I understand the issue with red-hot turbos carbonising the oil if they are switched off immediately after a motorway journey, especially with diesels like ours. How long should they be idled before switching off? If we have a five minute drive from the motorway on country roads, is that enough? Is it safe to switch off for brief periods before restarting? I'm thinking about stops at motorway service areas for a drink - about 10-15 minutes, or for a meal - about 25-35 minutes. Would either of these cause problems?