water temp

[mkh1357]

hi guys
I have bought an audi A6 ,made 2003 recently. since It is my first Audi car ,so I am not sure if my car is running well or not. the first thing which I am worried is water and oil tem. the water temp will go to 95 after 2-3 km driving and the oil temp is always between 65-70. is it any thing wrong with the system?anybody can help me please?

 

[Bobtech]

Those temps are good as long as neither exceed the 100 or 90 respectively for anything other than a hot traffic jam. The fast warm-up is typical of Audi, the hotter an engine runs without overheating, the better for performance and mpg. Don't forget, under pressure, the coolant won't boil till over 120 degs anyway. (Laws of physics and all that).

If the cooling fans cut in and out again fairly quickly when hot stationary, that shows a cooling system with good flow. The fact that the fan cuts in and out at all is ok.

 

[mkh1357]

thanks bobtech for your response. I checked my car in highway today. the water temp is fixed on 95 but oil temp was moving between 70-95 . should the oil temp stay in a fixed temp or not?
thanks

 

[enda1]

Oil temp will vary depending on how you are driving. If you thrash it the temp will go up

 

[Bobtech]

enda1 is dead right, water temp will stay more or less constant, but oil temp will rise virtually to water temp at high speeds and drop around 10 - 15 degrees poodling around town.

My S6 4.2 temps are very similar to yours under those two extremes of motoring. If oil consumption is ok and you are not losing coolant, I would'nt worry unduly.

Oil temp gauges, in my opinion, are a bit of a waste of time unless hoofing round Silverstone for the afternoon. I think an oil pressure gauge is more useful, but, there we are!

 

[bar shaker]

Oil temp is important. You should try to get the oil close to 100degC as regularly as possible, to evaporate the water molecules out.

Cars that are used in town end up with oil that looks like yellow syrup because water has condensed inside the engine and has not been boiled back out.

Given the choice, it would be an oil pressure gauge but temps are important too. The oil pressure warning lights are set at such low pressures they may as well show a grave stone with 'Engine - RIP' on it.

 

[mkh1357]

thanks bar shaker
so,i should be happy when seeing oil temp going up to 100? is the oil temp related to the water temperature?

 

[bar shaker]

Yes, very happy. The oil isn't at optimum lubrication until its above 85degC.

They are connected and most cars have a water to oil heat exchanger, although its more of an oil heater to get the oil temp up after start up, rather than to get the temp down when on a full throttle run. The oil plays a big role in engine cooling and you will see higher engine temps when your oil level is low, even on cars without oil coolers.

The oil temp will always be higher and will rise more quickly on an engine that's already warm. This is because oil is being sprayed onto the bores and the under side of the pistons, where as the water is in a jacket around the outside.

The golden rule is that both should be 'Goldilocks'... neither too hot nor too cold.

 

[Bobtech]

Again I agree with one of the posters, "bar shaker". Creamy syrup inside the engine is not at all good (from town driving). It can take around 25+ miles to get the oil temp up sufficiently to evaporate the water content from the sump. Too many short runs can cause internal corrosion, particularly around the valve train.

By the way, I wasn't suggesting that oil temp is unimportant, of course it is, as bar shaker has said, it's just that oil pressure can tell you more about engine condition and before the lights come on to say "Big Time Knocking in 3 - 2 - 1", a drop from the regular indication is quickly seen on a gauge before it's too late.

Can I also add that using the correct and approved oil grade in any engine, regardless of its cost, is money well spent. It is the life blood of the engine and you will economise at your peril!