Ask the Guide

When an engine (petrol or diesel) inhales water through its air-intake system, it's never usually a good outcome. Because water is – as is any liquid – non-compressible, the engine's pistons will try to achieve that but, in the process, the engine will lock up and all sorts of internal carnage can ensue.

If you're lucky, the damage will be fixable but can still involve bent con-rods, broken pistons and bent valves. If the lock up was more severe, there's a chance that the engine block could be cracked or a con-rod has broken and punched a hole through the crankcase. Sometimes the force of the lock up is sufficient to smash the main bearing caps and throw the crankshaft out of place. In any of those latter cases, the whole engine would be considered a total loss.

But even if you've gotten away with a bent con-rod or two, you'd still need to rebuild the entire engine and, in the context of a 2004 Rodeo ute, you might find you're spending more money than the vehicle is actually worth.

A potentially better idea would be to find a good, tested second-hand engine from a wrecking yard or any other sort of damaged Rodeo and do a relatively simple heart transplant.

The first thing to figure out is which version of the 2012 Q5 you have. See, in that year, Audi updated the Q5 and, in the interests of fuel saving, changed from a conventional hydraulic power-steering system to an electro-mechanical one. Each system has the potential to give problems, but for very different reasons. The change came in late 2012 (December) so your car is probably the earlier one, but a check of the build-plate will tell all.

In the case of normal power-steering, low fluid can cause the problems you've noted and is also likely to make the power steering noisy when you turn the wheel. In the electro-mechanical system, the fault could be with the electric motor that powers the steering assistance. In both cases, wear in the actual steering rack can cause the same symptoms. Either way, it needs to be checked by a specialist, as a car's steering is obviously a crucial system.

But before you do that, have the car's wheel alignment checked at a tyre shop. A car that is out of whack can sometimes exhibit very strange steering characteristics. And what about the absolute basics? When did you last check your tyre pressures? Low tyre pressure can also make the steering heavier than it should be. And it doesn't matter that you haven't had a flat tyre for years; tyres lose about one psi per month, just sitting in the driveway. That's why they need to be pressure-checked every few weeks.

The recommendation from the trade is to use a fully synthetic 0W20 or 5W30 grade oil. As the grade suggests, this is quite thin oil, but it allows the oil to flow easily when it's cold and, therefore, reduce wear. Modern engines like the Subaru's have many intricate, tiny oilways associated with the variable vale timing mechanisms, so a thinner, easier-flowing oil is often what's needed.

The flip-side is that modern engines with low-tension piston rings (for better fuel economy) are apt to drink a little oil between oil-changes. So you need to keep an eye on the oil level on the dipstick to avoid running the engine low on oil. This isn't a Subaru-specific thing, but applies to many modern engine designs. What you'll spend on oil will be more than offset by the fuel savings a modern engine can provide.

This is an example of why you really shouldn't ignore warning lights as they flash up on your dashboard. In the case of the dual-clutch Audi transmission you have, the warning light indicates that there's a problem inside the transmission (often that the clutch-packs have overheated). Continuing to use the vehicle normally is not recommended as the transmission requires attention to prevent this overheating occurring again and causing permanent damage to the unit.

Audi certainly knew it had a problem with these transmissions back in the day and often the root cause was traced back to the mechatronics unit (the brain that controls the gearbox's clutches and selectors) and in many cases these units were replaced.

However, the chances of Audi attending to your problem now after many years of ignoring the warnings seems a bit remote. You might be lucky and discover that the warning is something as simple as a faulty sensor, but if there's damage inside the transmission, this won't be a cheap fix. Have the vehicle scanned and see what the transmission has been trying to tell you all these years. By the way, Audi's response at the time was in the form of a service bulletin, not a recall.