Back in the 80's turbo cars like the Metro and Renualt 5 were fragile on a good day, add a poorly designed turbo and you were asking for trouble. Renault used to fit a fan under the bonnet that blew on the turbo after the engine was turned off. Most owners never spotted the fan did not work and eventually turbo failure loomed large.

The fan was used to stop fuel vaporisation in the carburettor - the heat from the engine and turbo would make the car difficult to start otherwise.

Regular turbo failures are alive and kicking on anything from BMW Diesels to MAN lorries, and lots of other makes and types too, and thats without throwing stop start faff into the mix for a thimbleful of fuel saving.

The new thinking might be oils are now fantastic, and apparently, so i read and am told, tolerances are better now than when a bloke in a smock rattled engine castings off his lathe after another rather muckier geezer fettled them...that'll be why some German engines are still throwing con rods and lunching their timing chains then?

Me, i still do things the old way, warming up and cooling down and very regular servicing, and i'll carry on doing so for the rest of me days, against all the advice from people who want to sell (or rather lease) me new cars or new turbos fed by gucci oils that last forever, or till the warranty expires.

Edited by gordonbennet on 11/07/2014 at 20:30

Unless you drive like an idiot, the turbo is unlikely to be near its maximum operating temperature so the thermal capacity of the oil is likely to be able to absorb the heat. Secondly, many turbos are now water cooled with an electric pump which operates even when the ignition is off. Thirdly, even at motorway speeds, the engine is not stressed - most cars can drive at well over 100 mph so at 70 mph they are probably operating at 50% max power.

Edited by Brit_in_Germany on 11/07/2014 at 21:08

Regardless of how hot the turbo is, The Shaft, Turbine and compressor will still be spinning at some speed when the oil feed stops due to no pressure.

That was my point. And as another poster mentioned running into slip road hold ups and come to think of it motorway tail backs, over a period of a year must take its toll on the turbo when the oil feed is cut off.

I assume as downsizing of engines continues, the turbos will be working harder, more of the time too.

The 140 PS engine in my Seat Leon does not need to work hard unless you are a total muppet. To keep up with normal traffic the engine is certainly not working hard. To overtake slower traffic you rarely have to floor the throttle or even drop down more than one gear, a gentle squeeze sees you past.

Lets be honest, 2500 rpm at 70 mph is not stressing anything. My first "decent" car was an Hilman Avenger 1600, at 70 mph it was doing 4400 rpm. When I moved up to a 2 litre Cortina (for a very short time) it was doing about 3800 rpm at 70 mph. Both those cars were populat with reps at the time ans in most cases spent nearly all their time on the motorway, probably at speeds over 70 mph. The engines lasted 100,000 miles in most cases but they were certainly more streesed and shirt lived than todays engines.

As for old type oils being better than modern oils comments like that continue to stun me. Modern synthetics are way better than old mineral oils but all modern oils lack ZDDP (ZincDialkylDithiophosphate) for one very good reason, it kills catalysts, even modern mineral oils lack ZDDP. For classics you can buy ZDDP additives but some companies sell modern synthetics etc that contain the correct amount of ZDDP for classics.