Economy benefits of increasing (starting) oil temp

[Shannow]

http://www.ukintpress-conferences.com/uploads/SPKEX15/Day3_7_Frank_Will.pdf

It's a presentation rather than a paper, but is pretty interesting nonetheless.

Warmup fuel economy benefits are more by heating the oil (dropping the viscosity) than heating the block.

(and commentary that the drainback from the heads, is "cool", not much higher than coolant temperature, as it's in contact with expansive liquid cooled surfaces...whoda think it ???)

 

[JHZR2]

That's sensible from a fuel economy standpoint (pumping losses), but I'd think that a higher viscosity would be helpful if the warming components have different CTEs and are in a transient state of temperature and condition.

A circulating oil heater would be the best bet Id think...

 

[Kuato]

Hmmm...kind of accomplishes the same thing as a lower viscosity oil...

Wonder if there's a test out there on fuel economy with lower vis oil and a higher vis pre-warmed oil.

 

[SonofJoe]

There's a lot to digest in this presentation but my initial reaction is as follows...

Anything that gets engine oil up to normal operating temperature as soon as possible and importantly, keeps it there, is IMO a very good thing. And yes, I agree that such a measure would result in better fuel economy and lower emissions (although the degree of savings would rather depend on whether you lived in Finland or Singapore with the colder countries having most to gain).

Having said that, I would not rate the chances of this technology ever being widely adopted. My reasons for saying this have nothing to do with the technology itself and everything to do with the attitudes and collective psychology of the OEMs.

IMO, the OEMs have evolved into being 'problem shifters' rather than being the 'problem solvers' they should be. The truth is that the OEMs could have developed appropriate engine tech to control and maintain oil temperature decades ago. I'm a chemical engineer so I know this kind of thing isn't rocket science! However what we saw was the OEMs off-load the problem of improving fuel economy, more or less wholesale, onto the oil companies. The result was the trend to ever thinner oils. This way the OEMs minimise the manufacturing cost of their vehicles but shift the cost on to the customer by way of ever more expensive oils. They have also off-loaded the problems which can be caused by ever thinner oils onto customers in the sure and certain knowledge that these will occur out of the warranty period.

You could argue that they did similar things when it came to exhaust after-treatment. With gasoline three-way catalysts, rather than put a few more pennies worth of platinum on the substrate, they chose to (a) restrict the level of ZDDP (or Phosphorus to be more exact) in oil and then (b) impose a Phosphorus Volatility restriction on the Sequence IIIG which pushes oils to use a higher percentage of heavier ZDDP, adding cost to the oil at nil cost to the OEM. Likewise, when it came to reducing diesel emissions, rather than introduce tech that actually worked (like the stuff they're now being forced to introduce) and not third-rate DPF's which coke-up at 60,000 miles, they send the oil companies off to develop low SAPs oils in the vain hope that this will get them through.

Maybe I'm wrong. After Dieselgate, maybe the OEMs will start getting their own house in order and start figuring out 'proper' fundamental fixes to some of these issues. Maybe the tectonic plates are shifting...but I'm not holding my breath...

 

[UltrafanUK]

The issue is that a good reliable pre heater is expensive, as it needs to heat both the oil AND coolant. The fuel burners that have a text and timer system are even more expensive and more of an OEM only fit.

A simple oil pan only stick on heat pad can reduce rich mode warm up time by about half, which is good news in both main block wear and exhaust system (DPF and EGR in particular) function. Alas the cost of the electric will be about the same as the fuel saved.

If you have a vehicle that lacks engine underguards, make sure that if your garage does not have earth leakeage circuit breakers to fit one to the socket used AND even if it does, fit the correct fuse size.

If CAFE regs were based on cold engine figures I'm sure a simple plug in heat pad would be a standard fit.
It would also help long engine life fans if the oil consumption limits in most new car warranties were cut to a more reasonable figure. 1 liter in 1K miles is truly nuts!

 

[Jetronic]

the oil use limits are getting cut. The limits are half of what they used to be for some brands.

 

[SonofJoe]

I was thinking about this in the bath...

The engine coolant system is thermostatically controlled. The coolant isn't routed through the radiator until it comes up to temperature which in my experience is pretty quick. I would have thought contacting oil and coolant through some sort of heat exchanger would make more sense than contacting oil and exhaust gas (and just not opening the radiator until both the coolant AND the oil are upto temperature). Designing a simple, sealed, finned aluminium pipe to carry warming coolant through the sump shouldn't be that difficult or expensive.

