Thanks so much for getting back to me. I spoke to the garage and they have said they have put in 0/30 fully synthetic. Do you think its best I drain my oil and put in a better one?
With 5W-30, you either buy conventional, blend, or full synthetic. Full synthetic will have the fewest VI additives. Conventional the most. Reason is, full synthetic molecules maintain their viscosity better. You can either add a better additive pack to conventional oil, or blend in some synthetic, to get the desired multigrade properties.
0W-30 is almost ONLY available in full synthetic. It’s very difficult (and expensive) to design additives that can beef up a very thin oil (at room temperature) to stay thick enough at operating temperature.
So, which to choose?
If it were my car, built in the last 10 years, the place to start is the oil cap. What does it say? For an American or Asian (Japanese or Korean) car, it’s likely to say 5W-20, 5W-30, or for very new cars, 0W-20.
Next place to visit is your owner’s manual. It’s in your car, and also most likely on-line, just search “year”, “make”, “model” and check the specs. My car, for example,
above is a piece from oil descriptions notice the 0/30 fully synthetic comment, ie at start up that oil is thinner than a 5/30 oil which is what the recommend. thinner oil can cause some by product issues with changing pressure and flow maybe and if a worn engine this would amplify any effects,, by worn engine 40k plus miles could be that. i hive had a lot of discussions on here in the past about oils and using thicker or thinner or fully syn or part syn oils, and i stand by what ever the makers and designers of a engine say you should use is what should be used,, i've seen the aftermath of vw PD engines after people used a non PD oil in them and camshaft fail after 60k, i would contact mini main dealer ask them if in any country would 0/30 oil be used,, maybe in a -10 to -50 it would be, i've always used 5/30 fully synthetic in prince engines,, even the diesels are 5/30 but low saps as have a dpf filter use nything else and it ends badly on them turbo failures