0W-20 oil or 5W-40 oil
Discussion
Hi, I m wanting to do an oil service on my own. And torn between which oil viscosity to use.
The manufacturer recommended 5W-40 oil for the pre facelift cars and then one year suddenly changed their recommendation to 0W-20.
Having gone down a rabbit hole on other forums. Some people claimed the manufacturer only did this to meet MPG fuel efficiency targets. And the thinner 0W-20 doesn t have any other benefit. Some even claimed the thinner oil can be detrimental for high mileage / highly stressed engines, as it offers less wear protection.
What do you think? Is this a wacky conspiracy theory and I should stick to the manufacturers recommendation of 0W-20? Or should I use the thicker 5W-40 instead, if I want to keep my car forever and run it into the ground? Thanks.
The cars a VW Golf. With the 2 litre EA888 engine. Around 60,000 miles.
The manufacturer recommended 5W-40 oil for the pre facelift cars and then one year suddenly changed their recommendation to 0W-20.
Having gone down a rabbit hole on other forums. Some people claimed the manufacturer only did this to meet MPG fuel efficiency targets. And the thinner 0W-20 doesn t have any other benefit. Some even claimed the thinner oil can be detrimental for high mileage / highly stressed engines, as it offers less wear protection.
What do you think? Is this a wacky conspiracy theory and I should stick to the manufacturers recommendation of 0W-20? Or should I use the thicker 5W-40 instead, if I want to keep my car forever and run it into the ground? Thanks.
The cars a VW Golf. With the 2 litre EA888 engine. Around 60,000 miles.
Mr Miata said:
Hi, I m wanting to do an oil service on my own. And torn between which oil viscosity to use.
The manufacturer recommended 5W-40 oil for the pre facelift cars and then one year suddenly changed their recommendation to 0W-20.
What do you think? Is this a wacky conspiracy theory and I should stick to the manufacturers recommendation of 0W-20? Or should I use the thicker 5W-40 instead, if I want to keep my car forever and run it into the ground?
Definitely a "whacky conspiracy theory" they want you to wear out your nice (newer) engine & then buy another, of course you should use the thinner less-protective oil............. The manufacturer recommended 5W-40 oil for the pre facelift cars and then one year suddenly changed their recommendation to 0W-20.
What do you think? Is this a wacky conspiracy theory and I should stick to the manufacturers recommendation of 0W-20? Or should I use the thicker 5W-40 instead, if I want to keep my car forever and run it into the ground?
E-bmw said:
Definitely a "whacky conspiracy theory" they want you to wear out your nice (newer) engine & then buy another, of course you should use the thinner less-protective oil.............
Do manufacturers really care about reliability once the car has exceeded its warranty period?the-norseman said:
FIAT/Alfa did a similar move with the 1.4 Multiair engine.
Mine is one of the later Euro 6 engines and needs the 0W oil.
I'm not sure you understand oil specifications. Nothing wrong with a Zero weight Winter oil. 0W is still way more viscous when cold than a 40 weight oil is at operating temperature. Mine is one of the later Euro 6 engines and needs the 0W oil.
You're conflating several different things which I can't really be bothered to go in to.
Thinner oil is predominantly for fuel efficiency and like for like a heavier weight oil will provide more protection than the same spec oil in a lower viscosity.
As mentioned it does seem unlikely that the 2 options are 0W-20 and 5W-40. It's more common to spec 0W-20 or 5W-30. Read up on the meaning of the multi grade viscosities. Anyone who says anything along the lines of a 0W is too thin categorically doesn't know what they're talking about, it's actually quite funny.
Either way a good quality oil changed regularly and of the correct spec then you're unlikely to go wrong and the engine should outlive the car.
Thinner oil is predominantly for fuel efficiency and like for like a heavier weight oil will provide more protection than the same spec oil in a lower viscosity.
As mentioned it does seem unlikely that the 2 options are 0W-20 and 5W-40. It's more common to spec 0W-20 or 5W-30. Read up on the meaning of the multi grade viscosities. Anyone who says anything along the lines of a 0W is too thin categorically doesn't know what they're talking about, it's actually quite funny.
Either way a good quality oil changed regularly and of the correct spec then you're unlikely to go wrong and the engine should outlive the car.
