Cheap vs expensive oil

jsmoke · 21 Jul 2020 at 12:31

Not a troll thread!!

I came across this post and it got me thinking.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=1573243

Now I've seen 5L of oil for £15 and I'm sure you could go up to £50+ for "expensive oil".

Now in an engine as far as I know, the only parts really affected will be the rocker arms and lifters and the main bearings, as everything else like crank, cams and pistons shouldn't be affected buy the price of oil you use.

Your also changing your oil every 10k miles or so, so overall I agree that there shouldn't be any difference in engine longevity or mpg with regard to the oil you use. You might lengthen the main bearings or lifters though.

Maybe if you want to get 500,000+ miles there may be a factor or you may get a few extra mpg but overall there's no data to suggest that more expensive oil will lengthen the life of your engine, it may however give you a slight efficiency boost.

Opinions?

SonicSW20 · 21 Jul 2020 at 12:37

There's no one answer that fits all - depends on the car, depends on the application. Oil choice for a 90's turbocharged performance car that sees use on track days is a very different requirement to a modern 1.xL turbocharged commuter box for example.

InvaderGIR · 21 Jul 2020 at 12:51

@Simon is your man for oil iirc.

As far as I'm aware (and to simplify things) it's all down to the additives that are in the oil, cheaper oils having less in them etc.

Along with bearings you also have the chance of seals reacting to things I think.

Some older engines run and last better on mineral rather than synthetic oils too, I don't know if that's down to the metals used in them or what though.

E: Conversely, I think modern engines run better with synthetic oils over mineral ones?

SonicSW20 · 21 Jul 2020 at 12:55

InvaderGIR said:
Some older engines run and last better on mineral rather than synthetic oils too, I don't know if that's down to the metals used in them or what though.

That one is a bit of a myth, stemming from early synthetics not being available in suitable specs for older engines. If it meets the spec for viscosity and additives, synthetic is fine in any engine.

joey1211 · 21 Jul 2020 at 12:57

How much of the extra cost would be down to marketing?

jsmoke · 21 Jul 2020 at 12:58

I can see if you live in Antarctica then you'd want a thicker oil, or higher viscosity oil, other than that I can't see how a cheap thin oil as long as your changing it on recommend intervals isn't the best economic and performance option.

InvaderGIR · 21 Jul 2020 at 12:59

SonicSW20 said:
That one is a bit of a myth, stemming from early synthetics not being available in suitable specs for older engines. If it meets the spec for viscosity and additives, synthetic is fine in any engine.

I did wonder tbh. Having not run side-by-side comparisons between them. I've tended to use synth for all my vehicles anyway including 30 year old engines and had no adverse affects.

jsmoke · 21 Jul 2020 at 13:01

The other thing, it would be more beneficial to replace your oil pump at certain intervals than use an expensive oil.

Doobedoo · 21 Jul 2020 at 13:04

I use decent oil for my Skoda as it needs specific oil in a PD engine although it’s still reasonably priced.

Oil is a huge con as in the mark up they make selling it to joe public compared to selling it to garages in bulk. I saw a receipt once when I was in Halfords and they were paying somewhere in the region of £1 per litre so a huge mark up.

Armageus · 21 Jul 2020 at 13:10

It's worth bearing in mind that most modern Diesels do need specific oils, due to the DPF regeneration process, whereby a small amount of oil is burnt, and if a low-SAPS (Sulphated Ash, Phosphorous, Sulphur) oil isn't used this can lead to DPF blocking etc.

https://www.opieoils.co.uk/t-dpf-diesel-particulate-filters-explained.aspx

Simon · 21 Jul 2020 at 13:11

jsmoke said:
Not a troll thread!!

I came across this post and it got me thinking.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=1573243

Now I've seen 5L of oil for £15 and I'm sure you could go up to £50+ for "expensive oil".

Now in an engine as far as I know, the only parts really affected will be the rocker arms and lifters and the main bearings, as everything else like crank, cams and pistons shouldn't be affected buy the price of oil you use.

