Upgrade engine oil?

[phildini]

Shit I have been using 10-40 semi syn. is that bad News???

:cry: Shit I have been using 10-40 semi syn. is that bad News???

No need to worry, the 10w-40 grade is suitable for your car, you can use a good semi synthetic with regular oil changes no problem.

However if the car sees track/spirited use or modifed than a fully synthetic is well worth thinking about.

Cheers

Guy.

[simontaylor]

10w-50 5w-40, can someone explain to me what these numbers are about, thanks.

It refers to the oils viscosity 10w -40 .The W stands for winter when the oil will be most viscose.

The actual two numbers relate to the viscosity 'weight' and relate to cold and hot behaviour. Im not quite sure what the temp is they use as 'cold' but the 'hot' is 100 degrees c. So a 15w 40 would flow like a 15 weight oil when cold and at 100 deg, like a 40 weight.

http://www.engineersedge.com/lubrication/oil_viscosity.htm

This should help to explain in plain english.

What is this thing called viscosity?

It’s written on every can of oil and it’s the most important visible characteristic of an oil.
The viscosity of an oil tells you how it reacts in certain circumstances and how it performs as a lubricant.
When a oil is subjected to external forces, it resists flow due to internal molecular friction and viscosity is the measure of that internal friction. Viscosity is also commonly referred to as the measurement of the oils resistance to flow.

There are two methods of viewing an oils resistance to flow. Firstly there is Kinematic Viscosity which is expressed as units indicating the flow of volume over a period of time and this is measured in centistokes (cSt).
An oils viscosity can also be viewed by measured resistance. This is known as Apparent Viscosity and it is measured in centipoises (cP).

However in the real world an oils viscosity is also referred to in such terms as thin, light and low etc. This suggests that the oil flows or circulates more easily. Conversly, terms such as heavy and high etc suggest the fluid has a stronger resistance to flow.

The reason for viscosity being so important is because it is directly related to the oils load-carrying ability - The greater an oils viscosity, the greater the loads that it can withstand. (It must be added when new not over a period of time as all oils “shear down” with use)

An oil must be capable of separating the moving parts in your engine at the operating temperature. On the basis that an oils viscosity is related to its load carrying ability, you could be fooled into thinking that “thicker” oils are better at lubricating but, you’d be wrong in this assumption. The fact is that in the wrong application a high viscosity oil can be just as damaging as using a low viscosity oil.

The use of an oil that’s too “thin” can cause metal-to-metal contact, poor sealing and
increased oil consumption and conversely, an oil that’s too “thick” can cause increased
friction, reduced energy efficiency, higher operating temperatures, and poor cold starts in cold temperatures.

It is very important that you select the correct oil, not too “light” or too “heavy” and your Owners Handbook is a very good place to start as it lists the temperatures and options.

Oils thicken at low temperatures and thin as the temperature increases. The actual rate of change is indicated by their viscosity index (this number normally listed on the oils technical data sheet indicates the degree of change in viscosity of an oil within a temperature range, currently 40-100 degrees centigrade)

An oil with a high viscosity index, will normally behave similarly at these two temperatures but an oil with a low viscosity index will behave quite differently. It will become very fluid, thin and pour easily at high temperatures. A higher index is better!

Multi-grade oils are designed to perform at high and low temperatures by adding polymers to a base oil (5w,10w, 15w etc) which are heat sensitive and “uncoil” to maintain the higher viscosity sae 30,40,50 etc. This means that the oil can be used “all year round” rather than using different oils for summer and winter.

It is important to understand that the selection of the correct oil for your car is not just guesswork, you must consider the temperatures at which you need the oil to operate a 0w, 5w oil is better for cold starts as the oil circulates more easily when it’s cold and is able to flow around the engine more easily and quickly, offering protection at the
critical moments following cold engine start-up. These oils are also known to give better fuel economy and engine performance.

Finally, all oils “shear” or thin down with use and this means that an oil that started life as a 10w-40 will with use become a 10w-20. The period of time this takes depends on the type and quality of the oil. The most “shear stable” oils are proper Synthetics, either PAO (Poly Alph Olefins) or Esters which have very high thermal stability. They are in general of the more expensive variety but last longer and give the best levels of protection.

Cheers
Simon

Who is that masked man
Thanks OM.

Just changed my oil for 10w-50. Hopefully it'll do the trick!

Should do but please keep me posted.

Cheers
Simon

Will do. Thank Guy for his help.




(ps. I can't believe this is my 100th post. Just posting it to get over 100!! )

I have tried all sorts of oils in my gtas and found Halfords fully synthetic a very good option , about £25 ,mobil 1 really is too thin .
I am doing a change in a couple of weeks and recomendations of what to try this time is good ,also i was advised NOT to change thi filter too often as it works better as it gets older . any thoughts ?

I have tried all sorts of oils in my gtas and found Halfords fully synthetic a very good option , about £25 ,mobil 1 really is too thin .

Mobil 1 is not too thin.

If you take the Halfords own 5w-40 and the Mobil 1 0w-40, they are both exactly the same viscosity when up to temp.

So the only way it can be seen as too thin is at the cold crank viscosity of the 0w, however this is only marginally thinner then a 5w.

Cheers

Guy.

Hi,
Do you know if Millers do a suitable oil for my Alpine A610? I use their fully synthetic in my Volvo turbo and their classic SAE 20W/50 in my V8 Rover P5B. I never compromise on oil quality but Millers seem to make top spec oils without the huge advertising budgets and hence retail prices.
Their fully synthetic meets the higher spec laid down by both Porsche and BMW and is used by various race teams so I assume it is good stuff.
What part of Kernow are you in? I am down there in my A610 next month.
Best regards
Geoff

Hi,
Do you know if Millers do a suitable oil for my Alpine A610? I use their fully synthetic in my Volvo turbo and their classic SAE 20W/50 in my V8 Rover P5B. I never compromise on oil quality but Millers seem to make top spec oils without the huge advertising budgets and hence retail prices.
Their fully synthetic meets the higher spec laid down by both Porsche and BMW and is used by various race teams so I assume it is good stuff.
What part of Kernow are you in? I am down there in my A610 next month.
Best regards
Geoff

Geoff,

I am not overly familiar with the Millers range quality wise as I have never had the correct tech data for comparison.

We recomend the Silkolene Pro S 10w-50 ester pao synthetic.

Tech data here http://www.opieoils.co.uk/lubricants.htm

We are based down in Redruth, Cornwall. As a point of useless info I was hatched in Farnham.

Cheers

Guy.