how to "guess" oil temperature

[Jakegday]

hello all. my grand prix, like every other car ive ever owned, has a water temperature gauge, but does not have an oil temperature gauge. im curious about my oil temp so i can know when my 5w30 oil reaches 30 weight. im not doing anything with this info, like i said, im just curious.

im assuming the oil temp is not the exact same as the water temp at all times...... so my question is how can i use my water temp gauge to guess my oil temp? my car has a 180 degree thermostat (since thats what the aftermarket PCM calls for) so does my oil NEVER get over 180 degrees?? or does the oil get hotter then the water? im guessing the water heats up faster then the oil, and if that is the case, about how long does it take the oil to reach the same temp as the water? and how long does it take to reach 100 degerees celcius after that?

i know i could have worded this question ALOT better but i hope you all get the jist of it and have some input......

 

[Familyguy]

In a properly tuned engine at operating temperature, the water and oil temps should be approximately the same.

 

[MGregoir]

The oil heats up and cools more rapidly than the oil.

Atmospheric conditions have more effect on oil temperature as there is no thermostatic temperature control of the oil.

 

[Jakegday]

Originally Posted By: MGregoir
The oil heats up and cools more rapidly than the oil.


maybe i should have been able to figure this out by reading the rest of your thread, but i wasnt... could you please correct this?

 

[Kruse]

Buy a non-contact thermometer and find out. There are cheapies out there that are under $30. After you use one, you will find how convenient they are and use it in more areas than your car.

 

[Kruse]

Originally Posted By: Jakegday
Originally Posted By: MGregoir
The oil heats up and cools more rapidly than the oil.


maybe i should have been able to figure this out by reading the rest of your thread, but i wasnt... could you please correct this?


I'm sure he meant coolant.

 

[Gary Allan]

Quote:
so my question is how can i use my water temp gauge to guess my oil temp?


You can't ..at least beyond the notion that it will be somewhere near it at some point. Your water temp will be reached relatively quickly. Your normalized (for whatever state you're in) oil temp ... will not.

There's a loose interrelationship between oil and coolant temp, but I view it as thermal pressure and outlets. Your jackets provide 180F of sustained thermal backpressure. The exhaust and oil see (most of) the rest. The rad bleeds off excess ..and will bleed off more excess as the oil approaches the same temp.

 

[MGregoir]

Yeah...I meant oil heats up faster than coolant. Every day is a Monday in my world.

 

[zrxkawboy]

Originally Posted By: MGregoir
Yeah...I meant oil heats up faster than coolant. Every day is a Monday in my world.


I believe it's the other way around.

 

[MGregoir]

Once at temperature, the oil temperature will rise faster under load and fall faster than water temperature. It does take longer than coolant to initially heat up but the temperature is far less stable than water temperature.

 

[Gary Allan]

Originally Posted By: zrxkawboy
Originally Posted By: MGregoir
Yeah...I meant oil heats up faster than coolant. Every day is a Monday in my world.


I believe it's the other way around.


Not by a long shot. Even in exchanged engines oil trails coolant by a wide margin in time to temp.

Now it will shed temp rather quickly when switching from load to unloaded (non-exchanged). That is, you're traveling down the road @ 220F+/- and let off the gas, it may slam right down to 190+/- and then creep up again as power is applied.

The sustained combustion process maintains the current oil temp. Eliminate the level of thermal production, the thermal byproduct will be reduced.

 

[saaber1]

Originally Posted By: Gary Allan
...Even in exchanged engines oil trails coolant by a wide margin in time to temp.


I have been keeping track of people who are tracking their warm up time on euro engines and it always seems to be somewhere around 7-9 minutes for coolant and somewhere around 20 min. for oil temp. (I assume the internal parts follow shortly after oil temp).

I have heard those numbers enough that I feel those times are a good rule of thumb for most Euro engines (not acocunting for excessively high or low ambient temps of course). Does that sound like a reasonable rule of thumb?

 

[Gary Allan]

Small sump exchanged engines will reach oil:coolant equilibrium in about 9miles/minutes. They're usually at the minimum coolant temp much sooner. The coolant temp will be somewhat "locked down" to near the thermostat threshold until the oil reaches a point where it can't soak up enough heat from the coolant to keep it at that state. The larger the sump in relationship to the thermal mass being produced, the longer it will take to level off.

No engine should take 9mile/minutes to reach approximate normalized coolant temp. The emissions would be prohibitive.

A non-exchanged engine will take that long (20minutes+/-) for normalized oil temps (assuming a normal sized sump).

 

[tripleM]

And the answer is...?
Still waiting...

 

[Quattro Pete]

Originally Posted By: tripleM
And the answer is...?
Still waiting...

The answer to what? There is no simple way to "guess" oil temp. It varies by engine design. In some engines it's about the same as coolant, while in others it may be a bit higher or a bit lower, assuming coolant stays at around 190F.

And as has been said before, during warm-up, coolant reaches 190F before the oil does. Oil temp will typically drag by 5-10 mins.

 

[CATERHAM]

Originally Posted By: Kruse
Buy a non-contact thermometer and find out. There are cheapies out there that are under $30. After you use one, you will find how convenient they are and use it in more areas than your car.


I don't know accurate that method is.
Presumably you're taking a reading from the side of the oil sump, if you can get to it. Is that the same as the oil temp at the pick-up point?
Secondly, that method doesn't work so well when your driving the car so peak oil temperature will never be known.

If you car doesn't come with an oil temp sensor then you are pretty much left to installing one plus an oil temp gauge.

BTW, for us motor oil nerds, it's one of the most informative least expensive upgrades you can make to your car.
It's the ONLY way to accurately determine your engines oil (grade) viscosity needs for the way you use your car.

 

[Gary Allan]

+1 on the oil-geek-nerd quotient potential. Just that gauge alone ..or in conjunction with a butt dyno ..and you can have a great time. Next would be a trans temp for those with automatics.

I'm only half ..no ..make that 1/3 kidding

 

[mechtech2]

Jakegday - Even with your 180 thermostat, the oil can for sure get much hotter than that. Of course, on a short run in cool weather, it will be much cooler that 180.

How hard you are accelerating, and high speeds, really heat up the oil. So does ambient temperature.

There is no way to know for sure unless you measure the oil's temp.
And even then , it makes a big difference WHERE you measure it.

Don't worry about if the oil is 'up' to a 30 . It is actually thicker when it is cooler.
Our concerns are oil that is too hot, and may therefore be too thin. I can smell an engine that is too hot. A real gauge is nice, but once again, WHERE is going to make a big difference.

And if that is a street car , consider getting a 195 thermostat in there. It is better for fuel efficiency and the engine. For a tuner to mandate a cooler thermostat, all he is doing is allowing a bit more ignition advance, for a few HP - kinda cheating. All around, it is not a good idea and they should work around the stock thermostat. Of course, pure racing is another story.

 

[CATERHAM]

A good and fairly easy to install sensor location is in the drain plug, if it's mounted horizontally.
Drilled and tapped plugs are readily available for that purpose.
The big question is where are you going to install the gauge particularly in a late model car that's esthetically acceptable.

 

[HTSS_TR]

I really like to know the oil temp in my cars, if Scan Gauge can read the oil temp I would buy it without second thought, but it can read the coolant temp only. I want to know my use of thinner oil for the way I use my cars is valid or not.