I'm looking at a 530iT wagon locally with 165,000 miles. I'm wanting to know what problems I should be looking for. I've read that the cooling systems are suspect at this mileage. I've read up on the Nikasil/Alusil block compositions. This would be my first bmw purchase and I'm not overly familiar with the quirks of the manufacturer. How much should I expect to have a pre-purchase inspection done by an independent BMW mechanic? Are there any engine block casting numbers that would verify which composition the block is made of? Any advice or information would be greatly appreciated. Thanks.