Just gone to check my oil, first time in a while to be fair and the oil cap is gunked up :(

It's an 55 plate with 93k on the clock to give you a rough idea of where it is at.

I've recently (last 6 months or so) started to do shorter 4 mile trips in it, the water is getting up to temp just before i park up. Before I was running 15-17 miles, could it just be doing the short trips causing it? Or the head going or something else?

Love my octy :( don't want it to die!

its the short trips, nothing to worry about. The engine does not get hot enough to burn off the condensation, so the mayo forms. Take the car for a couple of good long runs and it should be gone.

Thanks, I've cleaned it up for now, going on a long drive see if it gets worse.

only a problem if you are overheating or losing water, anything else is as above - condensation

+ 1 condensation, very common for short journey driving

go for blast on a run and you will be fine an get a Oil Catch Can fitted as this will fix the short journey driving oil gunge

then you can drain this crud from it every few months

Although your dash says 90, it takes about twice as long for the enigine to actually reach 90, it's at about 70 when the needle hits the middle.