You guys are awesome. About four months ago, I went for an oil change at a Mobile 1 station. My 4.8is has 150k miles and I thought I should start using "the good stuff" so I went with Mobile 1 full synthetic 0W-40. A few weeks later my engine bay was covered in oil. I took it to the dealer to access the damage. You guessed it. Every seal you can think of was leaking oil. The total price to repair was nearly 10k. They tried to sell me on a new X5 and I passed. I found a top notch INDY that did the job for half of that plus some extras. No leaks but it was smoking blue after extended idle. More research reveals the dreaded valve seal/guide problem. Estimate to repair: 6k. After reading this thread I decided to either go with a 5W40 oil to see if that helped. I never knew about Liqui Moly but decided to drop in a can of Motor Oil Saver with the existing 5W30. A couple of weeks later.. no smoke. None. It's gone. Car runs smoother and quieter. Many thanks guys. I'm going to keep this baby going past 200k and maybe 250k.