Mr Miata said:
E-bmw said:
Definitely a "whacky conspiracy theory" they want you to wear out your nice (newer) engine & then buy another, of course you should use the thinner less-protective oil.............
Do manufacturers really care about reliability once the car has exceeded its warranty period?
https://www.youtube.com/watch?v=5Ok8HcUrzeE
This video came up on my feed.
Engines tested, some using 0w-20, others using 5w30.
https://www.youtube.com/watch?v=5Ok8HcUrzeE
and here's a rebuttal of that video
https://www.youtube.com/watch?v=XyBUcxFmqn8
This video came up on my feed.
Engines tested, some using 0w-20, others using 5w30.
https://www.youtube.com/watch?v=5Ok8HcUrzeE
and here's a rebuttal of that video
https://www.youtube.com/watch?v=XyBUcxFmqn8
Edited by Smint on Monday 27th October 12:17
I'm in the camp that it's for fuel efficiency ratings, and convenience in the dealerships (one or two drums they put in everything)
Wife's 2001 Xc70, volvo originally specified 10w-40 (opie etc still show this)
Now, however, Volvo retrospectively specify 0w-30 or 5w-30.
My Father's 2007 XC90 they spec 0w-30.
My 1989 740, in the UK they provided a viscosity chart based on ambient temperature. (it was generally accepted to use a 10w-40, but being a redblock you could probably fill it with sunflower oil and it'd keep going) but in the US they specified a 5w-30.
If you go into a dealers with any of those cars now I expect they'd just fill it with the same oil they put in the brand new cars (0w-20?) and send it out the door.
At 220,000 miles the XC90 started making 'the tugboat noise' - worn out/soft exhaust lifters mean that all the exhaust cant get out through the partially open valve(s) so it then pulses back through the airbox when the intake valves open.
Some say the 30 weight oil let's this wear on the lifters happen more quickly.
Maybe, maybe not, and there is no way to ever tell for sure - but what I do know is that after thinking about it and changing to a 40 weight oil to give the lifters a bit more to 'chew on' so to speak - it stopped.
The car is now on 250,000 miles and only does it about 12-15k after an oil change when the oil gets a bit diluted with diesel (I assume), so we'll be dropping to a 10k change.
So we've eeked another 30k out of it so far when some people only get 5 or 6k before it grenades itself when persisting with the recommended grade.
After this, ive just said f
k it, and buy 5w-40 in 20 litre drums and use it in all three.
Lower on the 'w' grade is fine [the original spec for the '70 and the 740]
Higher on the 'w' grade isn't ideal for the '90 but it evidently needs the 40 weight when hot so it is what it is; since it doesnt really get that cold here and a 0w-40 would have a lot of ground to cover in terms of staying in grade etc, and it's also ruinously expensive.
(Technically the A3/B3 spec of the 40 weight oils might not play nice with the DPF on the '90 either but thats a secondary concern in that car's situation)
My 2p, not a tribologist, more a realist/pragmatist!
Wife's 2001 Xc70, volvo originally specified 10w-40 (opie etc still show this)
Now, however, Volvo retrospectively specify 0w-30 or 5w-30.
My Father's 2007 XC90 they spec 0w-30.
My 1989 740, in the UK they provided a viscosity chart based on ambient temperature. (it was generally accepted to use a 10w-40, but being a redblock you could probably fill it with sunflower oil and it'd keep going) but in the US they specified a 5w-30.
If you go into a dealers with any of those cars now I expect they'd just fill it with the same oil they put in the brand new cars (0w-20?) and send it out the door.
At 220,000 miles the XC90 started making 'the tugboat noise' - worn out/soft exhaust lifters mean that all the exhaust cant get out through the partially open valve(s) so it then pulses back through the airbox when the intake valves open.
Some say the 30 weight oil let's this wear on the lifters happen more quickly.
Maybe, maybe not, and there is no way to ever tell for sure - but what I do know is that after thinking about it and changing to a 40 weight oil to give the lifters a bit more to 'chew on' so to speak - it stopped.
The car is now on 250,000 miles and only does it about 12-15k after an oil change when the oil gets a bit diluted with diesel (I assume), so we'll be dropping to a 10k change.
