Fast warm up ideas: Oil to coolant heat exchanger
 

If you have a diesel truck you probably already have one. So :thumbup:
But gasoline trucks may be lacking or have an air to oil cooler. Which is what you don't want in the winter.
Yes most have a thermostat but everyone I have tested l allow at least some oil though.
Cars pretty much never have an oil cooler.
But the engine oil in a car can take roughly double the miles to warm up as compared to the coolant.
There was an old post on here about it but I can't seem to find it.
My big block Chevy had an oil to air cooler.
I am going to replace the air to oil cooler with an oil to water cooler. A stainless steel 40 plate 250psi rated heat exchanger.
I bought this heat exchanger to do a coolant to ATF heat exchanger but have since decided to go with a manual transmission.

Have you measured oil and coolant temp independently? I would think the engine would warm up the oil pretty quick if the coolant and block were already warmer.

I don't have a temperature gauge but the oil pressure gauge will give a good indication of when the oil is warm.
On a freezing morning the coolant temperature on my fire bird will come up to operating range from a cold start after about 6 miles. The oil pressure doesn't drop into the normal pressure range until at least 10 miles.

Another reason for the oil/coolant heat exchanger is about this time last year it was about 0°F. I cranked up my 7.4L and it was knocking really bad. Before I fired it up I had ran the 5,500w coolant heater for the normal amount of time, then continued to run it for about 5 minutes. Because I thought it might be air in the lifters. After it didn't go away I figured it could be a rod bearing.
A few days later when it was 40°F I went to fire it up to trouble shoot the knock and it was gone.
It was a collapsed lifter that was full of air.

Later when I tore the engine apart I found an air bleeding lifter oil galley plug had been clogged up with a chunk of oil sludge. So the air could only escape from the lifter oil galley when it was some what mild out.

So cold oil does you no favors.

Now I will be able to use the inherent power of my 5,500w coolant heater, and/or my two 600w engine block heaters to help warm the oil.

This is what it looks like.
I think it will work because its slightly bigger than the heat exchanger that is in the radiator of a 6.5L diesel.
Both engines have oil pumps that pump a max free flow of around 20 to 25gpm.

http://ecomodder.com/forum/attachmen...1&d=1484152522

http://ecomodder.com/forum/attachmen...1&d=1484152522

It wasn't cheap, if I remember correctly this little deal was around $100.

How are you planning on plumbing this in? Are you planning on replacing your cooler with this heat exchanger?

Yes replace the air to oil heat exchanger with coolant to oil.
I probably will not have an air to oil cooler at all on this engine.
On my diesel I added an air to oil cooler on a valve that I open in summer and close during the cooler months.

I was just trying to find some quantification on how much this may help fuel economy. Its obviously one of those YMMV scenarios. For me, I do a lot of short runs. My commute is 7 miles, to do a lot of shopping its less than that. Warm up is super important. For others, it may not be.

Anyway, I did find this article about oil viscosity and fuel economy. It basically says the difference between 10W30 and 15W40 is 1% in fuel economy. No specifics of how things were tested were shared. This is probably considering the engine is already warmed up. Therefore, fuel economy before warming would be even larger, thus warming is more important.

Research Shows Oil Viscosity Affects Fuel Economy - Article - TruckingInfo.com

Found a bit more info. Here is a oil temp vs viscosity chart. If the lines are THAT close together at normal operating temperature (~90°C), then at colder temps they are quite a bit more drastic.

Image from: Oil Viscosity Explained

http://ecomodder.com/forum/attachmen...1&d=1484246738


Image from: https://www.quora.com/What-is-the-di...0-5w-30-10w-30

http://ecomodder.com/forum/attachmen...1&d=1484247257

Yeah I also drive about 6 or 7 miles to work each way.
I use 5w-40 just about year round.
For a summer road trip I will usually put in 15w-40 since it gets changed at the conclusion of the road trip or shortly after.

Just trying to quantify things still...

