I get asked all the time "why do you advise against the use of 10w-60?".

 

Let's get one thing clear, I supply 10w-60 and recommend it where it is appropriate for the engine or the application but conversly I caution against it's misuse!

 

I have debated this many times on many car forums and I know there are some that do not agree with me however I have never had a reasonable technical explanation why 10w-60 is in fact suitable, it's certainly not mentioned in the handbooks of many modern highly tuned performance cars, with the exception of some Alfa Romeos for "spirited driving" whatever that is meant supposed mean.

 

Explaining this is diffucult so there may be questions but I'll try my best to explain it in plain English!

 

Lets look at what oil specs actually mean and particularly the higher number which is in fact the oils SAE number (the "w" number is in fact the cold crank viscosity and measured in a different way) The SAE number is measured by the oils viscosity at 100degC.

 

Your cars require according to the manufacturers specs, sae 30, 40 and in some cases sae 50.

 

To attain the relevent sae number the oil has to be at 100degC (no thinner than)

 

SAE 30 11cst approx

SAE 40 14cst approx

SAE 50 18cst approx

 

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.

 

SAE 60 is in fact 24cst viscosity at 100degC!

 

This is 33% thicker than an sae 50, 70% thicker than an sae 40 and over 100% thicker than an sae 30!

 

So, what's the problem with this thickness?

 

Well, this is measured at 100degC and at lower temps (70-90degC) all oils are thicker than at 100degC so the problem is compounded to some extent.

 

The downsides of such a thick oil (when not specified) are as follows:

 

Additional friction, heat and wear.

A reduction of BHP at the wheels

Lower fuel consumption

 

The thicker the oil is the more friction and drag and the more power the engine needs to move it around the engine which inevitably translates to less at the wheels.

 

So, when do we spec a thicker oil?

 

Well, you will probably have seen us on occassions recommending a 10w-50 but only in these circumstances.

 

1. If the car is heavily modded and heat/oil temperatures are excessive.

2. If the car is used on track and heat/oil temperatures are excessive.

3. If it's required by the handbook.

 

Our criteria for this is based on oil temps as an sae 40 semi-synthetic can handle around 110degC for limited periods whereas a proper synthetic sae 40 can hande 120-130degC for prolonged periods due to its thermal stability.

 

Once you see more than say 120degC for prolonged periods an sae 50 is adviseable as it is 18cst at 100degC and still 11cst at 130degC! This is in fact the same as an sae 30 at 100degC.

 

More importantly at 90degC an sae 40 is 15cst, an sae 50 is 20cst and an sae 60 is 30cst!

 

In a worst case scenario with thick oils (when not required) is that you will experience air entrainment and cavitation inside the bearings at high RPM. Not clever stuff!

 

I know this is technical stuff but oil is a combination of science and engineering and few people know enough about it to make an informed choice. Just because your mates use it and have had no problems is not a good enough reason to use it, your engine would prefer and benefit from the correct oil.

 

Cheers

Simon

My recommendations are all in my oil advce thread and have been for a long time, just take a look.

 

To subscribe as a trader I would need to talk to the Club and the admins to agree a way forward.

 

RP, I had some tested back in the summer and there were some interesting results but not for discussion on a public forum. You can always email me off the boards though.

 

Cheers

Simon

 

We need a chat about commision you were giving the club Simon,are you still on the same email?

@ 98.9 'c cST 5.4

@ 37.8 ºC, cSt 29.0

@ -40 'c, cST 11,000

 

mean anythink to you? :D

 

Yep, its very very thin.

 

Cheers

Simon

We need a chat about commision you were giving the club Simon,are you still on the same email?

 

Yep, sales@opieoils.co.uk

 

Look forward to hearing from you.

 

Cheers

Simon

I'm picking a car up in a few days that has oil cooled turbos, do you think it might be better to use 10w-60 in that case? I can imagine the oil will get rather hot indeed under load!

 

I'd have preferred water cooled turbos but there you go. I'll just have to stick a bigger oil cooler & oil temp sensor on the car to compensate.

 

Shaun the car has been running on RS10-60 and has been fine if a ZTech recommended oil is not used the warranty will be void ;)

Shaun the car has been running on RS10-60 and has been fine if a ZTech recommended oil is not used the warranty will be void ;)

 

well i guess that clears that one up! :D using RS10-60 (pinched it of Yamez) its the first time i have used it so ill have to see what i think!

:confused:

 

So to sum up, is 10/50 fully synthetic the best oil to use for both TT and NA

 

:confused:

To sum up it depends on the state of tune an style of driving.

 

We tend to recommend 10w-50 if the car is modded or used on track and running oil temps higher than 120degC.

 

If the car is stock and used on the road and running standard oil temps of 80-110degC then 10w-40 or 5w-40.

 

The stock Nissan Recommendations for these cars (depending on ambient temperatures) is sae 30, 40 or 50.

 

We have found the Silkolene PRO S 10w-50 to work well in these cars and give higher protection when hot to cars that are either modded or driven hard.

 

I can post Nissans recommended grades for NA and TT here but you will find that I've posted them before if you do an advanced search under username oilman.

 

Cheers

Simon

what about the castrol oils that have just been released! "supposed" to be the best they have made yet! any info on that stuff?

http://www.castrol.com/castrol/productdetailmin.do?categoryId=9004869&contentId=7008974

You still dont need a 10w-60 for oil cooled turbos, oil cools by moving fast, the faster you can get it to move/take away heat the better.

 

Go no thicker than an SAE30 or else that oil will start to slow down.

 

Cheers

 

Simon.

 

Aha, makes a lot of sense.

 

Cheers,

Shaun

You mean "edge".

 

It certainly looks better on paper than RS but then again costs a lot more!

 

Cheers

Simon

Hey Oilman, long time since I've seen you post on Pistonheads. I wondered where you were lurking!

 

Do you think the "Mobil 1 0W-40 is too thin" arguement applies to Zeds as well?

 

Cheers,

 

Ian A.

In theory no it shouldn't be, its the same as any other 40 oil at 100degC and 40 times thicker at 0degC.

 

However many say it's not suitable, some with valid reasons.

 

Cheers

Simon

Hi, can you get hold of Silkolene Comp 2 Premix by any chance? If so, could you give me details of cost & delivery. It's going in my microlight ;)

 

Cheers,

Shaun

Sure can.

 

Drop me a mail to sales@opieoils.co.uk and I will forward on a bike oil price list for you.

 

Cheers

 

Guy.