So we've eeked another 30k out of it so far when some people only get 5 or 6k before it grenades itself when persisting with the recommended grade.
After this, ive just said f
k it, and buy 5w-40 in 20 litre drums and use it in all three.Lower on the 'w' grade is fine [the original spec for the '70 and the 740]
Higher on the 'w' grade isn't ideal for the '90 but it evidently needs the 40 weight when hot so it is what it is; since it doesnt really get that cold here and a 0w-40 would have a lot of ground to cover in terms of staying in grade etc, and it's also ruinously expensive.
(Technically the A3/B3 spec of the 40 weight oils might not play nice with the DPF on the '90 either but thats a secondary concern in that car's situation)
My 2p, not a tribologist, more a realist/pragmatist!
i think its done for a whisker better on emmsions and mpg ratings , if the other brand was getting 30mpg on 20w40 and your brand gets 32 mpg on 0w20 then it looks better on the papers
5/30 is still pretty thin compared to what was around years ago , id go with that (if its a wet belt then stick with dealer spec )
5/30 is still pretty thin compared to what was around years ago , id go with that (if its a wet belt then stick with dealer spec )
OP, have you done a parts number check for engine internals, or looked for a manufacturer bulletin on revision of the oil requirements? You could ask the manufacturer.
The thinner oils (in an engine designed for them) are just as good at preventing wear as thicker oils (in an engine designed for them). So, if you want to try 0w20 you need to be certain there weren't revisions of parts subject to oiling. E.g. the crank and crank bearings having a slightly closer fit.
For those thinking thinner oil is all a conspiracy... Would you rag an engine from cold? If thicker oil is better, then you don't want your oil warming up before you thrash the nuts off, do you
The important thing is to use the correct oil that the engineers designed for and validated the design with.
The thinner oils (in an engine designed for them) are just as good at preventing wear as thicker oils (in an engine designed for them). So, if you want to try 0w20 you need to be certain there weren't revisions of parts subject to oiling. E.g. the crank and crank bearings having a slightly closer fit.
For those thinking thinner oil is all a conspiracy... Would you rag an engine from cold? If thicker oil is better, then you don't want your oil warming up before you thrash the nuts off, do you
The important thing is to use the correct oil that the engineers designed for and validated the design with.But that’s assuming that the engineers have free range to do what it best. Ordinarily there is some commercial reason why oil is specified especially during a model run.
0w20 will be specified because of some marginal gains in fuel efficiency, longer term issues such as component wear will be considered as a risk but if it falls out of warranty before it goes bang then it’s another win for the OEM.
Regular changes are the key and if you drive your car in a regular way then stick to what the book says, but if you track day it or do lots of stop start journeys then you may need to look at an alternative oil. It would be interesting to see what a 200k mile engine looks like using 0w20 compared to one using a different oil
0w20 will be specified because of some marginal gains in fuel efficiency, longer term issues such as component wear will be considered as a risk but if it falls out of warranty before it goes bang then it’s another win for the OEM.
Regular changes are the key and if you drive your car in a regular way then stick to what the book says, but if you track day it or do lots of stop start journeys then you may need to look at an alternative oil. It would be interesting to see what a 200k mile engine looks like using 0w20 compared to one using a different oil
I don't know if one of the above links is to the Motor Oil Geek video. He explains that the advancement in synthetic oils means that the thinner oil not only improves fuel efficiency but has specific synthetic long chain molecules added which curl up with heat to reduce the thinning of the oil at higher temperatures. This makes it nearly as effective at higher temperatures to the thicker oil.
The issue is that those molecules degrade with shearing force so that their effectiveness reduces with use. This means that the oil will be less effective at lubrication in time. He emphasises that it is therefore important to ensure oil changes are regular i.e. make sure you get the oil changed to car manufacturers spec and make sure you are using the specified fully synthetic oils.
The issue is that those molecules degrade with shearing force so that their effectiveness reduces with use. This means that the oil will be less effective at lubrication in time. He emphasises that it is therefore important to ensure oil changes are regular i.e. make sure you get the oil changed to car manufacturers spec and make sure you are using the specified fully synthetic oils.
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