Used engine oil colour - dirty green??

[proximity]

I have a GPZ 600 as a project bike (ive never ran it but was told it was running before it was stripped).

I drained the oil today and it is supposed to take 3 litres, but 5 litres of dirty greenish oil came out.
Like the kind of green you get as army paint. It looked shit and runny, i thought maybe the head gasket is gone and water has got in, but the water i drained is clear as day, and usually contaminated oil is milky.

What do you reckon?
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2004 Aprilia Tuono

[stinkwheel]

Well, starter for ten. Water and oil are immiscible.

So, you would get one of two effects if two litres of coolant had got into three litres of oil inside the sump of your engine.

a) Emulsion. The liquid would be opaque, like mayonaise.
b) Seperation. You would get a layer of oil floating on top of a layer of water.

If you have neither, it isn't coolant but something else (I have no idea what, petrol from a leaky needle valve?)

[proximity]

The oil does smell like petrol pretty bad to be honest.
Is it possible that it has leaked into the oil somehow, and what other problems could this cause, or will it be ok once the oil is changed and carbs fixed?

Its also possible that some idiot put 5 litres of oil in by mistake (the sight glass is shit)
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2004 Aprilia Tuono

[Grubby]

Sounds to me like someone used Duckhams before you got the bike.
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I am me & you are he & we are all together. See how they run like pigs from a gun!

[stinkwheel]

If it is petrol, it has got past two points where it should really have stopped.

The first is the vacuum fuel tap. The second is the needle valve in the carb(s).

If it has sat for a long time, any leak could be very slight and slow and may even be down to simple lack of use.

If it were me (this is my speak for 'not by the book but what I'd do on my bike'), I'd change the oil and possibly strip and clean the fuel tap (assuming it is one you can take to bits).

I'd then give it a whirl. A functional fuel tap should stop petrol getting into the carbs when the engine is stopped anyway. If you are still having problems, then take a look at the carbs.

I suspect a lot of modern bikes have a slightly leaky needle valve(s) anyway, it's just no one notices because of the fuel tap.

If you are worried about contamination in the oil, I'd change the filter, give it a fill with cheap oil then change it for good stuff (with a second new filter) after 50-100 miles.

Conventional wisdom would have it that you would flush it with thin flushing oil, but oils don't work the same way as they did 30 years ago. They tend to hold any muck in suspension nowadays and rely on the paper filter to catch it rather than sludging it into the bottom of the sump. By running for a bit then binning the filter, you are much more likely to remove any contaminants than with a simple flush.

[proximity]

Thanks for the help.
I dont actually have the fuel tap because it has no tank as i bought it as a rolling chassis with engine to do a swap into my bike.
Ideally i want to get it spot on before i put it in so i may change the head gasket and do the valves etc.
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2004 Aprilia Tuono

[Heckthusula]

[proximity]

I know you can get coloured oil but this was definately mixed i can see the swirls, it looks like a swamp.
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2004 Aprilia Tuono

[stinkwheel]

In that case, it is possible that someone just filled it up to the top with whatever oil they had to hand if they knew it was going to be laid up for a while to stop internals going rusty.

[Paddy Blake]