View Full Version : 15w40 or 10w40
Andyvalver
15-11-2005, 18:48
Which is best for the f7p engine? I give my car a dailly thrashing too :)
I currently use 15w40 :?
i've used 10w40 shell helix
and 10w50 silkoline pro s race oil
Silkoline defo keeps tghe temps down a bit better initially, but doesn't last, haven't noticed a differnece in running between the 2, on the lookout for some 15w50 to try.
At the end of ther day its what suits your car
Andyvalver
15-11-2005, 18:51
Yours isnt f7p is it? :? Good advise anyhow :P
VIPERONE
15-11-2005, 18:52
10 40 is good 15 50 is a tad thick...but will still suffice, just take a few just take a few more minutes to warm up, to alter the viscosity of the oil
Andyvalver
15-11-2005, 18:53
So 15w50 is better for winter and for thrashing? :twisted:
Viscous means thick, it starst off thinck and becomes thicker, ie loosing viscosity
VIPERONE
15-11-2005, 19:12
the viscosity of the oil is the thickness. heat alters this variable to make the oil thin, hence when you first start your car up the oil is thicker, and pressure is high, as it warms it thins reducing pressure, :- thats why you shouldnt rag an engine form cold.
Andyvalver
15-11-2005, 19:15
Surely you want oil to stay not too thick but not too thin like water? Also thicker oil is better for hot running engines? :?
If you check posts from Oilman on other forums, doubt you need a 50 grade oil. Even some exotica doen't need oil that high temp rated according to him and he lives/breathes oil.
What is more important is the lower rating for cold start protection. a 10 or 15w won't give as good protection from cold which is where most damage is done. I've used 0w40 Castrol RS which I found to work really well. Now using 5w40 Silkolene Pro S. Last oil I used was Mobil 1 Motorsport 15w50 which I found to be worst oil I have used. There was no way I was gonna risk using that in Winter.
If you want some 15w50 Lunner have about 6 litres spare.
Going on what you have just said i think i'll go for some 5w40 or 5w50 and see how that compares
Will use up the Mobil 1 motorsport stuff next summer as it may be OK for summer but definately wouldn't recommend it to anyone and car is running so sweet on the Silkolene Pro S put in at weekend.
Think someone on ebay is selling 0w40 Castrol RS for 15 quid a bottle (4 litres). Worth getting 3 to cover two changes and top ups.
best oil I've ever used is one thats bloody hard to get hold of in petrol stations!
Duckhams Q 15W-40 (I know its 15W but it warms up pretty quickly)
I used to buy it on the company card like mad but the garage I used doesn't take allstar fuel cards anymore and I simply can't find anywhere in Blackburn, Darwen, Bolton thats does it!
hang on a sec
5W40, 10W40, 15W40 are all the same thickness??? (at 99degC???)
5, 10, 15 refers to the oils viscosity when cold???? (at a certain temp)
5W-40 fully synthetic
15W-50 is too thick for winter definitely, you could use it in the summer but i still think its too thick unless your engine is worn
I use 10w40 semi or 5w 40 fully synth if I know I'm doing a trackday or summut.
MatBrown
16-11-2005, 02:24
Motul 15w50 for me.
Got a 25L drum.
Mat.
If you check posts from Oilman on other forums, doubt you need a 50 grade oil. Even some exotica doen't need oil that high temp rated according to him and he lives/breathes oil.
What is more important is the lower rating for cold start protection. a 10 or 15w won't give as good protection from cold which is where most damage is done. I've used 0w40 Castrol RS which I found to work really well. Now using 5w40 Silkolene Pro S. Last oil I used was Mobil 1 Motorsport 15w50 which I found to be worst oil I have used. There was no way I was gonna risk using that in Winter.
If you want some 15w50 Lunner have about 6 litres spare.
Totally agree with you on Mobil 1, worst oil I have ever used. Very tappety cold starts (even in summer) and burns off so quickly, I used to get about 500 miles to 1 litre of oil!!!! Now use Shell Helix 10/40 and can say I am very happy so far, no tappety cold starts, temp never seems to go above 100 even when thrashing it, and doesn't burn off as quickly!
