Q: Should I buy or is it too risky? 2003 BMW 530i

Hello - the ad appears to be gone, so perhaps you already bought it?! I wouldn’t blame you if so. As a long time E39 owner, they are an excellent sport touring car, especially if more than 2 passenger capability is required. All else being considered, buying a 6-cylinder BMW with a blown head gasket of this vintage is generally a safe move. Blown head gaskets are common with advanced mileage and age, since BMW used water pumps with plastic impellers on E39 engines, which tend to disintegrate with no warning, and instant overheating as the result. The engines seem to survive this event most of the time without long-term problems. I recommend a pre-purchase inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs. You will then buy, or not buy, with confidence - knowing the real issues to be faced with your purchase.