5w/40 full synth oil
Would it be ok to use 5w40 fully synthetic oil in vp commodore v6? or would it be too thin. only reason is ive got a bottle in the garage!
If you already have it, it will do fine
IMO thats is waaaay to thin.
how man k/ms on your vp?
Just hand me the pliers.
yeah it really depends on the car as far as I know.
It will do fine. Its not what I would call ideal, but w40 will do the job if you have it sitting there.
think i will just go and buy the trusty old repco 20/40
thanks all
For external use only
It's much too thin imho. If you're on a tight budget, Castrol GTX2 (20/50) - if you care a bit more about the car, a good oil like Penrite, and 20/60 or similar.
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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Banned
If a 20W/40 oil works then a 5W/40 oil will work even better. Both oils should essentially perform the same at operating temperature with the 5W oil performing better in the time you have your car between cold and operating temperature. That's why the 5W oil is more expensive, its better.Originally Posted by jettaboy
Your vp needs a 50 grade oil? I dont know what is the original specification in the owners handbook.
For external use only
20w40 commsirac, and 15w40 in extremely cold climates. There is no reason to run a 5w40 and have the motor running on oil THAT thin at startup. Thinner oils don't work "better", although that is a popular misconception.
Given the age of the motors these days (getting on 20 years) it is only logical to move up to a 20w50 for extra protection of worn components - and having pulled a few apart, they're QUITE worn at between 250 - 350,000km
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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Banned
Oh dear, the popular misconception is that a 5W oil when cold is somehow thinner than a 50 grade oil at operating temperature, given your dramatics of claiming a thin oil at startup. This would defy the laws of nature, currently there are no oils that get thinner when colder.
You need to think of it in another way, it just hasnt thickened by the same incredible amount as a 20W oil when cold.
You really need to look at some viscosity versus temperature graphs to get a good idea. Did you realise that a 5W grade oil at 20C has ~ 12 times the viscosity of a 50 grade oil at operating temperature, ie its effectively 12 times thicker than what the motor has at operating temperature. No one has any problem with the idea of heating the oil in the sump to get it to the right viscosity for starting the motor, why should having an oil that has nearer the right viscosity when it is cold?The situation for 20W is its about double the thickness of 5W at lower temperatures(0-20C), making lubrication even more compromised at lower temperatures. The ideal would be for the oil not to thicken as it got colder.
Whether the car needs a lower W rating or not is not what has been asked here, it is whether there will be any problem putting 5W in, I say no problem!
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No, I understand what you're saying
I personally run a 15w60 in my car - I do understand the benefit of a lower rating at startup etc etc. I probably phrased it REALLY badly in my last post, it's been a while since I sleptbut I think (and this is just an opinion) that these old motors don't have the same tight tollerances as, say, an alloytec or LS2. Especially after they've been around the block a few hundred thousand times. So, and ESPECIALLY at startup, you want a more viscous oil that is going to heat up readily under compression, and is going to provide GOOD protection for your motor while it is still vulnerable.
I have experimented with 0W and 5W oils, and found nothing but loud noises and rattles on loud motors for the first 5-10 minutes. Holden recommended 20w40 for a reason
Last edited by Morton; 30-10-2008 at 11:07 PM.
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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Banned
Sure they did, because that grade of oil will serve the purpose well in the general australian climate. The very small decrease in usage costs due to better fuel consumption and longer engine life are unlikely to be offset by uisng the more expensive lower W rated oil....depends on the price of petrol compared to oil!Holden recommended 20w40 for a reason
The rate at which oils heat up is generally the same for all oils, they have near identical heat capacities. A thicker oil will get hotter more quickly though......simply because it is providing more friction.....thats why it will use more fuel. The reason the motor is vulnerable to damage when cold is that the oil is too thick and clearances between components are generally smaller
Ok I am staying right out of this, tempting as it is
For external use only
No, please doThe more opinions we can get into a discussion, the better for everyone!
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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You asked for it....
In this case 5w40 to 20w40 aint gonna make a lick of difference. Hence why I said if there is a bottle in the shed, just use it. If it was a question of a reccommendation- I would have preferred a different weight.
In theory, looking at weights alone, theory says 5w40 must be better. But:
a. Most synthetics are highly refined mineral. So my first reaction when someone says fully synthetic and sitting in the shed, chances are its mineral. That being said, if it is actually a synthetic, then it completely debunks my arguement.
b. The lower figure is generally what the base of the oil is, if its mineral oil. Polymers are added to this base to achieve multigrade viscosity. There are viscosity improvers, but these arent used to drop low temp viscosity a whole lot.
c. Shear resistance is one term used to describe the oils ability to maintain a film under pressure, through the process of hydrodynamic lubrication. This film is what reduces friction. Now there are other frictions at play, such as fluid friction, but friction between metal surfaces is what we are more concerned with.
d. (in mineral oils) You can achieve a higher shear resistance in a thicker base oil. So, you can achieve a far, far higher shear resistance, or ability to reduce friction through hydrodynamic lubrication, in a 25w60 oil, than you can in a 0w60 oil.
e. Boundary lubrication is the film that is left by good, quality oils after shutdown. This boundary lubrication is effective at reducing wear at startup. This can be easily proven using oil analasys. example. My VT is on 25w60. Yet it isnt showing signs of startup wear through analasys. Keeping in mind the lowest temp it sees is somewhere around 3-5°.
f. the 25w60 I am using is certified for use down to -20°C, providing the machine has the correct tolerances. Others performing oil analasys in australia show no sign of startup wear using various grades, from 15w to 25w. I have considered pre-pressurising/ warming systems, but providing I continue to start the engine to renew that boundary lubrication every few weeks, there is no need.
