Oil changes... What are your thoughts?

[Butcher]

Get a good mechanic, do what they say

I tend to consume cars rather than sell them on, and have had cars from reasonably low mileage where I run them on fully synthetic oil but as they get older you switch to something like magnatec because a thin oil burns off too fast. So no general rule really.

3000 miles for an oil change though? Get better oil, that is nuts.

Limit for how long you should wait depends on how the car is used. My low mileage Alfa will probably have done 8K miles when the yearly service comes up and the service indicator probably wouldn't come up for another 10K as I hardly get to bounce the rev counter off the limiter, but at MOT time I will get a service done with oil change anyway as fluids can be a bit manky after a year. I think the official schedule for my car is 18K miles or 18 months, but yearly isn't exactly a chore.

OTOH, if you have been on a track day then it is probably worth an oil change regardless of distance covered.

I used to work with someone who back in the 90's bought a brand new BMW 3 series and with his very long commute he drive it for three years just topping it up. I think it was his first MOT when he figured he should have the car serviced and the engine was running but in pretty bad shape, but thanks to his very long commute he had done something like 150K miles by then. That's another single data point, but shows that the world doesn't end at 12K miles.

Mine gets changed every 10k (which is about every 8 months), regardless of usage. I've checked it after track days and it's not in particularly worse shape than before. One thing I am considering is an oil cooler to help with on track oil temperatures (130C isn't great).

[DanceswithUnix]

I dunno,from what I gather its never on offer and he is a bargain hunter like me! Its a specific weird grade,and I am sure he would be quite happy to use cheaper stuff!!

Not something you want to ever skimp on by buying dodgy mineral oil.

Looks like *all* Castrol 4l oil is on offer at Halfords, but they don't have the Edge 10W60 that my wife's car uses in stock locally. Annoyingly that won't go in my turbo engine either, so should get another bottle for topping my car up. I would imagine turbo diesels are the common case these days.

[DanceswithUnix]

... but undergoes lots of stop start because of the Stop/Start system. When an egine stops turning, the oil pressure in the bearings that support the crank shaft is squished out... over and over. Same for the cam shafts.

I think there is a secondary electric oil pump in my car to deal with that. I presume for turbo bearings too (never had a turbo apart).

[Butcher]

Not something you want to ever skimp on by buying dodgy mineral oil.

Looks like *all* Castrol 4l oil is on offer at Halfords, but they don't have the Edge 10W60 that my wife's car uses in stock locally. Annoyingly that won't go in my turbo engine either, so should get another bottle for topping my car up. I would imagine turbo diesels are the common case these days.

Could be worse, they don't even sell 0W20 in larger than 1L bottles, and those are £20 a pop!

[Butcher]

I think there is a secondary electric oil pump in my car to deal with that. I presume for turbo bearings too (never had a turbo apart).

Is yours an Audi? I think they use a water cooled turbo, so there's no need for the turbo bearings to have a secondary oil pump. The water pump continues to run when the engine stops to help with turbo cooling.

[badass]

Yet another site (jalopnik)perpetuating the car club myth that 3000 mile changes are a good idea.

1. Americans use rubbish oil. I don't care how often Americans need to change their rubbish oil.
2. Regardless of what the car club consensus is on changing your oil every 3-4 engine revolutions, the number of 150,000 mile plus cars on the road that just have manufacturer recommended service intervals followed says they are fine.
3. Regardless of what complex explanations of what oil goes through people with knowledge of cars come up with to justify changing your oil every 30 seconds - see point 2. Engines using manufacturer recommended oils with manufacturer recommended intervals last.

However if you thrash your car to within an inch of its life on a regular basis, you will probably need to spend more on maintaining it. Including more regular oil changes.

My A3 2.0TFSi which was bought with less than 40,000 miles has now done 140,000 miles and engine wise has only had an issue with an injector(i.e. nothing to do with the oil). Probably because of the fact that it's lived off supermarket wee wee for the last 80,000 miles.

