I was told that I should use Castrol SAE 5W 30 type oil. I have Chevron SAE 5W 30 grade oil and was wondering if there is any difference in viscosity and quality of oil brands for my Audi vehicle?
The car requires a 5w40 not 5w30. I think by default 5w40 usually labeled European blend or spec, is synthetic and also meets a certain VW/Audi spec. Just confirm the VW/Audi spec and get proper grade.
5w30 is not acceptable.
It’s not just the weight of the oil, the Germans, in particular, are requiring special oils for their cars. You need to look in your owner’s manual, find the specification for your oil, and use oils that meet that specification, along with being the correct weight.
Any two oils with the same SAE number, such as 5W30, have the same viscosity by definition! Agree that a German turbo engines, in the absence of any other info, need the very best oil. A 5W40 synthetic makes sense for this particular engine. In fact, it makes sense in any turbo engine.
As far as quality is concerned, the full synthetics, such as Mobil 1, perform better at very high temperatures and very low temperatures. As far as additives go, the the same API and ASTM designation, such as SL, or SM, would have the same additives and subject to the same tests, regardless of brand.
In short, just use what your OWNER’S MANUAL calls for and change oil twice as often as the book calls for.
Here’s a list from Audi for the oils that meet their various specs. You still need to find the specific spec for your A4 in your owner’s manual: