oil temp vs water temp

[PlacentaJuan]

ok i am looking at replacing my factory water temp guage, since cressida temp guages are quite unreliable.

however i would like to understand what the difference is between oil temp and water temp (apart from the fact they are different fluids, obviously).

they both circulate aroudn the engine and since the water is acting as a cooling agent surely there would be a slight lag between the engine temp increase and water temp increase, whereas the oil would heat up a lot quicker.

i also tend to think of oil and oil condition as more important than the water.

so why do all cars come with water temp guages, is it purely cost or is there another reason?

i mean if the oil is hot then the water must be hot and vice versa, is this relationship directly proportional?

[Norbie]

The water is actively cooled and regulated via the thermostat, while the oil (usually) is not. Temperatures of both fluids will usually follow the same trends but won't be directly proportional.

[IN 05 NT]

water temp heats up alot faster then the oil,

(wel atleast it does in the 23)

[ian]

it basicaly boils down to [pardon the pun ]
if your water boils its not always fatal for your engine
but if your oil gets to hot its f###d
ian

[TA23 Racer]

Oil temp will follow coolant temp as the coolant cools the entiry engine assembly so the oil gets cooled as it makes it way back to the sump. the coolant is cooling the oil as well as the engine if like. So if you have an oil cooler you can take some load off the cooling system.
Good engine oils can operate at very high temperatures Porsches air cooled engines are around 30% oil cooled and run at higher temperatures than engine with cooling jackets so if you coolant temp is O.K and you use good quality oil all should be well.

Cheers Dave.

[Hash_ra23]

it basicaly boils down to [pardon the pun ]
if your water boils its not always fatal for your engine
but if your oil gets to hot its f###d
ian

i think thats his point....so why not measure oil temp instead of water temp?

but i think its as norbie said, the water temp is being controlled by the radiator and thermostat....since its being controlled, its measured, rather than the oil temp.

[Officer Doofy]

Oil temp takes some serious constant abusive driving to get hot enough to be worried about it. Standard passenger cars dont usually see this in their day to day duties so it would be not worthwhile for manufactures to install oil temp guages on commercial cars. Water temp is way more important in standard cars. Most sports cars would have oil temp as they would be seen to be driven hard at some time of their life and oil temp would then need to be watched/considered.

[PlacentaJuan]

ok thanks guys.

since i will be keeping my standard temp guage connected then maybe ill look at an oil temp guage to complement it.

also since the water heats up a lot faster then oil temp will give a better indication of when its safe to thrash my car.

[Officer Doofy]

I would get a aftermarket water temp gauge if you have to choose jess.
The standard cressy one doesnt seem to have a very broad range. Ie when its sitting in the middle saying its all warm and good i have seen degs from 60 to 100 on my aftermarket one.

You wont really have to worry bout oil temp unless your on boost for big stints ie at the track, on the street giving it a boot full you will be ok, unless your now a uber SA street
drift0rz!

Why not just have both?

[PlacentaJuan]

coz then i have to find room for 2!!

my main concenr is to know when its safe to give full boost and i think the best way to know (other than driving if for half an hour first) would be via an oil temp guage.

my factory guage at least shows me when the engine is getting how and i DO believe it becuase if goes up when im driving up a big hill with the air con on in the heat, however i dont feel confident relying on it, so if i get an oil guage then at least i will have both, in a sense, and can compare the 2.

also it would piss me off to have 2 guages showing the same thing!, but it would be interesting to compare both temps with an accurate guage. maybe i could do one of those glovebox installations but then it would be hard to see

[big_zop]

Dont like the cost of the defi din gauges (ala Project Sleeper)?

Nengun have them for $501.43 ($537.43 delivered to NSW) which is a damn sight cheaper than i have seen from any other place.