You’re right that error code P0171 on this car equals an engine that is running too lean. That is, There’s either not enough fuel or too much air in the cylinders. On this engine, many owners have found that the PCV valve can fail, but also that the rocker cover itself can contribute to vacuum leaks. If you can hear air hissing anywhere, then a vacuum leak somewhere around the engine is a pretty good bet.

But let’s not forget that a lean mixture can be caused by not enough fuel, as well as too much air. In which case a check of the fuel filter, fuel pump delivery volume and pressure are warranted. You can also get a lean error code from a faulty or dirty MAF sensor in the engine’s intake system.

The gasket in question is probably the head gasket and when this fails, it can allow the engine oil and coolant to mix, which is why you’re seeing oil in the coolant expansion tank. If you check the engine’s oil dipstick, you may find that coolant has found its way into the sump, mixing with the oil as well, giving the latter a milky quality rather than appearing clear and clean.

This would have been a potential warranty claim back when the car was new, but at 11 years of age – even with your low mileage – it would be a miracle if Holden agreed to fix it as part of a warranty job.

This is a slightly tricky one because while both the SRi and SRi-V were fitted with the same engine, this point in time marked a change in specification. Around March of 2013, Holden switched the SRi and SRi-V engines form the 1.4-litre unit to the 1.6-litre unit. The automatic transmission was updated with a sport-shift mode and predictive down shifting, although physically the automatic and manual transmissions were carried over to the 1.6-litre version.

On the surface, this sounds like a viable swap, but you could run into wiring and computer problems in trying to make what was a 1.4-litre car `talk’ to the 1.6-litre engine. The 1.6-litre engine also used direct fuel injection, so you’d need the entire engine management system and computer to go with the swap. There may also be physical differences in things like airbox design and exhaust locations, too, so you need to drag out the tape measure and make an assessment based on measurements and facts. However, if your 2013 car was one from later in that year, it will already have the 1.6-litre engine and the swap to an engine from a 2014 car should be pretty straightforward.