It had longlife services for the first 3 years as it did 20,000 plus miles per year for the first 2 years and then around 15,000 miles the next year. Since then its had regular 10,000 mile services. The vast majority of the car buying public will treat their cars the same. The longlife oils are funnily enough designed to last longer.

On the Manufacturer recommended oils, they don't say "any 0w30 is fine" or something similar. VW have a system like VW 504.00 - I have been using only that for both long life and regular servicing.

See here: https://www.carparts4less.co.uk/cp4l...IaAvyGEALw_wcB

The bottom bit is important:
Castrol EDGE 5W-30 LL is suitable for use in automobile, gasoline and diesel engines where the manufacturer recommends an ACEA C3 specification 5W-30 lubricant.
Castrol EDGE 5W-30 LL is approved for use in vehicles that require a lubricant meeting
VW 504 00 / 507 00,
Porsche C30
MB-Approval 229.31/229.51 5W-30

[kalniel]

I know my mates Skoda with a diesel engine needs very special stuff according to him,which is rarely on offer.

Chances are it's the same VW504/507 as almost all VAG engines, in which case Catrol Edge is certified and is frequently on offer, eg 4L for £25 at amazon:
https://www.amazon.co.uk/Castrol-EDG.../dp/B011KRAGH8

[CAT-THE-FIFTH]

Not something you want to ever skimp on by buying dodgy mineral oil.

Looks like *all* Castrol 4l oil is on offer at Halfords, but they don't have the Edge 10W60 that my wife's car uses in stock locally. Annoyingly that won't go in my turbo engine either, so should get another bottle for topping my car up. I would imagine turbo diesels are the common case these days.

Chances are it's the same VW504/507 as almost all VAG engines, in which case Catrol Edge is certified and is frequently on offer, eg 4L for £25 at amazon:
https://www.amazon.co.uk/Castrol-EDG.../dp/B011KRAGH8

All I know it was more expensive than say the stuff for some other diesels,but again I don't whether that made it expensive or "relatively" expensive!

[DanceswithUnix]

Is yours an Audi? I think they use a water cooled turbo, so there's no need for the turbo bearings to have a secondary oil pump. The water pump continues to run when the engine stops to help with turbo cooling.

Nope, an Alfa. Turns out some multiair engines have secondary pumps, they are water pumps, and mine isn't one of them. So I learnt something today, thanks again Google

[Xlucine]

Amazon is great for oil and filters. I tried to support my local motor factor, but it closed down anyway

Oil contains lots of stuff. Cool stuff.. like detergents and additives.. and bad stuff, like Suphur, Ash, Potassium (SAPs)

the chains of molecules need to stay together for the life of the oil. The sheering properties of an engine, (pulling the molecules apart for want of a better word), under both super hot temps, ice cold temperatures, while potentially having small amount sof combustion gases mixed into them, makes engine oil life HELL ON EARTH.

Imagine this - 1 engine with slight wear on one set of piston rings, meaning that a tiny tiny amount of exhaust gas is squished through the rings down into the sump on every ignition/expansion cycle of the engine

1 engine doesnt have that, but runs in freezing temperatures, gets super hot.. and every day splashes through puddles of ice water, cooling the sump over and over.

I cannot tell you what this does to the oil, but I am sure it's DIFFERENT for both. And not pretty.

Then another engine that revs to 7000rpm every day.. and another that ticks over in traffic ... but undergoes lots of stop start because of the Stop/Start system. When an egine stops turning, the oil pressure in the bearings that support the crank shaft is squished out... over and over. Same for the cam shafts.

and then a fourth engine that never gets warm. It turns on, drives 3 miles switches off.. and 7 hours later turns on drives three miles and turns off.