Yup, mobil is shit, and isnt'r cheap either, had a mate who used to swear by it, persuaded him to try shell helix, hasn't looked back since
VIPERONE
16-11-2005, 17:45
long live halfords mineral 10 40
BigBoreBri
16-11-2005, 18:58
I cant fault the normal ELF Competition SX 10/40 Stuff for general use, hot or cold its great... Id recomment silkolene for more aggresive driving! :twisted:
Beware Mobil1, its horrible piss thin oil! :roll:
So whats the advantage of semi/fully synth over mineral oil?
BigBoreBri
16-11-2005, 19:11
So whats the advantage of semi/fully synth over mineral oil?
I would like to know that too... Not sure what its like on engines but ive seen mineral oil perish seals on disk brakes before?! :?
i THINK it needs changing more, but not sure
the benefits of fully synth over mineral are numerous
fully synth has a longer drain interval for one, far better protection for another
one of the main ones, is, once mineral oil reaches a certain temp it will break down, once this has happened it will never be the same again and the protection it offers is far less
So gunner is talking crap .......again :wink: :lol:
He's always full of shite :P
I use 5/40....but putting in 10/40 as it getting a tad cold and tappy :oops:
hang on a sec
5W40, 10W40, 15W40 are all the same thickness??? (at 99degC???)
5, 10, 15 refers to the oils viscosity when cold???? (at a certain temp)
Yup which is what everyone here is talking about. Don't need a 50 heat rating in a Valver or a Willy but the lower the cold figure the better it will protect in winter.
Not much different to how much screen wash or anti freeze concentration you use in summer/winter. Change your oil to suit conditions.
Check posts from Oilman (Simon from Opie Oils) on most forums, sadly not this one and you will get a better understanding of oils.
Oh and Silkolene Pro S in 5w40 is making my car run very sweet at the mo. Loving it but then did have Mobil 1 15w50 in before so thats like going from 95 Ron to 99 Ron in petrol terms.
Lifted from somewhere else:
I read on many forums about 0w and 5w oils being too thin. I will try to explain it without getting over technical and well go from there.
0w-40, 5w-40, 10w-40 and 15w-40 are all the same thickness (14cst) at 100degC.
Centistokes (cst) is the measure of a fluids resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid.
As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC.
So, all oils that end in 40 (sae 40) are around 14cst thickness at 100degC.
This applies to all oils that end in the same number, all oils that end in 50 (sae 50) are around 18.5cst at 100degC and all oils that end in 60 (sae 60) are around 24cst at 100degC.
With me so far?
Great!
Now, ALL oils are thicker when cold. Confused? Its true and here is a table to illustrate this.
SAE 40 (straight 40)
Temp degC.........................Viscosity (thickness)
0..........................................2579cst
20..........................................473cst
40..........................................135cst
60..........................................52.2cs t
100........................................ 14cst
120.........................................8.8cst
As you will see, there is penty of viscosity at 0degC, in fact many times more than at 100degC and this is the problem especially in cold weather, can the oil flow quick enough to protect vital engine parts at start up. Not really!
So, given that an sae 40 is 14cst at 100degC which is adequate viscosity to protect the engine, and much thicker when cold, how can a 0w oil be too thin?
Well, it cant is the truth.
The clever part (thanks to synthetics) is that thin base oils can be used so that start up viscosity (on say a 5w-40 at 0degC) is reduced to around 800cst and this obviously gives much better flow than a monograde sae 40 (2579cst as quoted above).
So, how does this happen, well as explained at the beginning, its all about temperature, yes a thin base oil is still thicker when cold than at 100degC but the clever stuff (due to synthetics again) is that the chemists are able to build these oils out of molecules that do not thin to less than 14cst at 100degC!
What are the parameters for our recommendations?
Well, we always talk about good cold start protection, by this we mean flow so a 5w will flow better than a 10w and so on. This is why we recommend 5w or 10w as the thickest you want to use except in exceptional circumstances. Flow is critical to protect the engine from wear!
We also talk about oil temps, mods and what the car is used for. This is related to the second number xw-(XX) as there may be issues with oil temperatures causing the oil to be too thin and therefore the possibility of metal to metal contact.
