Anything wrong with 0W-40 oil?

[recaro182]

Hi, basically i am going to do an oil change this weekend, but the only oil they have at my local halfords (yes i know what your going to say!), is 0W-40 mobil 1, they dont have any 5W-40. Was wondering if this is still ok to use as im not sure what the difference is, i think it may have something to do with how thick it is???

Cheers

 

[PYE21]

I use 0w-40 Casrol Edge and thats fine (done 3 changes and 15k on it)!!!

 

[Fred@BTM]

0W, 5W, 10W are all fine to use

www.opieoil.co.uk (oilman)

 

[recaro182]

Ok, thanks guys, i will probably use 0W-40 then.

Can anyone tell me exactly what the 'W' rating stands for though?

 

[Fred@BTM]

W means Winter

the number before (ie the 0) refers to the oils viscosity at - 18deg (i think)

the lower the number means it can withstand lower cold start temps i believe

ie 0W is less thick than 10W at - 18deg

(i dunno, i'm just rambling LOL)

 

[mike]

How much is the Halfords stuff?? I'm due a 36k service in 3k but want to change the oil before then as it's not been done since I bought the car 8K ago and think it's due one!! Is the oil filter a beitch to get too, was on my valver!!!

Cheers,

Mike.

 

[TheCake]

I've used Mobil 0w-40 before and its fine.

TBH Halfords are just the retailer and its got nothing to do with them. I've used Mobil 1 oil for years.

 

[rory182]

so is 40 the weight then? I should search for Oilmans posts really shouldn't I....

I assume:
If you go for a lighter weight then you won't be getting the same protection although you might be reducing transmission losses and friction a bit.

But in using 0W40 as opposed to 5W40 you aren't changing the weight, just the temperature protection.

And I always thought the w stood for 'weight' i.e. 5weight 40, doh!!!

 

[Fred@BTM]

it might do, i don't know much about oil, i'm still learning

 

[Neil G]

I would personally run 5/40w oil....Shell Helix fully synthetic is good stuff and you can pick it up from a local garage.

 

[BRUN]

IIRC the first number relates to its viscosity @ 40c and the second number its viscosity @ 100c

0W-40 will be fine, but Mobil 1 is pricey for what it is, pm oilman for cheaper equivalents or better

 

[LegoHead]

How much is the Halfords stuff?? I'm due a 36k service in 3k but want to change the oil before then as it's not been done since I bought the car 8K ago and think it's due one!! Is the oil filter a beitch to get too, was on my valver!!!

Cheers,

Mike.

just got big bottle 4/5 litres of 5w40 for 29.99

 

[White16valver]

The way I understood was the first number is the maximum thickness when cold (so the lower the number, the thinner it is when you start and the quicker it works round the engine = good in winter) and the second number is the minimum thickness when hot (so a lower number means there's less protection between moving parts as the oil is thinner?)

I think...

LoL

 

[LegoHead]

From http://auto.howstuffworks.com/question164.htm


Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature. This page from the Sci.Electronics.Repair FAQ offers the following very interesting description of how the polymers work:

• 
  At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.
  
  
  
  
  

 

[White16valver]

What I said ^^^

LOL

 

[LegoHead]

I see that a smaller range is better, but what is the best value to start with?
5w40 seems a huge range.

 

[White16valver]

No, smaller range isn't necessarily better - you want the oil to be suitable thin at start up (the first number) and suitably thick/thin when hot (the second number), regardless of the range.

e.g. You'd want a low 'cold' number (such as the 0 in 0w40) in colder countries to allow 'better' starting due to the oil being thinner and runnier and therefore easier and quicker to pump round the engine, but you still need to maintain the correct thickness when hot, to ensure the engine is maintaining all the correct gaps between moving parts, hence sticking to the 40 'hot' number.

but you could run a 10 or 15w40 in hotter climates as the oil will already be warmer when you start up, therefore a bit runnier/thinner than it would be in the cold climate. It wouldn't need to be so thin on start up so the higher 'cold' number of 10 or 15 (or even 20) would be fine. You would still need the correct protection when hot though, so you'd stick with a 'hot' number of 40, maybe a 50 at a push.