If the purple vertical line here represents a 1% increase in fuel economy (per the test linked above), then the blue vertical line has to represent around a 3.5% increase in fuel economy. That is only at 60C / 140F. As the temperature drops, the difference in viscosity increases to quite a bit more. Our cSt at operating temps is about 13. An increase of 5 reduces fuel economy by 1%. Obviously it can't be completely linear, but the cSt at 0C / 32F is over 1400 for 10W30 oil. So, I think its safe to say that heating the oil up must have some pretty decent fuel economy benefits.

http://ecomodder.com/forum/attachmen...1&d=1484247951

Stuff like this is why I'm so ga-ga for 0W30 oils these days. Even if we don't often put the low-temperature specs (-35°C, yow) to the test, they'll flow much better after cold-weather starts than 5W_ and 10W_ oils. Just imagine what that chart would look like if extended to include some real cold temperatures. ;)

The data sheet is not copy ,pasteableChevronTexaco RPM® SAE 15W-40 Heavy Duty Motor Oil
Viscosity cold crank

So, of course, this begs the question. What are DIY type ways we can use the coolant to heat up the engine oil?

This heat exchanger is about the best idea I have.
I have also seen sandwich type heat exchangers that stack on to where the oil filter attaches. But I have only seen those on 4 cylinder diesel engines.

Actually if I can find a oil filter heat exchanger that is big enough I would just use that instead. I would only have to run coolant lines, as opposed to oil and coolant lines.

I've actually been looking into those sandwich types as well. They aren't super common, but can be found. I think this is probably the easiest ways to do this mod, although there are many other ways.

Honda has used them on quite a few engines including the CRX HF, Civic VX, and Insight (as well as a few others). I went and checked this morning and sure enough, I have one slapped to the block on my Insight.

For others not familiar with these, in the picture the silver thing you see that the oil filter is screwed to is not the block, its a device that circulates coolant through it. Thus, as the oil is flowing through it, it gets heated up.

http://ecomodder.com/forum/attachmen...1&d=1484320667



So, I was like 'cool, I'll get one for my Prius'. Unfortunately, that won't really work. Honda uses a M20x1.5 thread on its oil filters. Toyota like many domestics I'd assume uses a 3/4"-16 thread. I searched ebay and was able to find one of these for a Tundra, but I haven't searched a ton. I assume that other manufacturers have similar parts, its just a matter of finding them. FYI if you're looking, they're typically referred to as an 'oil cooler' as they will cool the oil with the coolant when the oil gets warmer than the coolant. Thus, I believe its also used on the Integra and Prelude engines as well.

Here are a few more pictures of the Honda ones to give an idea of what they are and how they work. I'm really surprised we haven't talked about these before on EM. I searched and was only able to find one really old thread where it was mentioned, but not really discussed in any depth.

http://ecomodder.com/forum/attachmen...1&d=1484320996

http://ecomodder.com/forum/attachmen...1&d=1484320996

http://ecomodder.com/forum/attachmen...1&d=1484320996

Until the engine is running, or the oil is otherwise being made to flow, I don't see it heating a lot of the oil. If the engine is running, the oil will get warmed up rather quickly from the already pre-heated block as soon as it gets flowing.

You could flow hot coolant through your oil pan, similar to your idea of installing heater elements in the pan. But if/when they leak, your engine is in trouble.

Can you make the oil flow through a non-running engine somehow? Then the engine block is your heat exchanger.

Spinning the whole engine would waste too much power. Doubt you can spin the oil pump with it still attached to whatever drives it in the engine. So...an external pump with it's own pick-up tube, pumping oil up in to one of the rocker covers? Well...now we're just getting complicated...

Completely correct.

This is exactly what I thought, but apparently its not really the case. Oil Pan posted a bit ago that his oil pressure doesn't drop until significantly after the coolant is at operating temperature. Temperature testing would be very interesting to see how oil temp lags behind coolant temp.


Quite true, if you want to get beyond this point, it starts getting more complex. I do like the idea of flowing coolant through a heat exchanger in the oil pan. This gives us the opportunity to preheat the oil with the block heater, but we'd likely need an electric water pump. IMO this would be a lot easier than trying to flow oil without the engine running, but still not easy or cheap.

Of course, we can also use a pad heater on the oil pan to heat it up as well. But, that only works when you can plug in, and the heat exchanger works everywhere all the time.

That is a pretty cool find, Daox. I wonder if the main purpose is actually to cool the oil once up to temp, though. Engine wear/longevity is improved if you have a way to keep your 5W30, 5W20, and now 0W20 oils from getting too thin with a hot engine. In the earlier cars you mention, the VIIs of the time may have been one of the concerns driving this inclusion, as high heats are murder on them.

But since oil temps lag coolant temps during warmup, it is a nice way to get a little more heat into the oil sooner. Pretty slick. :thumbup:

You could pressurize the oil with a 12v gear pump. But I don't see any advantage to the expense and complexity involved.

