on short trips/winter weather, as I frequently made 5 mile trips. However, my driving pattern changed; For my most recent oil change, my average trip was about 14 miles and the dipstick still smelled of gasoline.

I asked two Master ASE mechanics about the issue, and they both said that it was normal for an older engine and that they wouldn't be able to find the issue short of an engine teardown. They both recommended that I run the engine as is.

Is there any oil out there with an additive package that can specifically deal with fuel contamination or reduce blow-by? If there isn't, should I run 5w-40 oil since the fuel contamination lowers the viscosity of the 5w30?

Many thanks-silversapphire

 

[spasm3]

I would make sure the thermostat is working and bringing the engine up to temp, i might go ahead and replace he o2 sensor. O2 sensors can get slow/lazy before they start throwing codes. With a 14 mile trip the dipstick should not smell of gasoline. Are the spark plugs and wires in good condition( distributor cap and rotor if applicable) if they have never been changed , i'd do that. Amsoil has a hdd 5w30 oil ( heavy duty diesel) . The hdd oil should have more detergents and handle the fuel better. Its also probably close to a 40wt anyway.
I'd really focus on fixing the fuel dilution rather than
fixing it with oil.

 

[artificialist]

Originally Posted By: spasm3
I would make sure the thermostat is working and bringing the engine up to temp, i might go ahead and replace he o2 sensor. O2 sensors can get slow/lazy before they start throwing codes. With a 14 mile trip the dipstick should not smell of gasoline. Are the spark plugs and wires in good condition( distributor cap and rotor if applicable) if they have never been changed , i'd do that. Amsoil has a hdd 5w30 oil ( heavy duty diesel) . The hdd oil should have more detergents and handle the fuel better. Its also probably close to a 40wt anyway.
I'd really focus on fixing the fuel dilution rather than
fixing it with oil.

+1

And at the age of your car, I am wondering if a fuel injector doesn't close all the way, and drips excess fuel when the engine is shut off.

 

[expat]

Does it consume oil?
Have you done a compression test?

The engine has low miles for it's age, I'm wondering if you have stuck rings.

 

[Recalculating]

Coolant temperature sensor?

Constantly running in open loop.

 

[spasm3]

Originally Posted By: Recalculating
Coolant temperature sensor?

Constantly running in open loop.


Excellent point, thats a problem on s series saturns, worth trying!!

 

[silversapphire]

Thank you for all the replies so far.

@spasm3: I have no idea when the previous owners changed the spark plugs. I was planning on changing them once the weather warmed up

The 1994 1MZ-FE is distributorless, and has no wires as it has coil over plug ignition. I'm not not sure if it's any indication of the thermostat, but the coolant gauge in the car seems to work fine, as it starts at C and slowly climbs to the center of the gauge. I would like to fix it the fuel issue too, but was discouraged by the advice of two Master ASE Mechanics, who said it was normal. Even though it's normal I still want to fix it

@artificialist: If I had the know-how to test the fuel injectors I would, but since I don't, I'd have to pay someone to test/replace them, and labor is pricey! If it's any indication though, my car starts at the first try in the morning after sitting all night?

@expat: I change the oil every ~2500 miles, and the dipstick reads just a tick below full, so it doesn't seem to consume oil at an appreciable rate. I have not done a compression test. And yes, the previous owners did not drive it; the car must have sat for years.

@recalculating: how would I be able to tell if it's constantly running in open loop? The coolant gauge seems to work fine. There are also no CELs.

 

[zach1900]

2,500mi oci? Maybe it's not fuel contamination, maybe your changing your oil to often and are always in the boil off phase?

 

[spasm3]

I'd do the plugs then and possibly the coolant temp sensor. The suggestion of a fuel injector leaking down is a good one. I just don't believe a fuel injected engine should have fuel dilution( excepting DI of course.) If this was a carbed engine or Direct Injection then i would say its normal.

 

[901Memphis]

1.5% isn't awful and you very already confirmed that the UOA didn't show elevated wear metals which is good. I vote for you keep doing exactly as your doing unless you can find a mechanical cause for fuel dilution. I doubt any oil will handle the fuel dilution better than another, I'd stick with 5w30 maybe a HM like Maxlife or any other brand that is API SL+

 

[Recalculating]

Your 1994 Toyota is an OBD I system so there are no economical ways to see the active input of the coolant temperature sensor. I do not know if your coolant temperature sensor plays a dual role in the visual gauge and reporting to the PCM. I doubt it. However, the coolant temperature sensor may be about $20 and if it has never been changed, it's suspect. Sometimes the connection is at fault too. Look for external drips there.

I am not familiar with your vehicle but basic OBD I programming in getting the engine to efficiency would point to this sensor.

 

[demarpaint]

Originally Posted By: artificialist

And at the age of your car, I am wondering if a fuel injector doesn't close all the way, and drips excess fuel when the engine is shut off.


+1 After checking into the sensors mentioned already I would consider sending the injectors off to Trav for cleaning and him working his magic on them. It will probably be money well spent.

 

[Leo99]

Some of these recommended repairs get expensive. O2 sensors are about $50 each. If it's the rings, you'll just have to live with it or hope it clears up on its own unless you want to pay big bucks to get that fixed or try and tackle that yourself.

I don't know how much you paid for the car but you quickly reach a point of throwing good money away at bad. If the car runs fine and 2 master mechanics say it's normal, then drive the dickens out of the car and then hope for the best. You might get another 100k miles out of the car before this issue becomes a problem.

If you don't want to pay for diagnostics, you surely don't want to throw parts at it hoping you get the right one.

I'd change the coolant. Maybe send that out for analysis, too.

 

[Ibrahim]

Ultimately at best an oil can do is blanket the issue, if you plan on keeping the car it's best you try the suggested maintenance work by the members. Although given the low mileage I don't think a High Mileage oil is needed, any 30 grade oil will serve you well!

Do also perform complete fuel system treatment...

 

[aa1986]

First step is to try a fuel system cleaner - Techron Concentrate or Gumout Regane / All In One

After that, before spending more time and money, ask yourself what negative consequence do you have from this problem?

1.5% dilution is only an issue if your UOA showed your oil's viscosity has gone too low. Has it?

If so, step up to a 40 like you suggest. But beyond the fuel system cleaner and that, I don't think it's worth spending much more time and money on this.

 

[crazyoildude]

i agree with aa tecron make sure your thermostat is working and also listen to the exhaust and maybe put your hand over it and see if you detect a misfire.

 

[Kuato]

14 miles isn't very far. In your position I would go for a long highway drive, maybe a couple hours, then take a sample to see how the oil looked at that point.

 

[KrisZ]

I would wait for the warmer weather to show up and see how things are doing then. There is no reason to start throwing parts and money at this yet. And all oils are affected the same by fuel dilution, changing them more often until the problem is fixed, is the best solution, but at 1.5% there is no need to be alarmed.

 

[Donald]

Replace the fuel injectors or pull them and have them cleaned. Trav can help.

 

[Doog]

Originally Posted By: Donald
Replace the fuel injectors or pull them and have them cleaned. Trav can help.


This^^^^ But try a heavy dose (entire bottle in each tank) of Redline SI1 fuel system cleaner twice (2 tanks of fuel)first before you pull them. I have cleaned 2 stuck injectors that way. Then do a maintenance clean every 10,000 miles. I would also replace the temp sensor, spark plugs and maybe the o2 sensors as well.

Then give that beast an Italian tune up!!!

My oil of choice for your situation would be Rotella T5 10w30 changed at 3000 miles.