(I think... lol)

 

[White16valver]

*waits for a techie geek who knows what he is talking about to correct him*

lol

 

[Rich]

On a modern car 0w-40 should be fine, but in an older car and it will mostly end up out the exhaust on start up!

 

[BRUN]

No, smaller range isn't necessarily better

it is, as less viscosity additives are needed

 

[J273]

My oils running low and need to top it up...Its done just over 7000 miles and is due for its forst 2yrs service in july time so should have a full oil change then (if this matters) .....what i want to know is what sort of oil should i be topping up with ... im pretty sure its still on its origional oil from new ...is it ok to mix or not???

Thanks

 

[LegoHead]

My oils running low and need to top it up...Its done just over 7000 miles and is due for its forst 2yrs service in july time so should have a full oil change then (if this matters) .....what i want to know is what sort of oil should i be topping up with ... im pretty sure its still on its origional oil from new ...is it ok to mix or not???

Thanks

from my research i guess it wont be a good idea to mix different oils due to the different additives, as one oil has exactly the right additives to make it work properly, adding different ones will upset the balance.

but 5w40 is recommended by loads of ppl on here and thats what i have gone with.

btw my oil is empty after 4000 miles of driving, the light came on.

 

[rory182]

dont rely on the 'oil-ok' press the stick daily to bring up the level and check the oil physically regularly too. You dont want your engine running dry for any amount of time.

 

[BenR]

it is, as less viscosity additives are needed

synthetic oils dont run polymers like multigrade, well the good ones. And if they do, they are far more uniform so do not react or cause problems like multi's.

 

[-TA-]

wheres oilman! hes the god of all things oil! :clown:

 

[oilman]

0w-40 is fine although Renaults recommendation is 5w-40

This is how it works!

A short lesson on Multigrades:

If you see an expression such as 10W-40, the oil is a multigrade.

This simply means that the oil falls into 2 viscosity grades, in this case 10W & 40.

This is made possible by the inclusion of a polymer, a component which slows down the rate of thinning as the oil warms up and slows down the rate of thickening as the oil cools down.

It was first developed some 50 years ago to avoid the routine of using a thinner oil in winter and a thicker oil in summer.

For a 10w-40 to attain the specification target a 10W ( W = winter) the oil must have a certain maximum viscosity at low temperature. The actual viscosity and the temperature vary with the viscosity grade but in all cases the lower the number, the thinner the oil, e.g. a 5W oil is thinner than a 10W oil at temperatures encountered in UK winter conditions.

This is important because a thinner oil will circulate faster on cold start, affording better engine protection.

For a 10w-40 to attain the other specification target a 40 oil must fall within certain limits at 100 degC. In this case the temperature target does not vary with the viscosity grade, if there is no "W", the measuring temperature is always 100degC. Again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC., which is typical of maximum bulk oil temperatures in an operating engine.

The engine makers are, of course, very well aware of this and specify oils according to engine design features, oil pump capacities, manufacturing tolerances, ambient temperature conditions etc. It is important to follow these guidelines, they are important and are an are stipulated for good reasons.

If the engine has been modified, the operating conditions may well be outside the original design envelope. The stress on the oil caused by increased maximum revs, power output and temperature may indicate that oil of a different type and viscosity grade would be beneficial.

Cheers
Simon

 

[oilman]

As a rule, the narrower the viscosity gap the more stable the oil will be.

EG, a 5w-40 (35) will be more stable than a 10w-60 (50)

This will explain some of the questions on this thread:

Why do oils lose viscosity with use?

Viscosity Index Improvers.

An oils viscosity will decrease as the engine temperature rises. Viscosity Index Improvers are added to reduce this thinning. They are a key addative in the production of multigrade oils.

VI Improvers are heat sensitive long chain, high molecular weight polymers that minimise the viscosity loss of the oil at high temperatures. They work like springs, coiled at low temperatures and uncoiling at high temperatures. This makes the molecules larger (at high temps) which increases internal resistance within the thinning oil. They in effect "fight back" against the viscosity loss in the oil.

