Be Excellent To Each Other

It might not even have a dipstick. My BMW doesn't as far as I can see. Modern engines probably reply on a whole host of sensors to prevent them damaging themselves anyway.

https://www.amazon.co.uk/Carlube-Xcg500 ... 595&sr=8-5

Put that shit on everything you do up in some way. I swear my Tomcat is 90% Coppercoat.

The Porsche has an oil pressure gauge, which I (anally) have displayed at all times and watch like a hawk - this is very different from just a simple pressure switch/idiot light (it has them *as well*).

Hnnnngh, must resist…

Something like this happened to my dad once. The good news was, he discovered the issue before it wrecked the engine. The bad news was, he discovered it because the fountain of oil worked its way out of the engine bay and coated over the font brake discs, so when he brushed them to slow down in motorway traffic nothing happened... He ended up doing an emergency stop with the rear brakes only and spun the car in the process. (Everyone was fine.)

Crikey

Heathy has every confidence in Germanic automotive sensors.

Ouch, that's nasty. Easily done, too.

Years ago, some numpty from Kwik Fit left the oil filler off Mrs C's old Fiesta (HCS "Kent"-derived 1.3) engine, so consequently it coughed and splattered oil all over the engine exhaust manifold for a week, making her feel as sick as a dog.

"Hello, is that Audi UK?"
"Yes, how can we help?"
"I have an out of warranty claim for a complete seized and written off engine. I'd like £10,000 please."
"I'm sorry to hear that sir, how did this happen?"
"The engine oil was low, but I didn't appreciate the oil pressure sensor was haunted."
"Er, I'm sorry, what was that again?"
"The oil pressure sensor was haunted. An internet forum cohort told me this is the correct technical term."

/click

"Hello?"

Genuine question but is the gauge there just as an option for the benefit of people who like such things? Surely the car will take care of itself and tell you if the oil situation needed attention in good time.

I think the rationale is that the more highly stressed the engine, the more likely the need to monitor engine oil pressure. (I agree with this personally; the thing regularly gets ranted to 8,000 RPM and I ask a lot of it - and I don't fancy the £30,000 bill to replace the engine. Although an S4 or whatever it is is less highly strung, it's still a performance engine that's very expensive to replace)

Well yes but that's the sort of thing that computers are much better at than humans. Surely rather than having you look at a gauge it could just say "woah there pal" if something was edging towards a red zone?

As long as the sensor worked.

8000 revs is pretty good I guess. I mean it's not 9000, but y'know. Pretty sweet.

If the oil pressure sensor doesn't work, the dashboard gauge is gone too.

I suppose I'm drawing a distinction between a simple low oil pressure light and constantly monitoring oil pressure/trends and topping up all the time, by an extremely anal petrolhead. But I do see your side of the argument.

If there was a sudden, catastrophic loss of oil pressure, the computers/lights would kick in anyway. But what I'm talking about is running the engine *chronically* (not acutely) low on oil for possibly long periods, before the actual light flicks on.

Hey, it's his car/money though, each to his own.

My engine management light has been on for 10 months.

Sounds like a banshee; the hollow, naturally aspirated flat-six wail is like no other (and now, sadly, largely a matter for history).

The downside, though, is relative lack of performance - "only" 325 bhp for a 3.4 litre six (my son in law's chipped 2-litre turbo AMG Merc pumps out 400 bhp plus, with little over half the engine size), and a lot less torque. For me, though, character, noise, upper rev range and throttle response count for a lot, but I am stupidly old school.

The GT3 revs to over 9000RPM!

Depends how it fails - I might be gummed open.

Moral: Check the dipstick.

Why wouldn't the light be calibrated to flick on at an oil pressure level that's lower than normal but still high enough to not yet be causing damage?

Also, you're assuming the low pressure light is a binary thing where pressure below some value = light on. I don't think that's a safe assumption, particularly on a £70k Porsche -- let alone a £95k one. I suspect it's the ECU that decides when to flash that light, based on data coming from the same oil pressure gauge you're monitoring by eye. That could be using all sorts of data about the engine's condition and your driving habits to set the state of the warning light. Christ, given the software complexity of modern cars, I could believe there's a machine learning algorithm in there.

In this case though, the dipstick is behind the wheel.

It doesn't have a dipstick, the car is not supplied with one, and Audi don't make them, Audi's official position is it's not required.

It's not a 'low oil warning' light, (or an 'idiot' light as you so kindly refer to it), it's an advisory that the oil level is one litre below maximum capacity, and that the driver should add one litre of oil (but no more) at the next opportunity. (The message on the screen explicitly states that it is safe to continue driving normally.)

It is possible to buy third-party dipsticks (Audi don't make one that you can buy), and some people go down that route, but by all accounts the sensor as fitted is (a) reliable and (b) flags itself up as defective on the very rare occasions when it fails.

Also, you can read the oil level at any time using the MMI system in the car, and it'll show you a graphic of a bar on a scale of 0-100% (where 0% is one litre below max, and 100% is max). In old parlance, it shows the equivalent of MIN and MAX on a traditional dipstick.

