oil on spark plugs

[tucker]

I have just changed the plugs and air filter on my 1.6 16v petrol.

I noticed before I removed the plug on the 4th cylinder that there was some oil sat in the plug well. I mopped it out and then removed the plug which also had oil on the thread and tip. 

A couple of the other plugs had a very small amount of oil on the threads too but not much. 

It seems from google to be likely to be the valve seals? I don't know much about these or how much effort is needed to replace them or if it's urgent to do it. 

My car is LPG and I have of late had some problems with the injectors as they were gunked up. I've now sorted that, but prior to this I was having problems with it misfiring when it first went onto LPG because the injectors needed to warm up before they ran smooth. I don't know if this could have had any bearing on the oil being there or if it's unlinked? 

Anyone out there who can share their views or experiences?

[ddb]

What mileage?

[tucker]

It's done 115K on a 2004 plate.

[V6BOY]

Sound like leaking rocker cover gasket filling the spark plug wells with oil,try that first will be a very cheap fix.

[tucker]

Hi
I have checked the rocker cover and there's no signs of any oil leaks, plus the plug well stands proud, so any oil from the rocker cover couldn't make its way in there.

[Jed Clampit]

How tight were your spark plugs to take out and have you or the past owner had them out before if so how many time plus if they were over tightened at some point in the past  the seal's may have bean crushed and leak under compression so fit the new plug's keep an eye on them odd's on there will be no oil around them . 

[tucker]

Cheers Jed

I change them myself every six months. So last time was around Sept 14.

LPG likes a good spark so twice a year works best.

I find they often work a bit loose, so it may well have been a bit slack, although I make them tight on fitting.
The new ones are in tight, so I will see in a few weeks and remove the worst one I guess.

[ddb]

I hear so many stories of spark plugs stripping threads or coming loose that I torque them whenever possible 18ft-lbs on these I believe.

[ffrenchie]

Is the oil level dropping significantly on the dipstick ? Why change the plugs if they are still working ? LPG is kinder to engines than petrol and they should last a lot longer we used to use LPG fork trucks and they were never changed in them. Do you still have the EGR in place ?

[tucker]

No it's not dropped significantly, but is just a touch below the top marker, so has lost a little.

The recommendation with LPG is regular renewal of the plugs as it needs a good spark, so I change them and the oil every 6 months as they are £10 a set.

There's no EGR on this engine as far as I am aware.