The other thing I was thinking about was oil heating at the first turn if the key. An electrical pad heater works but why do you need to heat ALL the oil in the sump? Why not just electrically heat the oil that the oil pump takes in the first 15 seconds (or whatever the first gallery charge corresponds to), after which warm oil will start running back to heat the sump naturally. Just heating the first charge of oil, and then shutting off the current would probably keep the amperage required to sensible levels and shrink the size of the resistance heater.

If a combination of first-turn-of-the-key electrical heating plus a coolant heated sump could knock extreme low temperature start-ability on the head, then you don't need super-thin, volatile engine oils. If you can then engineer in some form of oil temperature control, then you probably don't need super-thick oils either because in extremely hot climates at maximum load, you would just set the controller to run the oil cooler. If you don't need super-thin or super-thick, then you don't need VII and if you don't need VII, then you don't need as much DI and the oil becomes cheaper and less volatile.

Simples!

 

[SR5]

Very interesting points Joe. I too worry that it's a race to the bottom as many of the car manufacturers cut what they can from their production costs, as long as it looks shiny and new to the customer, and lasts the standard company lease term.

Preheating a charge of oil makes sense too, but if the extra alternator load adds to the fuel consumption, you are back at square one. I mean it's a good engineering idea in terms of engine design, it just may not help enough with cafe regs. The trouble is the metrics have become the final goal, rather than a secondary aid to help gauge the bigger picture.

Why don't they just make the fuel economy test a little more standardized, with standard issue tyres, fuel and oil. That way the focus is shifted back to the core car design, not the add-ons that change over time.

 

[Jetronic]

In my diesel, it takes at least a half hour of driving to get the coolant temp up to normal if the outside temperature is about 0°C and driving on more or less level ground within legal speed limits. A lot of heat of course gets shedded into the passenger cabin, and in fact until that gets up to temperature the coolant never reaches normal levels.

There's an oil/coolant interchanger present already. I'm sure the coolant circuit is pulling heat from the oil until the cabin heater is calming down. And that's with EGR being routed through a cooler aswell which helps heating up the coolant.

The temperatures are slightly positive today (6°C) and as it happens I've got to bring the wife to a friends gathering. I'll time the coolant heating cycle. 12 km there, and I'll have to go uphill the first mile which helps the coolant heating up.

 

[Shannow]

Have been travelling a lot the last half week, and been pondering dieselgate, and exactly the issues that you two (Joe and SR5) have here (in between working other more esoteric stuff which gets me to the pondering).

You (the OEM) are scored on getting score X, in test Y.

Is it really cheating if in circumstances other than test Y, you change the tuning (for example to provide better corner exit performance ) ?

If yes, then your standard test is wrong

 

[Jetronic]

no it's not cheating.

But if the driver is driving in the same circumstances as the test (excepting never turning the steering wheel and not being stationary etc) the driver should be able to have the same result as in the test. If not, it IS cheating.

 

[SR5]

It's not cheating if they put a switch on the dash and the driver many select power or economy mode. The problem is if power mode breaks emission rules, not just a reduction in mpg.

 

[Ducked]

Originally Posted By: SonofJoe
I'm a chemical engineer so I know this kind of thing isn't rocket science!


Sure it is.

Stevenson's Rocket.

I have thought for a while that if you had a wee fire tube stylee boiler in your exhaust system you could blow steam through a hollow dip-stick and/or a steam grid on the bottom (inside or outside, depending on bravery level) of your sump. Maybe use copper brake pipe.

Steam has the advantage that it's naturally regulated to an appropriate temperature.

Direct electrical heating has the disadvantage that it tends to overcook the oil, and it isn't "free".

 

[demarpaint]

That's very interesting. When searching for an oil pan heater I read of a few people who plug in their oil pan warmers when temps reach 45F. Maybe they're onto something?

 

[Shannow]

I honestly beleive that Holden are trying the accomplish this with the sump design on my car...

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3692871/What_we_Holden_doing_-_sump_de

 

[09_GXP]

Very interesting. The exhaust to oil heat exchanger sounds similar to the exhaust to coolant heat exchanger on the Prius. It's also worth noting that for cars that have piston cooling nozzles (PCN) the oil gets up to temperature much more quickly and will vary much more over a drive than without PCNs. I would be interested to see the fuel economy benefits of a GDI car with and without PCNs.