Conclusion- Due to the boundary lubrication effect of quality lubricants, there is no requirement for ultra thin cold temp lubricants in Australia. Having said that, there is no need to compromise the ability of the oil to effectively lubricate by way of hydrodynamic lubrication by reducing viscosity to such low figures.
Now this arguement also completely disregards the fact that the larger the difference between hot and cold viscosities, the more polymers are relied upon to maintain the high temp viscosities. These polymers are generally the first thing to be affected when oil is heated and cooled. An interesting fact, when I have seen quite a fair bit of evidence that Royal Purple falls out of viscosity around 7-8,000k's.
Couple of other points:
-faster warm up MAY not be a side effect of increased friction. Thicker oils flow slower, and can have a tendancy to remove less heat than thinner, faster flowing oil. Hence why when taking accurate temp readings, it is preferable to measure the machine itself, not the oil flow over it.
-thicker oil does not *always* mean increased fuel usage. Shear resistance can be increased to reduce mechanical friction enough to overcome the increased fluid friction of the thicker oil. Its amazing the power increase and fuel economy benefit I found when changing my Mazda 2 from mazda oil (castrol) 5w30 to 15w40. But when not increasing shear resistance, the increase in fluid friction will decrease economy.
Startup wear is not caused by tolerances tightening. It is caused by stationary metal surfaces sliding over each other with no lubricant between them. Those surfaces are not at all smooth- under a microscope they are extremely uneven surfaces. These uneven surfaces tear pieces off each other which are ground down to sub micron particles. Lubricants fill the gaps allowing the parts to slide.
Had enough yet???
And yes, the question was, is there any problem using the 5w40 in the shed. I think we have established there is no issue.
For external use only
A fantastic read. Thankyou so much for taking the time to post that
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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Sorry... i meant repco 20w/50... she runa lika beaydi
Banned
Yes, interesting read Bradcad, but most of it unfortunately speculative/unsupported, but not once did you mention a certain brand of lubricants.......well done.
perhaps enlighten us all on the particular "machine" you have in mind that would survive using a 25W oil at -20C?
what low figures are you talking about?, why not quote what the viscosity of a 5W/60 oil is at 20C and compare it to a 25W/60grade oil at 100C.....and tell us again which is incredibly low?
of course it is, using a higher viscosity oil requires more energy to turn the motor to the same speed, and its due to friction.....the friction within the oil stopping it moving past itself(thats what viscosity is about). This extra energy requires more fuel, which will heat things up faster due to more heat being conducted away from the cylinder head as well as the oil itself getting hotter due to the friction effects within it.
Sure, there may be some 25W oil that have just as low friction between the metal and oil as a 5W oil, but its what happening between the oil molecules which soaks up energy.
True when the motor is cold, the reduced flow with a higher viscosity oil(due to the oil pressure relief system sending most of it straight back into the sump) wont remove as much heat because as it gets to the end of its journery it will have probably got to near the same temp as the motor. However, the difference would be miniscule, the oil still ends up back in the sump and gets cooled right down again and ends up entering the motor much colder than the faster moving oil.
Interesting: its problematical on a car engine where one would actually measure the temperature .The cylinder head can vary in temperature markedly depending on load, the temp of the water or the oil passing it is much more stable. While the actual water or oil temperature is always going to be much lower than any surface from which it removes heat on the engine, it is the changes in these that occur that are useful to monitor as well as keeping track of oil and water temps so that their limitations are not met.
<---Brad Quaid = internet stalker
use it, at worst it's only in there until the next service - which i'd hope isn't any more than 10000k's away.
I used to use second hand hydraulic fluid in my farm ute. Stunk like all hell but went well!!!
For external use only
hahaha, I like that. A bit of improvisation now and then never hurt anyone ^_^
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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always gotto be some one argue for the sake of argueing. Hence why I didnt want to say anything. Interesting that it is speculative/ unsupported, when it comes DIRECT FROM TRIBOLOGISTS QUOTING PUBLISHED TEXT. Some of us better ourselves through study.
For external use only
Just ignore him
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The 1972 HQ Kingswood
The 1989 VN Turbo Rally Project
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Banned
Cmon mate, you know Ill be all over any bs on this subject.....if you cant back it up, dont post. and which tribologist, recommends 25W for -20C or supports any of the other areas Ive highlighted ^?
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