How long before engine oil is fully warm (petrol & diesel)?

[VeeFource]

Using my torque app I can geekily monitor how warm the coolant is getting for my engine, though it doesn’t seem to detect oil temperature so I can really only use it as a rough guide. I’ve noticed my diesel’s coolant takes up to 20 minutes to warm up driving conservatively whereas the other half’s petrol only takes 5.

Although the diesel is more efficient (the reason for the longer warm up time), I work on the basis this also means it has more time to conduct the heat to the oil. Am I right in thinking the oil will be almost fully warm by the time the coolant is? How long should you give it for the petrol’s oil to be fully warm seeing as the heat won’t have had chance to conduct to the oil in such a short time?

Opinions from those of you with oil temp gauges or any engine experts would be very welcome

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Prinny said:

Does anyone know if these bmw oil gauges are ‘accurate’ - i.e. are they the same as the modern water temperature gauges that do cold > normal > hot, but don’t actually represent the ‘real’ value?

I would question where the oil temperature gauge is on the system as having now fitted an oil temperature gauge to the sump plug of my car it takes about 5 miles before it even starts registering over 50°C and about 10 miles for it to be up to it's baseline running temperature of 80°C. My car is only a 1.6 four banger though so yours will probably warm up quicker to be fair.

Looking at the viscosity chart for the oil I use, there's not a lot in it over 70°C so I'll start to work the engine then but only fully stretch it once it's over 80°C as this is when it's virtually at it's thinnest.

[VeeFource]

A500leroy said:

id like to fit a pre heater to my daily, any suggestions?

I've looked into these a bit. Seems the easiest and cheapest practical option is to fit a mains powered sump heater which is basically an adhesive backed pad at a cost of around £100. They look to help reduce warm up time a bit and probably some engine wear.

However there's the school of thought that most of the engine wear occurs in the first few seconds after startup due to their being a lack of oil rather than it being too cold and viscous. So not sure if it's worth the hassle/risk of problems/risk of driving off still plugged in. Also, the gearbox (and in some cases final drive boxes) oil will still be cold unless you put heaters on those as well.

[VeeFource]

spookly said:

Given that most modern cars will easily crack 150k+ miles (and often many more) without the engine being opened, as long as they have regular oil changes, I'd say you are probably overthinking things.

True, but then how many horsepowers will they have lost by then? Up to a third if some of the episodes of Top Gear are to be believed and most of that will will be down to engine wear.

Baldchap said:

I wait for the blue light to go out or the gauge to read warm.

The Tesla gets thrashed from ice cold!

That just means your coolant is up to temperature. The oil takes over twice that time again to get up to 80°C based on my experience.

Also a friend of mine did a PHD in battery technology and says even they need warming up (ie using fairly gently at first) to prolong the life of the battery. Hard to say how long it would take to get a car battery pack warm mind.

[VeeFource]

Petrolsmasher said:

But there isent much difference in oil viscosity between 30 and 90 degrees in a modern oil like 5w30 so does it matter much really?

A quick bit of googling shows the kinematic viscosity of 0W30 is about 4-5 times higher at 30°C vs 80°C.

Spare tyre said:

Of course the time of year and how long the car is parked makes a big difference

My oil temp gauge is located in my oil sump plug and amazingly it only takes 5 mins for the oil to cool from 80+°C to ~65°C. It's not like it shoots back up again when continuing to drive either, though it is a bit quicker than warming up from stone cold.

[VeeFource]

No one's saying your engine is going to explode if you don't let it warm up. It's about reducing wear which helps prevent losing horsepowers and some fuel efficiency as the miles go by.

Edited by VeeFource on Sunday 19th May 15:22

[VeeFource]

Condi said:

Have you got any proof of this?

The Top Gear rolling road tests were generally done on unserviced cars, and from memory some new oil, spark plugs etc returned much of the performance. I would think with a modern engine you would see little difference between a brand new motor and one with 150k on, provided they had been serviced in line with the book. Certainly I've never noticed much change in performance or economy as cars age.

I don't have data on it. But increased engine wear can't help with those things can it?