There are a couple of possibilities here. The first is that you have a genuine problem with the transmission and if so, that needs to be electronically scanned (as a first step) to see what’s going on inside the gearbox. Since this seems like new behaviour, this is probably the case, but until the transmission has been interrogated, you won’t know what’s causing the vehicle to limit access to some of its gears.

However, if it’s a vehicle you’ve only just bought and the idea of skipping gears seems odd, bear in mind that this is perfectly normal for modern cars with lots of different ratios. It’s pretty common, for instance, for a modern automatic to jump from first to third, or third to fifth if it doesn’t actually need the extra performance that selecting each gear in turn offers.

Another check you can perform to perhaps confirm this is to manually select each gear as you accelerate up to highway speeds. If all the gears engage one after the other manually, then the problem is possibly not a mechanical one within the transmission and maybe a selection issue instead.

Any time a mechanic sees an illogical pattern of faults like these all at once, their suspicions are always drawn to the body computer. This computer controls all the functions you’ve mentioned as well as hundred more, and when it goes on the fritz (as computers are wont to do) you can suddenly get all sorts of weird behaviour, just like you’re reporting.

Take the car to an auto electrician who might be able to make sense of what could be a complex wiring issue. But the smart money says body computer every time. These can be replaced by a new computer, second-hand ones from a wreck and sometimes even fixed by very clever people. If the auto electrician can’t offer any advice, get online and see what help is out there.

Whether this is a problem or not all depends on how much oil you consider to be too much. There’s an old school of thought that says an internal combustion engine shouldn’t use any engine oil. That’s not actually accurate. A small amount of oil is scraped past the engine’s piston rings and burned every time the engine turns over (which it typically does at anything up to 7000 times a minute). So some reduction in the level of oil in the sump is pretty much inevitable.

Some modern engines also use low friction internal components to make them more fuel efficient and, in some makes and models, this has had the effect of increasing oil consumption. Again, this is perfectly normal and the pay-off is you use less fuel.

Rather than just a drop in oil level, you should be looking at the drop compared with the kilometres you’ve covered. A car that consumes, say, a litre of oil (or even two litres) between its 10,000km oil changes is not a problem at all. Some manufacturers even say a greater level of oil consumption than this is still within acceptable tolerances. Anything up to 1.5 litres per 1000km can still be within a car-maker’s specification.

What you’re really looking for when checking your oil level is any change in the engine’s oil sipping habits. A sudden increase in the amount it normally consumes is when you need to start looking more closely.

That said, if the car is using too much oil, then it’s either being burned in the engine (suggesting worn engine parts) or it’s escaping the engine somehow (otherwise known as a good old-fashioned oil leak). A big patch of oil on the ground where the car is normally parked means you need to go hunting for a leak.