This is difficult to explain but, if for example your oil temp does not exceed 120degC at any time then a good "shear stable" sae 40 is perfectly capable of giving protection.
"Shear stability" is important here because if the oil shears it thins and thats not good!
However, if you are seeing temperatures in excess of 120degC due to mods and track use etc then there is a strong argument to using an sae 50 as it will have more viscosity at these excessive temperatures.
There are trade offs here. Thicker oils cause more friction and therefore more heat and they waste power and affect fuel consumption so its always best to use the thinnest oil (i.e. second number) that you can get away with and still maintain oil pressure.
There is more but this post is too long already so lets keep it to basics.
Cheers
Simon
And more:
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 straucture 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
And in a nutshell:
"5w flows more quickly when you turn the key in any temperature and therefore less engine wear. 90% of wear occurs on cold start".
Cheers
Simon
And finally (Why synthetics are better oils):
I thought this would be of interest as Its probably the question I get asked the most. Shame the answer isnt simple though!
The basic benefits are as follows:
Extended oil drain periods
Better wear protection and therefore extended engine life
Most synthetics give better MPG
They flow better when cold and are more thermally stable when hot
Esters are surface-active meaning a thin layer of oil on the surfaces at all times
If you want to know the reasons why then please read on but, warning - Long Post!
Stable Basestocks
Synthetic oils are designed from pure, uniform synthetic basestocks, they contain no contaminants or unstable molecules which are prone to thermal and oxidative break down.
Because of their uniform molecular structure, synthetic lubricants operate with less internal and external friction than petroleum oils which have a non-uniform molecular structure.
The result is better heat control, and less heat means less stress to the lubricant.
Higher Percentage of Basestock
Synthetic oils contain a higher percentage of lubricant basestock than petroleum oils do.
This is because multi-viscosity oils need a great deal of pour point depressant and viscosity improvers to operate as a multigrade.
The basestocks actually do most of the lubricating. More basestocks mean a longer oil life.
Additives Used Up More Slowly
Petroleum basestocks are much more prone to oxidation than synthetic oils. Oxidation inhibitors are needed in greater quantities in petroleum oils as they are used up more quickly.
Synthetic oils do oxidize, but at a much slower rate therefore, oxidation inhibiting additives are used up more slowly.
Synthetic oils provide for better ring seal than petroleum oils do. This minimizes blow-by and reduces contamination by combustion by-products. As a result, corrosion inhibiting additives have less work to do and will last much longer in a synthetic oil.
Excellent Heat Tolerance
Synthetics are simply more tolerant to extreme heat than petroleum oils are. When heat builds up within an engine, petroleum oils quickly begin to burn off. They are more volatile. The lighter molecules within petroleum oils turn to gas and whats left are the large molecules that are harder to pump.
Synthetics have far more resistance as they are more thermally stable to begin with and can take higher temperatures for longer periods without losing viscosity.
Heat Reduction
One of the major factors affecting engine life is component wear and/or failure, which is often the result of high temperature operation. The uniformly smooth molecular structure of synthetic oils gives them a much lower coefficient friction (they slip more easily over one another causing less friction) than petroleum oils.
Less friction means less heat and heat is a major contributor to engine component wear and failure, synthetic oils significantly reduce these two detrimental effects.
Since each molecule in a synthetic oil is of uniform size, each is equally likely to touch a component surface at any given time, thus moving a certain amount of heat into the oil stream and away from the component. This makes synthetic oils far superior heat transfer agents than conventional petroleum oils.
Greater Film Strength
Petroleum motor oils have very low film strength in comparison to synthetics. The film strength of a lubricant refers to its ability to maintain a film of lubricant between two objects when extreme pressure and heat are applied.
Synthetic oils will typically have a film strength of 5 to 10 times higher than petroleum oils of comparable viscosity.
Even though heavier weight oils typically have higher film strength than lighter weight oils, an sae 30 or 40 synthetic will typically have a higher film strength than an sae 50 or sae 60 petroleum oil.
A lighter grade synthetic can still maintain proper lubricity and reduce the chance of metal to metal contact. This means that you can use oils that provide far better fuel efficiency and cold weather protection without sacrificing engine protection under high temperature, high load conditions. Obviously, this is a big plus, because you can greatly reduce both cold temperature start-up wear and high temperature/high load engine wear using a low viscosity oil.