Your also changing your oil every 10k miles or so, so overall I agree that there shouldn't be any difference in engine longevity or mpg with regard to the oil you use. You might lengthen the main bearings or lifters though.

Maybe if you want to get 500,000+ miles there may be a factor or you may get a few extra mpg but overall there's no data to suggest that more expensive oil will lengthen the life of your engine, it may however give you a slight efficiency boost.

Opinions?

Oil is cheap vs an engine and the OEMs wouldn't spend millions developing tests and specifications if any old oil will do.

paradigm · 21 Jul 2020 at 13:17

jsmoke said:
I can see if you live in Antarctica then you'd want a thicker oil, or higher viscosity oil

Isn't that the opposite of what you'd want?

Firestar_3x · 21 Jul 2020 at 13:29

OP, Projectfarm on YouTube does some basic wear testing for different oils, go watch his channel.

Orionaut · 21 Jul 2020 at 13:31

Armageus said:
It's worth bearing in mind that most modern Diesels do need specific oils, due to the DPF regeneration process, whereby a small amount of oil is burnt, and if a low-SAPS (Sulphated Ash, Phosphorous, Sulphur) oil isn't used this can lead to DPF blocking etc.

https://www.opieoils.co.uk/t-dpf-diesel-particulate-filters-explained.aspx

To play devils advocate.

I have always wondered about this.

A Modern engine in good condition will use little or no oil between services.

If you are not actually burning any oil, how could what is in the oil damage an exhaust component?

By contrast. I would imagine that if one is burning oil in sufficient quantities that a DPF will be damaged by a non-DPF spec oil, then the soot/smoke from the oil burning would probably kill it in short order anyway. Even if you were using the correct spec oil.

Firestar_3x · 21 Jul 2020 at 13:39

Every engine will burn oil, the dipstick is an imprecise tool for measuring small use, therefore it comes down to the quantity of oil over what duration is needed to be burned before you damage the DPF.

stoofa · 21 Jul 2020 at 14:13

For my car I just make sure the top-ups I buy (and rarely use) meet the engine specification - which is VW 504/507, 5w-30 Fully Synthetic. My car is on Extended servicing, so can go 20k miles between a service.
In my mind it doesn't matter the brand, for it to meet these VW Specifications it has to be designed for use in my car and be good for those miles between changes.
I've topped up Shell, I've topped up Halfords own brand - so long as it meets those specifications I'm happy.

Mercenary Keyboard Warrior · 21 Jul 2020 at 14:14

paradigm said:
Isn't that the opposite of what you'd want?

Yes, hes got it the wrong way round basically, although the point in 10-30 etc is that it denotes the lower and top ranges.
Once things have been running a while they can still get to a reasonable heat. If you look at things like ice road trucks, they cover the grills as they don't need any airflow the engines never quite get upto temp as such.

I remember seeing a program on military tech being tested in extreme cold once and how it affected things like oil. Rubber becomes brittle etc

Mercenary Keyboard Warrior · 21 Jul 2020 at 14:21

Firestar_3x said:
Every engine will burn oil, the dipstick is an imprecise tool for measuring small use, therefore it comes down to the quantity of oil over what duration is needed to be burned before you damage the DPF.

True, having had new cars from Ford, Subaru, toyota, BMW, merc, audi and vauxhall every one has used some oil. All apart from the Audi woudl go to the service needing no top up. My audi uses I woudl estimate around 1 litre for 15k miles (around my usage dependent interval) so I need to fill up once or twice, or multiple small top ups per service interval. Clearly something Audi do uses a little oil. A few people claim theirs doesnt use any, a few claim it uses loads, so I suspect the oil usage is somehow usage dependent.
What I find odd is that the oil remains very clear so its not getting contaminated, but no doubt it uses a little.

Terminal_Boy · 21 Jul 2020 at 14:29

paradigm said:
Isn't that the opposite of what you'd want?

Yup. Thin oil for cold climates, thicker for hot.

jsmoke · 21 Jul 2020 at 14:36

Terminal_Boy said:
Yup. Thin oil for cold climates, thicker for hot.

Wrong way around, I assumed thin would freeze easier.