Recommended oil from BMW E53 Diesels is 5w30, not 0w30 or you can use a 0w40 weight and then again, it depends on the location your are in.

0 in cooler/cold temperature areas would mean the oil is thinner oil at start up and why Castrol recommend it for you area for winter.

I presume you did the filter as well when you did the oil?

The only other thing is that it might have needed an oil change for a while.

Don't follow BMW's long life oil theory either. I do mine every 7000km (roughly change for summer, then Winter) for piece of mind, not 15K+ km as recommended by BMW.

You just need to do a search and you will find a lot of debate about what oil should/can be used.

I tend to stick with BMW recommended and only use Castrol myself. Any oil that meets the minimum BMW specs , will be OK.

You wont do any damage with the 0w30 but for older/high mileage engines, usually people recommend a 0w40.

There's my 2 cents (pennies) worth.

Rob

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2005 3.0D, Black on Black.