The oil capacity of the engine is 6.2 litres, so I'm currently running with 5.2 litres, hardly into mechanical damage territory.

That could be true, Doc. When I think oil warning light, I think of a simple pressure switch (crude binary transducer) - but that's probably 1970s tech (lol), and I'm likely stupidly out of date?

Notwithstanding, though, I would *still* recommend regularly checking engine oil level yourself, by whatever means provided (manual dipstick or specific oil pressure test through the car's menus), especially on higher performance cars. But, this is simply my opinion.

@Hearthly

"Idiot light" is a well-known, oft-used term, don't take it personally as no offence was intended.

https://en.wikipedia.org/wiki/Idiot_light

As for the rest of the stuff - fine, fine, fill yer boots mate. Just don't say I didn't warn you.

Surely modern cars rely on loads of sensors, though. Aren't oil pressure gauges and dipsticks a bit of a throwback to make people who are used to such things feel better?

Suppose you wanted to do away with them then wouldn't you just make it so that an unchanging value is also an error?

They are, but they're often not reliable.

In the case of the Mazda, it thought it was fine, but it wasn't. Mazda knew this could be the case, so still state you should check the oil level every week.

It's been that way for some time, hence the saying that "It's not a 'warning' light, it's a £5,000 'idiot' light".

Basically; if the light's on, it might already be too late.

[edit]I totally agree that it shouldn't be this way, and maybe modern cars are better. Maybe not, though.

@cavey

o/

\o

Just passed the 110k mark in my modern classic Mk1 Leon.

I knew i wasn't dreaming.

That's incredible - Jap engines are just unreal.
If you tried that kind of caper on the Harley - despite making a fraction of the specific power output and redlining at a mere 5500RPM, it would probably implode on you, not least 'cause it's air cooled (as much as I dearly love Hogs)

I think the redline would be c13k rpm

On a Kwak ZX-6R?
Yeah probably, certainly there or thereabouts.

Note they had a litre of oil in though, they weren't empty. I suspect they wouldn't last as long if they were

Also coolant doesn't boil at 100 (or 120)degC, unless you're actually using water as coolant.

I'd imagine most of the damage was done running it hot.

Still, good little engine.

[edit]Oh, they only ran it for two minutes with not much oil

Talk to me on the motorbike thread!

Well at the end of the day I'm looking after the oil/oil level as per Audi's recommendation and what it says to do in the handbook. Assuming its consumption of oil is consistent you could make a case for adding 500ml every 750 miles rather than 1 litre every 1500 miles, but considering I do the best part of 1000 miles per month that sounds like far too much of a faff.

I'm comfortable knowing that the car will slowly move from 6.2 litres of oil to 5.2 litres of oil over the space of 1500 miles, at which point I'll top it up again.

Ha - I remember that from a mag my older brother read. Fast Bikes? Something like that.

Really? That's a lot of oil.

What was is about?

Yer mam, among others.

Very good.

So you can post some things straight away then?

A friend (of a friend really) had an RS4 and when the low oil warning came on it would restrict the power - I could see the message on the dash. It also set the sat nav with directions to an audi dealership, it seemed like it did that every time the car started, he said it was pretty annoying.

Also on oil (and coolant) I ran the big Falcon for ages without water, and possibly oil too, but I really wan't driving it far each day. The focus was running a bit funny so I checked the oil and it didn't seem like there was much (if any) in there and the residue on the dipstick was quite thick, not smooth and 'oily'. I'm not really too bothered though as I'll probably just run the focus until it shits itself and then scrap it. The engine management light sometimes comes on for a couple of days, then goes away for a couple.

Don't confuse oil pressure and oil level. Level doesn't really matter nowadays unless it's super low and you're putting Gs into the car through cornering or whatever. The second you get low pressure you get damage, having said that my old scimitar used to drink oil and every couple months under hard acceleration the oil light would flicker and that was my signal to give it a drink. Never had to change the oil as it was basically renewed every 6 months anyway, just swap the filter occasionally. What I liked about the oil light on that car is it was like a headlamp when it came on, attention grabbing as fuck.
Personal choice for any cars I put together is mechanical oil pressure gauge on capillary pipe, electric oil temp gauge and a bright oil pressure light on a pressure switch with a buzzer. The buzzer is oc when the engines off by way of a voltage sensitive relay. And a nice ping noise when you open the door with the side lights on.

I got a bug eye Corolla for free a while back and limped it through an MOT, hadn't run for a year but I've never checked the oil or coolant or spent a penny more than I had to for MOT, it refuses to die. In fact, maybe this would make a good next car for Mali...

So in summary my car's handbook, the S4 owner community, and indeed Audi's official advice as to how to monitor and maintain the oil level all turn out to be correct, and gradually running down to 5.2 litres of oil from 6.2 litres won't actually cause it to shit its own engine out the exhausts?

Good to know

Glad you asked?