Castrol Edge 5W 30 4 Litres £27.99 !!!

[sakimano]

frankly it shouldn't necessarily be 5w30 (or 5w40)

It should be an approved Audi oil. Audi puts out a list o acceptable oils.

Castrol, (thought by most oil analysts to be middle of the road) is the one that pays Audi (and BMW and I believe MB via sponsorship to be the oil of choice), however there are a bunch of others.

Motul Xcess8100 5w40 gets top marks and is the most popular choice. It's French and Castrol is English, so I reckon that may be one reason more folks here on rs246 prefer Castrol. I frankly just want the best oil for my car.

[PetrolDave]

frankly it shouldn't necessarily be 5w30 (or 5w40)

Have we ever got to the bottom of why Audi UK prefer 5w30 but AoA prefer 5w40?

I'm sure it's been discussed many times on many RS4 forums, but I can't remember seeing a well thought out and proven reason for the difference?

[neilparf]

If you look at it that way, then Castrol, Fuch etc are all VW 504 or VW 507 approved/Audi approved and that's the end of the Audi 'acceptable' oils list.

Unfortunately, it is 5w 30 and that's what UK dealers and UK Audi is saying to put in the RS4. I kinda want to follow that advice and choose the best I can find/buy within these parameters.

Stray outside of those parameters and leverage any goodwill from an Audi dealer/UK would be hard enough should they find it's not 5w 30 when all UK Audi bodies say this is recommended...

I prefer certain Race oils but they aren't VW approved so as long as my choice sits comfortable with me and is within those two parameters, I'm happy.

Besides, if you change at 10K anyway and as long as it's a worthy brand...

Personally I prefer Fuch over Castrol...

[sakimano]

5w30 vs. 5w40 is strictly a difference in weight or viscosity as I understand it.

The first number with the w is the winter rating. The second number is the viscosity at 'normal' temperatures. Basically 40 is thicker, heavier. Handles heat a little better. The Rs4 is definitely a hot running engine, especially when you visit the 8 on the tach regularly. It runs at 100 celsius pretty much on the regular, and sees 110-120 celsius pretty easily if you're pushing the car.

[PetrolDave]

5w30 vs. 5w40 is strictly a difference in weight or viscosity as I understand it.

The first number with the w is the winter rating. The second number is the viscosity at 'normal' temperatures. Basically 40 is thicker, heavier. Handles heat a little better. The Rs4 is definitely a hot running engine, especially when you visit the 8 on the tach regularly. It runs at 100 celsius pretty much on the regular, and sees 110-120 celsius pretty easily if you're pushing the car.

Having had a senior position in the Engineering Department of a well known sports car manufacturer I'm well aware of the meanings of the oil rating system, it's the difference between the position of Audi UK ("use 5w30") and AoA ("use 5w40") that I was asking about.

Is it just down to average summer temperatures in some parts the US & Canada regularly exceeding average summer temperatures in the UK?