1961 Holden EK Pricing and Specs

You were on a pretty good bet that the problem was a case of warped brake rotors, but it seems new rotors have not fixed the problem. In which case, you need to start looking deeper into the suspension and front end of the car. There could be a worn bush or ball-joint, or perhaps something in the steering needs tightening or replacing. A slightly bent stub axle could also cause this. Make a note of whether it happens in corners (left or right) under light or heavy braking or even when accelerating. This information will help a mechanic diagnose the problem accurately.

But don’t ignore this as the problem will only get worse as whatever is worn becomes more worn. Eventually, you’ll have a car that shudders all the time and is unsafe to drive.

Many engines lose rpm when they are sitting at a hot idle. The problem could be with the fuel or ignition systems, but could also be a stepper motor that either needs to be replaced or reset (to re-establish the correct idle speed).

The oil light will be flickering because the sensor is telling the computer that there’s not enough oil pressure being generated to lubricate the engine properly. In turn, that’s because hot oil is thinner than thick oil (which means less oil pressure) and the amount of oil pressure generated is directly linked to how fast the engine is running. Hot (thin) oil plus a slow idle, means a dangerous fall in oil pressure.

If the oil pressure light goes out when you rev the engine a little, it will probably be okay, but don’t drive it like that for too long. Once the idle speed is reset, the oil light should not flicker on again. If it does, change the engine oil to a thicker (higher viscosity) specification.

There could be a complex, electronic, fuel-supply or engine-management reason for this, and if that's the case, having the vehicle scanned would be a good place to start. Or, it could be a case of human behaviour that is skewing your fuel economy figures.

By which, I mean that when you got the car brand-new, you gave it the kid-gloves treatment, understanding that the brand-new engine needed to be run in and would appreciate a slightly easier start to life. Then, as the novelty wore off and the vehicle began to earn its living, you subconsciously grew a heavier right foot. And it is this that's seen the fuel consumption creep up.

Failing that, you might have an on-board computer that has been silently recalibrating itself, perhaps in conjunction with software updates at the dealership which you may, or may not have, been made aware by the dealer. To be perfectly honest, I'd find 6.4-litre per 100km average on a Colorado borderline unbelievable, and the sort of economy only a dedicated fuel-saving driver could even get close to. Ten litres per 100km, meanw