Engine oil Thermostat

Engine, Transmission and related drivetrain.
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Byron510
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Engine oil Thermostat

Post by Byron510 »

Have any of you installed an engine oil thermostat with the use of a remote oil cooler?

I’m running a water to oil cooler, and my engine oil temp is way too low. As the coolant system never runs over 180, and is often lower, I’d like to address this.

Finding the optimum oil temp seems to be a topic of great debate, however I gathered that between 220 and 240 is the range you should be shooting for. And that’s a lot higher than my engine has seen in a long time.

I have two questions about the engine cooler thermostats;

- Many brands don’t list the temp which they are set for - just “adjust to the optimum oil temperature”...

- what is a good brand of oil thermostat to use?

Any thoughts you guys have, would be greatly appreciated.

Thanks.
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funwithmonkeys
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Re: Engine oil Thermostat

Post by funwithmonkeys »

I was thinking about this also Byron. The highest temp my oil has seen in the last 4 years it 210. Most times it is below 190...and that is my inlet to the cooler closed.
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Re: Engine oil Thermostat

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I think you may be really concerned when I tell you that on my last drive - in very good weather - the oil temp reached a max of 180. In fact, it spent the first 4 hours never above 160....
Let’s just admit that the 13 plate Nascar style water to oil cooler is quite efficient! Because the oil is exactly what the water temp is! Always.

So if anyone out there has some experience, and would be willing to share, I’d love to hear from you before I fly blindly into this one.

Thanks.

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datzenmike
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Re: Engine oil Thermostat

Post by datzenmike »

I have a 280zx oil filter adapter but ran hoses out in front of the rad and used a Ford 350 oil cooler. If it wasn't so much bother I would take it back off. The highest my oil temperature has ever gone was low 90s (195F) They are simply not needed. Gauge starts reading at 60 (140F) and on average runs 70s (160F) and will bump 80 (175F) The plan was to augment the cooling system.

Sometime I will just gear clamp a 1/2" copper U pipe and remove the cooler itself. Even the hoses will shed some heat.

One other advantage of the oil/water transfer is the oil warms up faster. Oil temp is always WAY behind the coolant temperature. I would say it takes at least 20 minutes of driving just to get to 140F (60C) I just don't like the idea of having oil and water so close together.
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Tedman
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Re: Engine oil Thermostat

Post by Tedman »

My experience with oil thermostats has been exclusively with Earls brand and with oil-to-air coolers. I tested my thermostat and it started to open at 180F. After I read your post I looked in the Pegasus Racing catalog and both sandwich and remote oil cooler thermostats that they sell also open at 180F. That makes me think that the oil thermostat might be primarily to protect the cooler from high oil pressures when the oil is cold, rather than for regulating oil temp like the radiator thermostat. If it was meant for regulating the oil temp, the opening temp would be higher and closer to optimum oil temp. In reality, the 180F opening is likely a compromise between cooler protection and oil warmup, and the running oil temp is meant to be controlled ultimately by the cooler size. Seems to me your oil-to-water cooler should warm the oil quicker than an unregulated oil-to-air cooler and keep it closer to water temperature, *if sized properly*. Your cooler sounds like it might be too efficient for your conditions.
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Re: Engine oil Thermostat

Post by Byron510 »

You are correct on more that one front. The rad and oil cooler are both too efficient, and not matched - apparently.

Dealing with the coolant temp alone - it should be at 180, min, under operation. This is where I need to start over the winter.

However, even if the water temp issue is solved, this may not bring the oil temp up because the heat exchanger is on the cool tank on the rad...

I appreciate you chiming in, but I still likely need a solution in the form of an oil thermostat that will actually regulate oil temp. I’d like to see it up at 210-220 - unless someone and tell me that I’m off course on this :-) There must be a solution.

Thanks.

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JordanTr
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Re: Engine oil Thermostat

Post by JordanTr »

You should add a turbo or 2. That ought to add some heat and put both your rad and oil cooler sizing pretty close!

Perhaps a blank off plate for part of the rad could be a good solution for now.

I’d have to review the FSM for the RB engines and see if the water-oil cooler in the OEM config is set up with incoming or outgoing water. Perhaps it is outgoing water since it is mostly controlled that way and won’t be aggressively cool.
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Re: Engine oil Thermostat

Post by Byron510 »

I see that Summit Racing sells the Improved Racing thermostats that are available in 145,165,185,205 and 215 temps.

http://www.improvedracing.com/oil-therm ... p-212.html

So I have to revert to my initial question - what is a good oil operating temp? I was told years ago that the oil temp should be maintained about 20 degrees higher than the engine coolant temp, but I can’t find any good literature to back that statement up.


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datzenmike
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Re: Engine oil Thermostat

Post by datzenmike »

Looks like 220 to 260F for ordinary oil. This boils off any water contaminants and thins the oil to the maker's specs and improves the mileage. Like I said I only once got to almost 200F climbing Mt Washington at full throttle in 3rd and 4th. Engine temp was at over 3/4. I don't think anything but a race car application even needs one. Oil water is good for warming the oil faster.

