I have a new car! Well, an old second hand Escort, at least. Everything is in good order, but I can't find out how to put oil in it - sorry, I'm such a numpty with these things! Suffice to say, I will be getting a Haynes manual in the future, but I was trying to find the oil filler cap earlier and can't see where it is. Could anyone tell me please? Or point me to a site that has nice pictures so I can work through it myself?

Also, as it's a 1990 Escort (1.3 Bonus 3 door hatchback), with over 100K on the clock, what sort of oil should I be using? I want to put the right stuff in.
Any other problems that these cars are prone to, would also be useful to know as well. The underfloor's okay in this one, it has a full MOT until September, and the only rust is a tiny bit over the rear wheel arches which I'm told isn't structural. Overall, it looks like a nice car to me, the engine seems to run okay (when I manage to figure out what revs it needs and stop overdoing it!) and although a bit tatty on the interior trim, it's nothing I can't live with.
I also seem to be having trouble opening the boot - none of the keys I got seem to work in the lock!