Assuming a bonnet costs £100 to respray, does anyone have any ideas/guesses as to how much it would cost to respray the whole car...Magnum grey perhaps?

Rough ideas welcome.
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Adam Read more

I suspect the EGR valve on the NC Astra is sticking, which sometimes causes rough running. I'm considering temporarily blanking the port from the exhaust to see if that gets rid of the problem, hence confirming the EGR valve as the culprit.

Are there any reasons why I should not do this? Can it cause any lasting harm to the engine?

Number_Cruncher
Read more

I used the windscreen wipers for the first time today and I'm gutted to see that the previous owner has used Rain-X or something similar on the screen, it's working great on the side windows, but it reduces visibility to zero when using the wipers on the front. :-(

I know that the stuff wears off eventually, but does anyone know of a way to speed this up? Obviously the formula is designed to resist general cleaning with glass cleaner etc. so I was wondering if anyone knows of a household chemical that may start to remove it? I was thinking White Spirit perhaps or does it not have to be as strong as that?

I don't really want to just let nature take it's course, I'm too impatient!

Blue Read more

More Excellent information from Oilman. Taken from the thread Oil Viscosity

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Oil Viscosity

It's thicker when cold 10w instead of 5w (poorer cold start protection) and thicker when hot sae 40 instead of 30 (will withstand higher operating temps).

This may be of help:

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

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Also see Simon's latest contribution on the subject of oil HERE

And some more stuff:-
Gear Oil Questions and Answers
16 important OIL questions answered
What does 10w-40 mean..?
Read more

Discussion in another thread touched on the life of shock absorbers and it was suggested that 80--100k should be regarded as a reasonable life. Are there any other views on this, or information from official or manufacturing sources? Read more