The oil does heat up through the block but it also loses heat through the sheet metal on the oil pan.

I am planning to use the ehxsost from my diesel fired coolant heater (yet to be installed, got the parts gust have to finish the planning and will be out of town for 2more weeks). Problem is EGTs have been measured at 200°c witch is at or near flash point of the oil248°c.

It might not be lagging behind. The oil might be as hot as the coolant when the coolant gets up to temperature. The oil might continue to heat up past that point, and it's not until it hits a higher temp that the viscosity starts dropping off noticeably. The oil has no way to shed it's heat, except through the engine itself. If you add a coolant to oil heat exchanger, your oil might never get hot enough for the oil pressure to drop much.

Whether or not there is any benefit to your oil being heated past ~200f, I wouldn't know. The downside being that it can break down at higher temps or just not give as much lubrication from having too little oil pressure.

Rather than flow the coolant through the oil pan and risk all your coolant ending up in your oil, you could always flow it around the outside of the oil pan one way or another. Not as direct, but safer.

A small electric pump could circulate coolant off of the heater core hoses. Find one meant for circulating solar hot water.

It doesn't have hot coolant flowing all the time (or often enough), but you could run oil through the cooling line that goes through the radiator meant for cooling transmission fluid. If there's any way to make that work for what you're trying to do...

That is a distinct possibility. I would imagine since Honda put it on nearly every fuel efficient model, that it will help fuel economy in some way. Perhaps it does help, but it also hurts? It just happen to help more than it hurts... Interesting ideas. :)

Do these Honda engines have oil squirters for cooling the pistons? They might be necessary on lean-burn engines, not just on high-performance ones. If so, it might be necessary to force-cool the oil to absorb all that heat the oil has taken in, lest it break down or thin out too much.

Those sandwich plates are designed to allow the oil to be cooled with the coolant, not heated. Good ones are thermostatic and won't flow any coolant until everything is up to temp.

If you check the link below, its called an oil warmer for the Insight:

https://www.hondapartsnow.com/genuin...2-phm-e00.html

The oil runs hotter than the coolant.

I thought it was pretty settled that the coolant warms up faster than the oil. Water is a much better thermal conductor than oil, and it flows through higher-temperature parts of the engine than the oil.

So that heat exchanger should get to function as both an oil warmer and an oil cooler, just at different stages. :)

(I'll welcome corrections if wrong.)

This is what Google showed me when I looked for an outlet oil warmer for the 2000 Civic HX:

Strangely, it did not show the air freshener on the page of Dorman products.

I was searching for block heaters for my wife's Jetta, and discovered along the way that that heat exchanger is called an "oil cooler" when installed on watercooled VWs: VW Oil Cooler ::Oil Cooler: Many VW 4 Cyl. water cooled, Gas or Diesel, 83-05 - sku:15359 - - PartsPlaceInc.com :)

On Cummins the oil cooler /herter is between the pump and filter. Inside the block right next to the block heater. There is no bypass on the heater/ cooler. There is a pressure bypass that bypasses the filter when the pressure is too high, from excessive viscosity restricting the flow through the filter, or a dirty filter.
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The oil pan transmits heat to the oil from the block,I'll be it minimal. Otherwise the coolent based blockheater would not improve cold starting by reducing the viscosity enough to allow crainking. But I want more....to ease starting and improve MPG.

That would be easy to fix.

There was an artic cold weather kit for the hmmwv that took coolant heater exhaust and used it to warm the bottom of the oil pan. I always figured it only heated the oil on one side only so the exhaust doesn't over cook the oil.

So, it seems as though if you have a Honda, you can pick up an oil warmer/cooler VERY inexpensively. They sell on ebay for around $10 used. Since its not a wearable item that sounds like an amazing deal. However, the ones for $10 are made for sport bikes. I'm not 100% sure that the housing is large enough for car/truck oil filters. However, for more money one can find one specifically used on a car engine. If you do try one of the bike ones, just make sure it is the type that allows you to mount a filter on the end. Some of them are capped off on the ends.

