OIL for V70 T5

[oilman]

I thought you might say that
Got a website that takes orders?
I did a google on "oilman silkolene", you've been a busy fella!

http://www.opieoils.co.uk

[oilman]

Any comments on this Simon ? Yes indeed!


0w-40, 5w-40, 10w-40 15w-40 and 20w-40 are all the same thickness (14cst) at 100degC.

Centistokes (cst) is the measure of a fluid's 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? It's 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 can't 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, it's 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 that's 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 it's 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

[SaffronC70]

Great, thanks for your time Simon !

[weasel]

'There is more but this post is too long already so lets keep it to basics.'
nope, simon the more you write the better, which also saves me going for world records in googling!

[siamblue]

Simon that is a cracking read, I am using 5w 40 in my car and was thinking of going over to 10w40 as i thought the 5 was a bit too thin, but as you have pointed out it is actually better for the car

Gary

Keep up the good input mate,

[dicky b t5]

Me V70R is going in for a oil change in the morning.....

And its going to get...10W 40 Semi Synth....so i'll see how it goes..

[SaffronC70]

Right, I've been thinking about this far too much now and am still undecided . . .

Simon, the preferable oil grade for my 100k turbo engine is a decent fully synth, high ester content, reputable 5w-40.

This will provide as good as and beyond protection as a semi-synth 10w-40.

Correct ?

Thanks

[weasel]

recommended minimum spec hths for a porsche is exceeded by castrol gtx magnatec 10w40.... oh and the honda nsx recommended oil is..... not synthetic!:-))

[SaffronC70]

I was thinking of going back to good 'ole Magnatec, you read so much stuff on this internet, decisions become very complicated !

Next topic . . . what coolant should I go for ?! lol

[weasel]

lol that should be a separate thread!

[lance]

Im no expert , but I really rate magnatec 10-40 it doesnt use a drop between services and stays clean looking longer even though its still fairly clean when I change it after just 5k. Ive had my car 18 months and done 30k in her now showing 156k.
My previous 854T5 (winnie ) loved magnatec too!
My mrs 854T5 will be getting the magnatec treatment too on the next service ,hers only gets a 10k change, cos its stock and doesnt get treated quite as hard as mine (fnar fnar)

[Engineer]

Simon that is a cracking read, I am using 5w 40 in my car and was thinking of going over to 10w40 as i thought the 5 was a bit too thin, but as you have pointed out it is actually better for the car

Gary

Keep up the good input mate,

Yup those tapping hydraulic tappets in your high mileage engine sound lovely in the morning lol.........

[siamblue]

Yup those tapping hydraulic tappets in your high mileage engine sound lovely in the morning lol.........

I didn't think the oil dropped off the tappets does it not coat them after standing still or is there full run off?

Gary

[Engineer]

I didn't think the oil dropped off the tappets does it not coat them after standing still or is there full run off?

Gary

Only pulling your leg lol, but as you ask its aeration of the oil in wide tolerances nothing to do with run off etc.

[dicky b t5]

Use what Volvo Recommend 10w-40...... I've heard some bad things about using fully Synth
oil......To thin & gets to hot......But thats only what i've been told..!!

I'm sure this will cause a few comments....lol..!

I said over a month ago 10w-40.......If it's good enough for Volvo, Its good enough for me.

This has been a really good reading Thread, But still no positive out come..!

I'm gonna stick with the 10-40....lol

[weasel]

oh dear it's all going horribly wrong isn't it simon? why does the silkolene pro s say 'race' on the datasheet and on the can? :-)

[SaffronC70]

I said over a month ago 10w-40.......If it's good enough for Volvo, Its good enough for me.

This has been a really good reading Thread, But still no positive out come..!

I'm gonna stick with the 10-40....lol

What if you use a fully synth 5w-40 - engineered to outperform 10w-40 ?

jokes !

[Engineer]

What if you use a fully synth 5w-40 - engineered to outperform 10w-40 ?

jokes !

You don't engineer oil lol, you mix it that's why they call them that do, chemists lol

[weasel]

and pao's are made from..... waste oil and mineral shale!

[BlackBeast]

and pao's are made from..... waste oil and mineral shale!

Dude, just leave it go!