My oil was running low on my 1.4 8v fabia (55k miles) so I put in the oil from my last car, which was 20w/50 grade. I wasn't aware that the grade of oil was that important... will it be fine or should I drain it and fill it with the correct grade? (I believe 10w/40)

jus on topups mate i dont think it matters.

billy

I would have thought it depends on what type of oil is its I.E Mineral, Semi Synthetic or Fully Synthetic.

I wouldn't recommend mixing different types at all.

20/50???????

Haven't used that in about 15 years..... and even then it was in an A series I didn't haver the money to get anything else for. I wouldn't even put that in my lawn mower these days. As long as you didn't use much you may be ok but what you need to realise is that modern (An by this I mean anything designed in the last 25 years) engines run much faster and hotter in certain respects meaning the oil is sometimes under much more strain and pressure. This can cause the oil to degrade significantly if it's exposed to these condiditons and not up to it meaning it's not providing the protection or lubrication is should do which will lead to things like your tappets (Which are probably hydralic) and you cam lobes to wear prematurely.

I would say if you used more than 1/2 a litre you need to change it.

I did put in more than half a litre, and now when driving i can hear what i think are the tappets grinding... Not nice. I'm definalely going to change the oil. What oil do you reccomend?

I would check the manual. It's not the grade thats so important it's the spec. You manual will tell you what spec it needs. Do a search on here it should be covered somewhere

I wouldn't have thought a top-up would make that much difference.

If it bothers you, get the oil and filter changed though.

Yeah I changed the oil today just to be on the safe side. Cheers