One end will always look like this:
http://ecomodder.com/forum/attachmen...1&d=1484406031

The other end MUST look like this:
http://ecomodder.com/forum/attachmen...1&d=1484406031



If the end looks like this, you will have no place to mount your filter:
http://ecomodder.com/forum/attachmen...1&d=1484406031



Also, a lot of these auctions do not come with the bolt that holds the warmer/cooler in place and allows mounting of your oil filter. So, you will either need to make sure that your item comes with it, or find one separately. You'll also need an o-ring or seal so it seals to the block. The bolts look like this:

http://ecomodder.com/forum/attachmen...1&d=1484406303

http://ecomodder.com/forum/attachmen...1&d=1484406303



For those of us who do not own a Honda, or other make that uses M20x1.5 threads for the oil filter, what are we to do? We have a few options. So far I've found these vehicles that use similar oil warmer/coolers:

Early 2000 to mid 2000 Jaguars (unknown thread).

Numerous Mazdas have these, the Miata, 3, 5, etc. (unknown thread).

GM & Chevy have one that I found for the Camero / Corvette.

Toyota Tundra 4.7L has a 3/4-16 thread and probably uses larger filters suitable for larger engines. These also cost a bit more. Cheapest I found was $38 shipped.

By far the most prevalent was the VW / Audi oil coolers. They have a few vehicles with oil coolers on them with 3/4-16 threads. Here is what it looks like. Prices on ebay varied quite a bit for these. Again watch so you get the bolt and the seal with it or you'll have to buy it separate.

http://ecomodder.com/forum/attachmen...1&d=1484406952


Yamaha, Suzuki, Triumph, and Kawasaki bikes also have oil coolers. I am lead to believe they use the M20x1.5 thread as they seem to have interchangeable oil filters with Honda bikes. I haven't dug real deep into this though.

So, those are the warmer / cooolers I found. I stopped searching after prices hit about $50. I think there are plenty of choices, and if the motorcycle warmers fit a car they are really cheap.

Of course, one alternative is to buy a cooler and make your own bolt for it. In that case, it almost doesn't matter what cooler you go with as long as it fits up and seals to your block.

I think this mod is really a great idea for those of us who make a lot of shorter trips.

Those are pretty much never found on domestic cars.

I did some more digging just to see how oil temperature follows coolant temperature. I found these charts posted by members of a BMW forum. As I anticipated, oil temperature lags coolant temperature pretty drastically as Oil Pan's pressure information suggested. Of course, I'm not sure where this oil temperature sensor is located. I would guess that it is inside the oil pump. So, the oil wouldn't have time to be heated by the engine block much. Once it has been pumped through the engine it will obviously pick up heat. However, without a temperature sensor in the return flow of the oil we have no way of really knowing. But, we really want to be pulling warm oil to begin with. Its not just the friction of the engine that is reduced with lower viscosity oil, its also the work that the oil pump has to do as well. Pumping thicker oil and thus having higher oil pressure requires more power from the engine.

These charts show two different trips. The first one is a city drive he did, the second one shows a trip to his work with some highway driving. From the charts you can see that coolant temperature starts around 30C / 86F, so this is obviously a summer drive. Coolant temp hits ~100C after only about 3 minutes of driving. How long does it take the oil to warm up to that temperature? Nearly 20 minutes! By that time, my car would have already been sitting in my work parking lot for about 5 mintues.

http://ecomodder.com/forum/attachmen...1&d=1484587436

http://ecomodder.com/forum/attachmen...1&d=1484587436

Yes 20 minute oil warm up time.
I'm pretty sure that there was an old post on here saying pretty much exactly that.

I'd like to do some testing with the Insight since it already has a sandwich plate coolant warmer installed on it. All I would need to do is crimp the line to see a with/without scenario to see how effective it really is.

Of course, I would need to add a sensor for measuring the coolant temperature. I think something like this thermometer mounted in a modified oil pan drain plug would work nicely. Or, would it be good enough to just strap the sensor right to the bottom of the oil pan and tape some insulation around it? What do you guys think?

Sticking a thermoresistor or thermocouple to the pan under some HVAC tape would work just fine.

http://i.imgur.com/4MbwTd7.jpg
The engine in my track car has one, (as-stock) its plumbed into the hot side radiator hose behind the thermostat (so it only receives hot water after the engine is up to temp.) I've considered either dual-stacking it with a thermostat oil cooler, or plumbing it in differently so it would receive cooler coolant. However, just keeping the coolant temperature low overall by keeping the cooling system efficient seems to do the job.

I also took one and installed it on my diesel, but never got around to plumbing it in. I was going to put in in-line with the heater matrix so it would help heat up faster.

Toyota uses m20x1.5 thread in the rest of the world, I can't imagine them changing *that* on US-sold cars..