 

[Jetronic]

Originally Posted By: Jetronic
In my diesel, it takes at least a half hour of driving to get the coolant temp up to normal if the outside temperature is about 0°C and driving on more or less level ground within legal speed limits. A lot of heat of course gets shedded into the passenger cabin, and in fact until that gets up to temperature the coolant never reaches normal levels.

There's an oil/coolant interchanger present already. I'm sure the coolant circuit is pulling heat from the oil until the cabin heater is calming down. And that's with EGR being routed through a cooler aswell which helps heating up the coolant.

The temperatures are slightly positive today (6°C) and as it happens I've got to bring the wife to a friends gathering. I'll time the coolant heating cycle. 12 km there, and I'll have to go uphill the first mile which helps the coolant heating up.


6.5°C out.

Started the car at 11:57, since we were ready to, I was told
Finally moved off at 12:00, since we weren't all quite ready to go, it seems
Going uphill immediately, the heater started blowing at 12:02.

12:06 the needle of the coolant gauge moved the first time. Supposedly 51°C. 4 miles from home.
12:07 60°C
12:08 70°C
12:09 80°C
12:11 90°C. The thermostat starts to open between 80°C and 90°C, this is very evident on the gauge as the needle pauses. 8 miles from home

Very light traffic, could run the speed limit everywhere, no waiting to give way etc...

I had the heater on recirc aswell to increase the heat up times. Cabin temperature set to 20°C.

This car gas piston cooling nozzles, and a heat exchanger between oil and coolant, and an EGR heat exchanger.

 

[SonofJoe]

Originally Posted By: Shannow
Have been travelling a lot the last half week, and been pondering dieselgate, and exactly the issues that you two (Joe and SR5) have here (in between working other more esoteric stuff which gets me to the pondering).

You (the OEM) are scored on getting score X, in test Y.

Is it really cheating if in circumstances other than test Y, you change the tuning (for example to provide better corner exit performance ) ?

If yes, then your standard test is wrong


I really am absolutely the wrong person to answer this question!

In my days making the slippy stuff, I used every single dodge and wheeze I could think of to get oils to pass those pesky engine tests. There was no area of wriggle room I would not stoop to exploit to the max in order to keep costs down. I acquired something of an unsavoury and unethical reputation (especially with my so-called colleagues in the US) but most of what I did was either technically within the rules (albeit only just) or done in a grey area where the rules themselves weren't particularly clear. I won't say there weren't occasions when I totally crossed The Great Ethical Divide but when the customer says 'Do this and keep your gob shut!', is it actually cheating???

I often used to muse to myself that one day I would write a book titled 'How To Cheat At Oil Formulation And Get Away With It!'. Anyone know a good publisher?

 

[SonofJoe]

Originally Posted By: SR5
Very interesting points Joe. I too worry that it's a race to the bottom as many of the car manufacturers cut what they can from their production costs, as long as it looks shiny and new to the customer, and lasts the standard company lease term.

Preheating a charge of oil makes sense too, but if the extra alternator load adds to the fuel consumption, you are back at square one. I mean it's a good engineering idea in terms of engine design, it just may not help enough with cafe regs. The trouble is the metrics have become the final goal, rather than a secondary aid to help gauge the bigger picture.

Why don't they just make the fuel economy test a little more standardized, with standard issue tyres, fuel and oil. That way the focus is shifted back to the core car design, not the add-ons that change over time.



I guess where I was coming from with the small electrical heater thing was something just to get oil flowing (as opposed to trying to pump gel and starving the bearings of oil). If you say a 10W-xx oil is pumpable at -25C and is guaranteed gel free at -30, you would only ever need the electrical heater to function in very extreme, cold climates by say 5C. Most of the time, it would not be required.

Once the engine has started and oil is flowing, I'd see it as the job of the coolant/oil sump heat exchanger to get the oil temperature up quicker than would otherwise be the case without a heat exchanger. To my mind, it wouldn't matter that the oil temperature was SLOW to get up to say 100C as long as it came quicker from cold because that avoids handling the oil at the lowest temperatures when viscosity is at its highest.

 

[fdcg27]

Originally Posted By: UltrafanUK

If CAFE regs were based on cold engine figures I'm sure a simple plug in heat pad would be a standard fit.


CAFE numbers are derived from the emissions certification tests that must be performed for every passenger vehicle and light truck sold in the US.
These tests include a cold start, since they're intended to model actual car use. There is both a city cycle, from which the city FE numbers are derived and a highway cycle. The highway cycle FE numbers as reported are reduced by a factor to make them more representative of what owners will actually see since the highway cycle involves what have always been slower speeds than anyone actually drives on an interstate.