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| Modern oils in red hot turbo's need only a slow drive to cool. |
Q:
THE new Alfa Romeo 4C uses an automatic cool-down system to protect its
turbocharger — much like the Tata Telcoline bakkie.
But I’ve learned that
driving a car with synthetic oil slowly for the last kilometre before switching
off gives the oil enough time to cool down.
This presumably prevents the “thermal stress” Alfa
says will happen to “very hot oil” if the engine suddenly stops pumping it
through the turbo.
Must we keep our turbos idling after a normal drive, or not?
JENS Denks at Denks
Motors answers: Alfa always tries to be a step ahead, but instead they
complicate things — like by running a separate earth wire for every live wire
that traversed the car instead of using the body as an earth and now this
after-run electric pump in the 4C.
The pump is automatically controlled by the
ECU and keeps the oil circulating through the turbocharger until it has cooled
sufficiently.
A much simpler, proven system is to use a spring loaded vacuum
cylinder to suck oil in as the engine starts up and then to discharges it slowly
as the engine is switched off. Similar systems have been available in SA for
donkeys years and are typically mounted in a relatively cool place in the
engine, like the tappet cover.
Drivers of modern cars do not need a lengthy idle
at start up or before switch off — this habit just wastes fuel at about R14 a
litre.
As long as you drive moderately when the engine is cold or before
you’re about to switch it off, you will not break things. Bear in mind that
internal combustion engines are extremely inefficient at low speeds and idle,
which leads to fouling in the engine systems, including the oil.
When the engine is well-maintained and has reached operating
temperature, just drive it with verve.
HOW can the dealership justify offering me a trade-in of only one-fifty and then put my car on the floor for two hundred big ones?
GORDON Hall of the
car-review website scarletpumpkin.com answers:
Without being apologists for the dealer, that two hundred big ones
only include R17 small ones for the dealer. Let’s look at what happened to your
car before it was sold to its proud new owner at R200 000.
The first consideration is that the dealership has to pay 14% VAT,
which means the dealer got a nett sum of R175 439. You also believed your car
only needed a decent wash before it could be sold.
The dealer instead had to fix
a few dings and scrapes, clean the engine and interior, buy two new tyres, and
get a roadworthy certificate, totalling R10 000.
Add that to the R150 000 he gave you against your new car, and the
dealer is now R160 000 out of pocket. He also has to feed and clothe his kids
and pay salaries, so he adds 10%, bringing his net selling price before VAT to
R176 000.
But he priced it at R175 439 to make the price a round R200 000 —
which is as close as anything to what you might have got for it on the Internet,
if you were willing to take the time, as well as run the risk of dealings with
hoodlums or con-artists.
