Fuel in oil, any suggestions?

[T-Keith]

Hi, I'm new here. It's been a while since I owned a 60deg, but my sister has a 2000 Malibu with the 3100 V6.

I recently had an oil analysis performed because I've heard on a couple message boards about intake manifold problems on the 3100/3400. I posted it below. It does seem to have a slight antifreeze leak, but the main problem is the fuel contamination. The oil was 3.5% fuel! And this was a fairly short interval. I checked the fuel pressure and it was right on, with no drop in pressure after 15 min. The injectors and fuel pressure regulator don't appear to be leaking. She says it runs great, so I'm not sure where this fuel is coming from. It's winter so a lot of cold starts. Does anyone else have an oil analysis so I can compare?

Thanks,
-T

[Quinky]

RE: Fuel in oil, any suggestions?

on your sheet is says it should be 1.0... so obviously you are over... usual causes for fuel in the oil would be, excessive blow by from work out rings, or you are running way to rich..

[adamg]

RE: Fuel in oil, any suggestions?

This happened to my 89 cavi..turned out to be a combination of a week ignition and bad valve stem seals.

[Juglenaut]

RE: Fuel in oil, any suggestions?

I'd say Molybdenum is rather high is comparison to the calcium.

Which yield me to believe there is a fuel problem, and or worn rings may be made out of Molybdenum alloy combination.

It is also possible to have a few intake valves not seating right.

weak ignition on such a new ECM will throw a code at about 10% out of parameter.


Molybdenum uses

http://www.imoa.info/Default.asp?page=74

I would say worn block in certain cylinders needs to be boared and rehoned, or reringed.

Aussumtion:

Molybdenum at 91.1 percent for mileage
Calcium at 58.6 percent for mileage.
Iron at 62 percent. Practical amout is about 80 percent since only iron sulfates or oxides can be dissolved in oil so elemental iron is to heavy.
Aluminum is rather high as well at 75% again practical amouts for heavy metals are higher.

[George]

Too many cold starts?

Exactly what kind of driving was done just prior to the oil being pulled for this sample? If this car were running as badly as people think to get this much fuel in the oil your ?check engine? light would be on because the computer would sense the cars is not running right. I think there were several cold starts just prior to the oil sample being pulled. Especially this time of year the car needs to run quite a while to get the oil hot enough to burn of excess fuel in the oil from a cold start. Your antifreeze comes up to temperature a lot faster than the oil, so even if your temperature gauge shows normal operating range the oil takes longer to get hot. My guess would be several cold starts occurred in a row without enough run time to burn off excess fuel just before the sample was taken. Is this possible?

[T-Keith]

The car was driven 15 miles before sampling. She said it has never started hard or flooded. No codes. The car only has 70,000 miles. The wires were replaced about 5000 miles ago, the plugs looked fine then.

Juglenaut, do you have any UOAs you can share? Moly is an oil additive so it's not necessarily a problem.

-T

[T-Keith]

Just noticed this might be in the wrong section, moderator please move it if it would be better elsewhere.

thanks for the help,
-T

[ikessky]

Couldn't fuel be getting into the oil from a leaky lower intake gasket also though?

[Juglenaut]

Your sheet referes to elemental Molybdenum not a derivative or compound of Molybdenum, and yes Molybdenum is used in casting blocks.

Common compounds of Oil additives:
Molyvan A
Molyvan L
Molyvan 807
Molyvan 822
Molyvan 855
Molyvan 856B
Molyvan 2000

All of these are compounds and are not elemental, these can be tested for but are not picked up on a tester by practical means requires spectrochemical analysis as well as microscopic debris analysis. Also moly most times is in Full-synthetic oils. Regular oils don't have moly unless spec'ed out for the oil to have it.

Moly in oil is actually bad as it can cause corrosion of brass, and copper base metals, however most engines don't use copper base metals in critical areas.

Here is some more info:

http://xcelplus.com/educational/definitions.htm

http://skepdic.com/slick50.html

I agree most times moly is in a form of an additive so is calcium as a detergent.

It also states you have 2555 miles on that sheet for the oil, if you had only 15 miles on it the numbers would be different. I would test fresh oil and then test used oil to compare. Even if the oil had 15 miles on the oil it is used, it is used as soon as you put oil in the crankcase.

More reads:

http://www.powerandmotoryacht.com/engines/0104oilanalysis/

Says potassium can mean you have a faulty gasket or possibly a cracked cylinder head, although potassium can also be an additive.