Good points JCL. But for the most part, the way the cars used is normal driving and the only ripping around it gets is during meets and the occasional full 3rd gear windout, no one here is running the engine 6k rpm half the day, like for example race engines, so i really feel alot of the things are not going to matter that much.

I do agree for example never using cheap dino store brand oil, versus a reputable full syn like mobil1, castrol, etc. There are vast differences there.

But the diesel provides more anti-wear additives, zinc and other stuff, along the weight of the oil, im sticking to 5-40/10-40 maybe will end up running this year round the 5-40, because so far the steps i have taken to reduce my smoke and oil consumption, it has made worlds of difference since it was bad compared to now..

Before i could eat a quart 600-800 miles.. Now i go for 1750+, oil smoke is almost non existant unless i purposefully idle it when hot for over like 12-15min.


Other then those points (which makes it the best option for me), it basically comes down to just changing the oil/filter frequently and its a small investment to pay versus running it real long and the risks for engine.

So perhaps an oil may not meet bmw longevity spec, but i would never care cause the only reason i ran my last full syn mobil 7k is because of some longer trips and the fact that the x holds more oil then standard cars. Normally i run full syn for 5k (granted its cheaper when the cars only req 1 5qt bottle), but its cheap peice of mind and keeps the engine working great.

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2006 X5 4.8is Fully Loaded