Engine Deposit Reduction
Petroleum oils tend to leave sludge, varnish and deposits behind after thermal and oxidative break down. Theyre better than they used to be, but it still occurs.
Deposit build-up leads to a significant reduction in engine performance and engine life as well as increasing the chance of costly repairs.
Synthetic oils have far superior thermal and oxidative stability and they leave engines virtually varnish, deposit and sludge-free.
Better Cold Temperature Fluidity
Synthetic oils do not contain the paraffins or other waxes which dramatically thicken petroleum oils during cold weather. As a result, they tend to flow much better during cold temperature starts and begin lubricating an engine almost immediately. This leads to significant engine wear reduction, and, therefore, longer engine life.
Improved Fuel Economy
Because of their uniform molecular structure, synthetic oils are tremendous friction reducers. Less friction leads to increased fuel economy and improved engine performance.
This means that more energy released from the combustion process can be transferred directly to the wheels due to the lower friction. Acceleration is more responsive and more powerful, using less fuel in the process.
In a petroleum oil, lighter molecules tend to boil off easily, leaving behind much heavier molecules which are difficult to pump. The engine loses more energy pumping these heavy molecules than if it were pumping lighter ones.
Since synthetic oils have more uniform molecules, fewer of these molecules tend to boil off and when they do, the molecules which are left are of the same size and pumpability is not affected.
Synthetics are better and in many ways, they are basically better by design as they are created by chemists in laboratories for a specific purpose.
Cheers
Simon
Might be worth getting the salient points in a sticky post somewhere as guess a lot of that info will be often used when people come to change their oil.
Nice posting Matty!
If you lot have any questions, please feel free to ask.
Cheers
Guy.
Going back to the original question, neither!
I would use 5w-40 synthetic.
There are some good race ones for those of you who use your car on track or like to give it a good thrashing all the time.
http://www.opieoils.co.uk/TechSpecs/PRO%20S%20-%204%20Wheel.pdf
http://www.opieoils.co.uk/TechSpecs/Mobil%20and%20Motul/300VPower.pdf
Or for non abuse use, you can't go wrong with these
http://www.opieoils.co.uk/TechSpecs/Mobil%20and%20Motul/8100_X-cess_5W-40_3682.pdf
http://www.opieoils.co.uk/TechSpecs/titan%20supersyn%20sl%205w_40%20&%20sl%205w_50.pdf
I have plenty to choose from here:
http://www.opieoils.co.uk/lubricants.htm
Cheers
Guy
im using total elf quartz 5w 40 in my baby! and it runs like a dream? was on offer when i got some from GSF about £15 for 5 litres???
I use 5W 40 mobil 1.....however I have just put in a litre of 0w 40 by mistake will that do any harm?....it can get very cold here in the Winter
I pay £7 a litre....
I use 5W 40 mobil 1.....however I have just put in a litre of 0w 40 by mistake will that do any harm?....it can get very cold here in the Winter
I pay £7 a litre....
Nope,
That will be fine.
No need to pay £7 per liter, next time give me a call :wink:
Cheers
Guy.
oilman! how much you knocking 5 liters of total quartz 9000 fully synthetic 5w 40 out for???
oilman! how much you knocking 5 liters of total quartz 9000 fully synthetic 5w 40 out for???
Ok,
We only have the 5w-40 left in one liters and we are phasing it out so there is a deal to be done.
Give me a call on 01209 215164
Cheers
Guy.
phasing it out???? whats the alternative then once its all gone??? and why doesnt your site show any prices???
phasing it out???? whats the alternative then once its all gone??? and why doesnt your site show any prices???
Well, theres plenty of alternative, and to be honest better quality for similar money, we will be replacing it with Amsoil.
As for prices, keep your eyes peeled as we will have an online shop coming in the enew year.
In the meantime for prices, drop me a mail to sales@opieoils.co.uk
Cheers
Guy.
Is the above recomendations the same for the 1.8 8v, F3P engine?
Is the above recomendations the same for the 1.8 8v, F3P engine?
Yep. :D
CHeers
Guy.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.