Service rating of turbos

No Idea, but you'd have to drive like a complete and utter tw*t to use a petrol car's turbo to it's full capacity all the time on the road, so it could be true...:-)

Mike

Service ratings don't really work in the same way in cars. The vast majority of cars are built with a certain life (mileage) expectancy. Say the engine is expected to last x00,000 miles - where x is anything between 1 and 5. Any other major non-wear components are engineered to last about the same amount of time - given average driving conditions.

Interesting you should mention turbos, because they are an exception. The simplicity of a car turbo means that it has only two failure modes - eroded turbine/compressor blades and worn shaft bearing. This means that as long as the incoming air stream is clean (good quality, clean air filter with no air leaks anywhere else) and the supply of oil through the bearing is of adequate quality, flow rate and temperature, the turbo will last almost indefinitely! Sure it will eventually fail due to metal fatigue, but this will be after millions of miles, not hundreds of thousands.

Not true for the turbos that Saab uses, it's not unusual to get many hundreds of thousands of miles out of the original turbo without servicing. Can't speak to other brands of cars, they may not be as serious about it.

Turbo failures in Saab cars are very much the exception rather than the rule.

Dave Hinz

definately, i am running on my first turbo, car has 280.000km, just showing slight cracks in the casing, no play on the shaft or shattered blades... also what do you mean by full capacity? full pressure? you sure wont be running anywhere near that with a stock chip, even tuned cars just put out something around 1.5-1.8 bar of pressure... the turbo can handle it..

I wasn't thinking expressly about Saab turbos. I've read that some light pickups come with a warning about the turbo not be rated for extended use such as towing a heavy trailer up long grades.

They could mean that the cooling and/or lubrication systems are not adequate for long runs at high boost. This is definitely not the case with Saabs.

Generally speaking, an LPT is a standard turbo with smaller impellors. Nothing else is different (other than the ECU controlling it). The normal failure for a turbo is bearing failure. This happens prematurely when the heat of the turbo bakes the bearings. Most serious turbo installations have coolant lines running to cool them. They all have oil lines for the bearings. If you maintain your cooling system (flush and change every two years) and change the oil on a regular basis, the turbo can last a very long time. Synthetic oil helps, not only due to better lubrication, but because it runs at a lower temperature, too (averages 15°F cooler). Heat is the enemy.

The local Saab Service Manager says he's seen quite a few coked turbos "cleaned" by introduction of synthetic oil - eliminating the need for replacement or rebuild.

FWIW, Bob

Define coked? The off bit of soot is going to be moved by any oil, fresh or otherwise (to a point). Wear within the Turbo's bearings isn't going to be reversed by switching to synthetic.

Matt

Quite - I can't see how a turbo bearing can be coked. They always (all the ones I've taken apart) have a light brown glaze, but certainly not 'coked' in the sense you'd apply it to a cyl head.

FWIW, I don't run synth, and I don't have any problems, even on my non-water cooled 16T. I've put over 60k miles on that car so far. I use a semi-synth Total oil which my motor factor keep in bulk. It works very well, and is about £8/5 litres. It also keeps my seals from leaking, which synths haven't done in the past.

I use Mobil 1 0w/40 in the T16, but then thats not exactly an everyday car and when it does run regularaly see's 6500rpm repeatedly and 1.6bar for mins at a time, oil temp of

90 - 105degrees is common on a warm day. Don't really have a problem with seals dribbling as the engines apart so much most gaskets have 5K miles use ;-)

The 900i gets whatevers kicking about in the garage. Boggo standard Mobil

10W/40 semi at the moment IIRC.

Matt

well, synths dont break seals, they just leak through seals that are broken and have swollen up/closed up again because of the mineral oil... certainly i wouldnt switch a car to synth after it has run more than something like 80.000 miles on mineral oil...

Oh I know that - but that's why on an old car that spent half it's life running mineral oil switching to synth is a bad idea.