We have an '82 1.6 Petrol T25....about to head off on a loooooong journey, and ive just noticed the oil is a bit on the low side.
I'll not be able to do a complete oil change (have never done one myself anyway

Firstly, is it OK to do this? I dont know what oil was used before, so does that matter?
Secondly, what oil would you recommend? Preferably something i can pick up in the likes of Halfords.
Thanks again in advance!!