Does the BMW X5 have a timing belt or chain?

The BMW X5 does have a timing chain. The coolant needs to be replaced every 60,000 miles. Your air filter needs to be replaced every 15,000 to 30,000 miles. The spark plugs need to be changed every 100,000 miles unless it's a copper one. A cooper spark plug needs to be changed every 30,000 miles. You will come into many problems with an engine. A gasket may be loose and that needs to be tightened up. A spark plug may pop off, causing engine issues. You can have oil leaks and those need to be repaired as soon as possible. There could be excessive oil use, requiring the oil to be replaced sooner than expected. A really serious problem is the engine overheating. This may lead to fires and the car exploding.