Waiting for oil temp - truth or myth ?

[rev-erend]

OK - for those who have had an oil temp guage - the engine seems to get the water hot fairly quickly but the oil temp can sometimes take an age to get up to temp.

So - is there any truth or is it a myth to let the oil warm throughly first..

The only issue I can see is it's less visceous why cold but many modern oils are 0W or 10w these days..

[Steve_D]

There are threads on this already.
Save to say I have never waited for an engine to warm up.
Unless you are about to go racing then you would normally be setting off down side roads where there will be plenty of time for the car to warm.

Steve

[GreenV8S]

What do you mean by 'first'?

If you mean before driving off, certainly not. Get driving as soon as you can.

If you mean before thrashing it, then yes.

[rev-erend]

Before thrashing it..

But why ?

[wildoliver]

Think about the engine as a ladies bits, if you jump straight in and start thrashing the living daylights out of either of them before fully lubricated results in a world of pain. Simple, crude but effective description.

[Boosted LS1]

Yep, I'd get a seizure with mine!

[rev-erend]

But surely the point here is - water is up to temp and it can be another 5 mins before oil is up to temp..

But with a modern thin oil (say 0w) - it's moving fast at that point and all parts would have expanded due to the heat anyway at that point.

If you have an oil cooler - surely that temp is lower than most of the other oil sloshing around and that does not cause a problem. After all - one of oils functions is to cool parts .. like spraying the underside of the piston etc..

Sure if it was a 20W/50 then I'm sure it may still be quite thick and not flow well and with excess revs you could end up with a lot of oil at the top of the engine and not enought in the sump for the oil pump..

[That Daddy]

Sure if it was a 20W/50 then I'm sure it may still be quite thick and not flow well and with excess revs you could end up with a lot of oil at the top of the engine and not enought in the sump for the oil pump..

[/quote]Thats unlikely to occur because the sluggish oil would just bleed past the pressure relief valve(least resistance)rather than the oil ways,thats why its bad practise to cane a cold engine before the oil as warmed thru

[wildoliver]

Look at it this way reverend, either you have hit upon a great ability to get max power from cold, and everyone else in the history of engineering is wrong, or your on a hiding to nothing. Why don't you test it on your engine

At the end of the day it doesn't matter whether your water is up to temp it's your oil that lubricates the engine.

[Boosted LS1]

^It depends on where the temp sensor is. Oil after the bearings will be very hot but the mass of oil in the sump takes longer to heat up.

[phumy]

It also concerns all the different metals getting up to temperature too and taking up all the necessary clearances. You know there is actually a difference between the size of a hot bit of metal and a cold bit, (relatively cooler), the difference could mean premature wear or even seizure.

Edited by phumy on Tuesday 29th July 09:29

[pikeyboy]

I work at rolls royce aerospace as an engine development engineer, we instruct the lads on the test beds to run at idle for 5 mins before accelerating to any sort of higher power condition, unless its a specific test or certification requirement that means we wouldnt or cant do that. we also let the engines cool down at idle too.

[Number 7]

Waiting until the engine oil is up to temperature before hitting the loud pedal will also allow the gearbox and diff. oils to warm up, which I imagine takes longer as they are further from the main heat source.

7.

[FWDRacer]

On my race motor I let the engine warm up i(dle/light rpm) in the paddock and pitlane before switching off about ten minutes prior to race and allow heat soak. That way the oil and water come up to temperatute quickly when it is thrashed away from the collecting area on the warm up lap/green light.

Thrashing an engine from cold as indicated will give you premature wear. Fact.

[movilogo]

Most cars don't have an engine oil temp gauge?

So how does one know if engine is warm (other than guessing from water temp gauge)?

[denisb]

If I don't warm my race engine up to 40-50 degrees C before giving it maximum revs it will often blow seals out. If I reduced oil pressure sufficiently to stop this happening then oil pressure would be too low by the end of a race.

For those who are about to reply "shouldn't your oil pressure relief valve cope with this"?

The answer is no.

Oil pressure relief valves aren't fast enough, and often don't have sufficient 'capacity' to cope with race engine type fluctuations (I have the data logging to prove this).

This is on a race engine with an external single stage Pace oil pump designed to cope with 9500RPM but the principle can still apply to a heavily used performance road engine.

It usually takes a warm up in the collecting area (10 minutes) followed by a lap or so at half revs.

[rev-erend]

movilogo said:

Most cars don't have an engine oil temp gauge?

So how does one know if engine is warm (other than guessing from water temp gauge)?

The later TVR's have oil temp guages.. and it's possible to retrofit them.

[That Daddy]

You dont need a oil temp gauge to tell you when to cane your road engine just common sense i have known so many people to admit to not caning the motor from cold only to be reeled in with a possible burn up and that rule goes totally out the window(what plums)

Edited by That Daddy on Wednesday 30th July 15:05

[knighty]

rev-erend said:

OK - for those who have had an oil temp guage - the engine seems to get the water hot fairly quickly but the oil temp can sometimes take an age to get up to temp.

So - is there any truth or is it a myth to let the oil warm throughly first..

The only issue I can see is it's less visceous why cold but many modern oils are 0W or 10w these days..

yes, you should let the oil warm first to something like 50 degC ish, otherwise the bearings struggle to form an adequate film and will/can scuff.......also hydraulic tappets struggle, and the oil filter will struggle........the best trick is to fit an oil to water heat exchanger.......this does two convenient things

1) it warms the oil very quickly during cold start-up, as coolant heats quicker than oil

2) it cools the oil when spanking the engine

they are common fitment on all turbo-diesel engines, get one that you can install between the oil filter and engine, as used by the likes of VW, Peugeot and Ford.

[rev-erend]

Knighty - that's superb .. knew there must be a good reason for it and I'm sure the science of oil flow and it's properties an art form in itself.