: FYI: Turbo engines and oil changes

04-24-2008, 12:25 PM
Here is a question that was asked in a brit newspaper, that is very applicable to owners of the new N54 turbo engines, at least to those who own the car, and plan on keeping it a few years.

It's about oil change frequency and turbo engines.

It will be very interesting to see BMW's response if the turbos start failing at about the mid-30's K miles!


Have there been any reports on defective ford turbo diesels? The turbo in my ford mondeo glx 2.0 has packed in after 37,000 miles.

Patrick Love, Carryduff, Northern Ireland

Although there are tales of failed Mondeo turbochargers, Ford have not released any technical bulletins suggesting a particular problem. However, with proper maintenance a turbo should last as long as the engine. As yours has failed at such a low mileage, ask your dealer to see if he can get some goodwill from Ford. If you have a good service history, with all oil changes at the right time, you should have a strong case.

Turbochargers do need a bit more TLC than a basic engine and there are a lot of failing units on cars old and new that could have spun on happily with a bit of understanding and consideration. And thatís not just from owners or garages. A turbocharger is a very simple machine, in essence, simply a rod with a fan fixed on each end. One fan gets spun around by the exhaust gases as they come out of the engine, which makes the other one blow extra air into the other end of the engine. More air going in means you can burn more fuel and if you burn more fuel you get more power out. The problems arise because turbochargers operate in just about the most hostile environment this side of a Top Gear tent at a Greenpeace convention. Scorchingly hot exhaust gases heat one end to almost red heat, while an inch or so away, the other end sits in cold air. The turbo spins at enormous speeds as well Ė 20,000 rpm is quite normal Ė so the shaft has to be well lubricated to keep it spinning freely, and the slightest imbalance will make it shake itself apart.

So, what keeps all these extremes from blowing it apart after just a few seconds? A good dose of clean, high performance lubricating oil. Engine oil is pumped up to the bearings in copious quantities, to keep the shaft spinning freely, and to carry away a lot of the heat. The oil must be clean and it must have all the additives that keep it flowing freely. A bit of dirt and the bearing will be scratched, reducing the surface area. Some sludge building up and the oil wonít drain away fast enough and force its way through the seals into the engine, producing vast clouds of smoke. A breakdown of the additives that keep the oil forming a protective film at extreme temperatures, and the bearing will melt in the blink of an eye. So, clean, good quality oil is a must, and, simple things that they are, clean, good quality oil is all that turbo chargers ask. If they get it, theyíll go on more or less forever.

I mentioned that the manufacturers donít help with the TLC. Thatís because they are rather obsessive about minimising the disruption to our lives caused by taking the car to be serviced. 12,000 miles is a normal service interval these days, and some cars are intended to go for 20,000 miles before a technician lifts the bonnet and looks to see if thereís any damage. Now, 12,000 miles is half way round the world. Even if you average 50 mph it will take 600 hours of non-stop driving. In 600 hours, that little turbo shaft, red hot at one end, ice cold at the other, will have spun round about 72 million times. Thatís an awful lot of spinning before anyone looks in to see if everythingís OK. Apart from quite long service intervals, not every manufacturer recommends the use of flushing oil at an oil change. This is a shame because dirty oil starts to get thick and form a sludge, which builds up in important small oil passages Ė like the feed passages and drain holes for the turbo bearings. Sludging is even worse when oil gets very hot, as it does when it tries to cool a turbocharger. You end up with the engine equivalent of high cholesterol and clogged arteries.

There are lots of very long lived turbo chargers, and most of them have one thing in common. The engine oil and filter are changed religiously at no more than 6,000 miles and the oil system is flushed at every oil change. It takes half an hour and costs £20 - £30. So, be nice to your turbo, keep its arteries unclogged and its oil clean. In return, itíll blow sweetly for as long as you want.

04-24-2008, 12:49 PM
:thumbup: Nice Post. :)