Cheap oil, ala American cars of old, where you could get the oil changed every 3750 miles or allegendly lose your warranty... had cheap oil. badly refined bulk rubbish. But it came free with a steak meal (yes.. American drive through oil service and dinner)

Mobil, a LOOOONG time ago cameout with Mobil1 and I ran it in my rally cars. It came out looking/feeling like brand new ...unlike the old 10w40 that was black after 3 events. Mobile tried and failed to hold the legal rights for "sysnthetic". It was never gonna stick.
But they did a great thing in my opinion, they got top grade oil to the masses. Bloody expenvie but very good.

Look up what spec you engine needs and stick to it. Dn't run fully synthetic 0w30 in a classic. Don't run 10w40 is a modern BMW.

ALWAYS change the filter with the oil
ALWAYS buy A QUALITY FILTER - the hydraulic pressure bearing into the centre of an oil filter can crush a weak filter core.

And dip it often

I'm not convinced on thermal cycling being bad for oil. At high temp you'll get the boltzmann distribution for the activation energy to oxidise it or whatever, but there's no mechanism for thermal fatigue like you'd get in a solid. Stop-start driving has its own set of challenges, but the temperature change for the oil isn't one of them.

I think there is a secondary electric oil pump in my car to deal with that. I presume for turbo bearings too (never had a turbo apart).

Unfortunately that doesn't work - you need the shaft to be spinning for a hydrodynamic bearing like that to work (as you're relying on the shear stress to pull the oil around the bearing). If it stops, even with oil pressure still supplied, it'll just settle to the bottom of the hole (or opposite the oil supply hole, if the oil pressure is high enough)

[joshwa]

Thanks for all the replies

So basically, to summarise:

Don't buy cheap oil.
Use the recommended oil for your car (whatever that may be: semi/synthetic 5/30 etc, and for some manufacturers also ensure the correct VW spec is followed).
Follow the manufacturers change policy*
America/Americans are wrong

So what I tend to do is annual services. Seems okay, as my mileage is lower than <10K a year.

* Even if that's "long-life" changes.

Which brings me to the next question(s) - how long have people driven on long-life before changing the oil?
And why do Diesel cars have oil that goes black within weeks of the oil being changed?

[Bagnaj97]

Just check the oil - if you notice its starting to change colour,change it even if its before the recommended time or mileage interval.

Oil in a diesel goes black pretty much the moment you turn the key.

I know my mates Skoda with a diesel engine needs very special stuff according to him,which is rarely on offer.

Oil meeting the VW507.00 spec - dunno what's in it, but it's not cheap!

[kalniel]

And why do Diesel cars have oil that goes black within weeks of the oil being changed?

Diesels produce a lot of carbon aka soot in the combustion process.

Oil meeting the VW507.00 spec - dunno what's in it, but it's not cheap!

Yeah it is, see my earlier link. It's about £20-25 for 4 litres of the stuff.

[rich835]

Change my oil and filter yearly regardless of mileage.

Yep, I have the same attitude, and I do 24K a year! My last car did me well for 200K before I got rid. I got a basic service once a year and that was it, never spent a bean on it apart from tyres, brake pads etc.

[Ttaskmaster]

All I know it was more expensive than say the stuff for some other diesels,but again I don't whether that made it expensive or "relatively" expensive!

It just needs to be the right VW number as specified in the Owners Manual, and the bottle should say on the back. My own Diesel Škoda takes VW 505 01 for fixed interval, 506 01 for variable, or simply 507 00 for long life. Pretty darn common.
If it's simply that it's never on discounted sale, he needs to look elsewhere or buy in bulk from a trade supplier.

[Butcher]

Which brings me to the next question(s) - how long have people driven on long-life before changing the oil?
And why do Diesel cars have oil that goes black within weeks of the oil being changed?

Back when I had cars that had the option of long-life, I never managed more than 10k miles. I ended up getting it switched to fixed interval since that's 10k miles anyway but cheaper (as the fixed interval oil is cheaper).