"Shearing"

The long chain molecules in VI Improvers are prone to "shearing" with use which reduces their ability to prevent the oil from losing viscosity. This "shearing" occurs when shear stress ruptures the long chain molecules and converts them to shorter, lower weight molecules. The shorter, lower weight molecules offer less resistance to flow and their ability to maintain viscosity is reduced.

This shearing not only reduces the viscosity of the oil but can cause piston ring sticking (due to deposits), increased oil consumption and increased engine wear.

Like basestock quality, VI Improvers also vary in quality. As with many items the more you pay, the better the finished article and more expensive, usually synthetic oils are likely to incorporate better VI improvers. All other things being equal the less VI improver an oil contains, the better it will stay in grade by resisting viscosity loss.

Which oils require more VI Improvers?

There are two scenarios where large amounts of these polymers are required as a rule.

Firstly in "wide viscosity span" multigrades. By this I mean that the difference between the lower "W" number and the higher number is large for example 5w-50 (diff 45) and 10w-60 (diff 50) are what is termed as "wide viscosity span" oils.

Narrow viscosity oils like 0w-30 (diff 30) or 5w-40 (diff 35) require far less VI Improvers and therefore are less prone to "shearing".

Secondly, mineral and hydrocracked (petroleum synthetic oils) require more VI Improvers than proper PAO/Ester (Group IV or V) synthetic oils as they have a higher inherent VI to begin with, this is due to differences in the molecular structure of the synthetic base oils compared to mineral oils.

It is a fact that many synthetics require significantly less VI Improver to work as a multigrade and are therefore less prone to viscosty loss by shearing.

Cheers
Simon

 

[Fred@BTM]

Simon here's a question for you

we were using Silkolene 5w40 pro race

But it seems the oil has got too hot and has buggered the engine, 10W60 instead now you think???

 

[oilman]

What do you mean by too hot?

Cheers
Simon

 

[Fred@BTM]

as in its got to over 130 degrees and the oil has "broken down"

 

[Neil G]

I don't know how it could have broken down and caused problems

I used 5/40w in my old Subaru with no problems and the heat it generated was way more than the Renault.....the oil was more 'stressed' if you like as it had to lubricate hot turbo bearings.

 

[BenR]

dont you have an oil cooler, and so you have an oil temp gauge?

 

[oilman]

as in its got to over 130 degrees and the oil has "broken down"

How long were you running at these temps?

The Pro S 5w-40 is happy for long periods at 120deg without shearing down, peak is 150+ in short bursts, yes its at its limit but it wont let go.

What has the oil done to bugger the engine exactly?

Cheers

Simon.

 

[edde]

I used 10-60 now instead of 10-40 and its much better on track oil pressures are much better instead of 1 bar there now at 2.5 constant and temsp seem a few degrees lower.
The 172/182's can use upto a 15-60 oil if you want but that would be in hot climates for track use IMO. But Renault say it can be used as low as 10 degrees or somehting I forget from memory.

 

[browno]

as in its got to over 130 degrees and the oil has "broken down"

Sounds like you need a big(ger?) oil cooler there then Fred...

Some great stuff there again Oilman...
I spend my days developing new lube additives, for a large additive company, and am always impressed by the depth of the explanations given in your articles... Top stuff!

 

[Fred@BTM]

i don't know the exact temps its reached, the bores are glazed and the rings were buggered, no other damage apart from that, i'm saying its oil

 

[BenR]

wasnt an issue with the oil IMO, as glazing would of occurred earlier on and not a consequence of oil temps.

 

[Fred@BTM]

consequence of what then boyo??

its not surge, i can't figure out the cause

 

[BenR]

surge?

glazing is almost always a result of incorrect bore prep/running in. OEM now finish bores to the level where running in with synthetic oil is not required to plateau the hone.

If the oil was too hot and lubrication was lost, its more likely that you would find the bearing area could not support the rings as the hone hatch is used to support the micro film of oil, which prevents the rings from touching the bores once they have seated. SO, if they were too hot, support is lost and accelerated wear would occur.

 

[Fred@BTM]

there is scoring also

i understand what you mean