How often should cars need an oil change?

DefaultM

I had my car serviced in June and had the full works done, which I'm sure included an oil change.
4 to 5 months later and the oil light has just come on. Ive done about 4000 miles?

Checked the dipstick and its well below minimum.

To me that says either he didn't change the oil like he said, or I've got a leak?

Fretwired

Is there an oil patch under your car?

guitarcookie1

Probably just used it. Some cars use more oil than others. 

boogieman

What sort of mileage is on the clock? Could be the engine is burning it....getting any blue smoke out of the exhaust? Is the oil relatively clean or is it black? That'd be an indication that it's been changed recently or not. 

randella

Some cars just use oil and are otherwise absolutely fine, mine certainly does. A litre every few thousand miles is well within spec. On the upside, it does mean you have cleaner oil in the engine if you're regularly topping it up...

DefaultM

90000 on the clock. No patch under the car.

https://i.imgur.com/dPZecMG.jpg

Sambostar

Modern overhead cam engines as much as possible with precisely the right grade and type of oil, along with oil filters as everything that is critical to the crank and valve timing runs off oil pressure.

Mk5 Transit 2.5Di Pushrod engine...about once every 400,000 miles.  Modern technology is so good eh...

Check for oil leaks, check around the oil filter and check for blow by for oil in your air filter and change the oil.  I wouldn't advise getting a thicker oil as it will probably knacker your modern engine.

Steffo

That looks like old oil to me...

DefaultM

Right so I'm thinking they didn't change it. Cheeky fuckers. I asked if they could do it asap because I had to have it back to pick my son up from school, so they probably just didn't bother.

randella

Steffo said:

That looks like old oil to me...

My car can turn new oil into sludge in about ten miles. After 4000 it'd certainly look like the pic above. 

randella

But yeah, it's entirely possible they mugged you off. Next time check the dipstick straight away, the new oil should be the colour of golden syrup. 

DefaultM

So I think the thing to do would be to go and get a litre of new oil, put half in, check the dipstick and then see what happens in the coming weeks?

randella

Sounds eminently sensible. You might need the whole litre if it's off the bottom of the dipstick - put a bit in at a time and keep checking, then see how you go on for a few miles. 

boogieman

DefaultM said:

So I think the thing to do would be to go and get a litre of new oil, put half in, check the dipstick and then see what happens in the coming weeks?

Yup. Top it up to max and keep an eye on it. 

DefaultM

I used an online checker which is saying I need castrol 0w-30 but I can only find 5w-40 in the local town. They both say they're for BMW, what's the difference?

Sambostar

http://www.driverstechnology.co.uk/oils.htm

Generally you can go a bit thicker after 50,000 miles than the manufacturer's prescription, but on modern engines I don't know if that is good advice to be honest..  Order it online, it'll be cheaper anyway.

strtdv

With 90k miles on the clock I'd expect it to burn a bit of oil, especially if you're doing short journeys in it.

My wife's car uses about half a litre every 10,000 miles.

Wazmeister

DefaultM said:

I had my car serviced in June and had the full works done, which I'm sure included an oil change.
4 to 5 months later and the oil light has just come on. Ive done about 4000 miles?

Checked the dipstick and its well below minimum.

To me that says either he didn't change the oil like he said, or I've got a leak?

More likely mate, your car has just used up the oil.

Ive got a BMW 320d Convertible and that goes through a fair bit...

DefaultM

My only thing is that I got the car in June 2015 and drove it for a full year without needing any oil, and the service book shows it didn't have the oil changed in the year before that either. Only did 8000 miles, got it serviced and it says full oil change. Drove for a few months and suddenly it's been used.

Don't get me wrong, if that's normal then I'm happy because it means I didn't get screwed over and the car doesn't have a fault. Just seems odd.

paul_c2

DefaultM said:

Right so I'm thinking they didn't change it. Cheeky fuckers. I asked if they could do it asap because I had to have it back to pick my son up from school, so they probably just didn't bother.

5 months on, you can't tell if they've changed it or not from the colour or the level. Its your responsibility to check the oil level, although many modern cars now have a level sensor. (Some) modern cars go through oil at a rate higher than you'd think, so its worth keeping on top of it and routinely checking. The consequences of running out of oil are very expensive, compared to topping it up.

I dare say, for the age and spec of car, the oil specification isn't simply "0W30 synthetic" or whatever. There will be a BMW quality standard over & above synthetic oil. There is a lot of debate over what it means and whether its needed but I'd not be cutting corners here. So, worth doing some proper research or even going to the BMW dealer for the oil (they may be the cheapest).

tone1

Just bear in mind most modern cars have an oil quality warning system. Especially diesels with DPF's. The extra fuel used to regenerate the DPF usually bore washes and waters down the oil quality and raises the oil level on the dipstick. So oil level looks good but in reality it's not good for the engine