Next year I'll remove the cooler and see what the difference is. Maybe the cooler is too big?
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Byron510
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Re: Engine oil Thermostat

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datzenmike wrote: 26 Oct 2020 07:55 Looks like 220 to 260F for ordinary oil. This boils off any water contaminants and thins the oil to the maker's specs and improves the mileage. Like I said I only once got to almost 200F climbing Mt Washington at full throttle in 3rd and 4th. Engine temp was at over 3/4. I don't think anything but a race car application even needs one. Oil water is good for warming the oil faster.

Next year I'll remove the cooler and see what the difference is. Maybe the cooler is too big?
Hi Mike,

I appreciate your input.
I have seen temps north of 250 in most of my LZ22's, which have all been relatively mild engines (10:1 C/R, roughly 280 deg cams) on a continuous flat road, highway speeds around 70 MPH (near 4K RPM, continuous). This is enough to already drop the oil pressure 5-15 lbs (in the same engines) depending on the type of oil in use.
I built a new rad built from scratch for The Bronze in 2009, and I incorporated a heat exchanger (oil cooler) into that build to bring those summer oil temps down to 220-230 degree range, which was the goal. Here's the link to that part of my build, starting about halfway down the page;

viewtopic.php?f=27&t=530&start=645

Rad installation halfway down this page;

viewtopic.php?f=27&t=530&start=675

And I didn't hook up the heat exchanger until the following year noted here;

viewtopic.php?f=27&t=530&start=690

On the cooling side - man it's never been better on any 510 I've ever owned. Even now - 10 years later it’s still better that it needs to be. I did a good test this summer - Blasting up out of Ashcroft towards Logan Lake is a good steep grade. And it was a hot day; the car was 'well driven' for 15 minutes up that pass, and the coolant temp didn't even tick over 180. The rad wasn’t even trying. Same result again for the Princeton Mine hill about two hours later on the same drive. It’s a steep grade and I was just pegged in 4th for 5 minutes (because I didn’t have the power to hold 5th on this grade!). the rad does very well – no complaints.

Regarding the heat exchanger; Mike, I will agree with you - I was shooting for the benefits of faster oil warming, and more consistent oil temps. Well, I nailed the consistent oil temps... albeit way too low! The rad is so efficient that it has completely soaked out any engine and oil heat without blinking an eye! In other words – I’ve gone too far.
So I got on the phone today. Turns out Mishimoto is not as Japanese as I thought the company might be. Based in Delaware, the sales guy informed me that ‘Mishimoto’ was the owner cat… Jesus, I didn’t see that coming! Honestly, I was informed the name was used early on in the production and engineering of their products and before they knew it -the name was stuck! That’s a funny story, I love that kind of thing. And yes, their product is actually made right in the US of A, looks like it’ll do the trick.
Anyways, the tech guy was super helpful – knew his product inside out. I purchased the standard inline oil thermostat unit – which comes with a 180-degree thermostat and -10 fittings which is what I needed. Then I bought the optional 200-degree thermostat (and a spare at $14 each), as they were not available “installed”. The whole package is still a very good deal at $192 USD shipped. As a bonus and the deal maker, they’d ship to me USPS, which is important for us igloo lovin’, sled dogging Canadian types – FedEx and UPS use the border as a license to print money and generally screw you over. Canada Post plays fair; I pay my reasonable duty and I’m outta there. It just takes a few more days, I can live with that.
Here’s the unit I bought.

https://www.mishimoto.com/mishimoto-in- ... ostat.html

And a 200-degree thermostat is available;

https://www.mishimoto.com/mishimoto-san ... -200f.html

So, I guess I’ll be doing seem more plumbing in my near future, placing the thermostat somewhere between the remote adaptor and the heat exchanger to resemble something like the diagram below.
pic_5_oil_cooler_flow_detailed.jpg
pic_5_oil_cooler_flow_detailed.jpg (49.57 KiB) Viewed 780 times
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JordanTr
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Re: Engine oil Thermostat

Post by JordanTr »

Congrats! It sounds like you found a great solution. It would be interesting now to know how much flow will actually be diverted through the cooler but that would be tough to determine.
One thing you could consider is putting your filter first in the system train. Oil will filter best when hot and it’ll protect your fancy thermostat and cooler from getting fouled if anything ever did let go in the engine.
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Re: Engine oil Thermostat

Post by Byron510 »

Thanks Jordan for your thoughts.

So there is a 5% flow through the cooler at all times, so technically there is a max of 95% bypass when cold.
This engineering feature is there to eliminate air pockets and also back pressure in the wrong dire action. The second fact I hadn’t even considered myself.

The position of the filter is of some major debate. I too, though as you - the filter should be first there by keeping everything downstream clean. However as it was explained to me - debris can collect anywhere, so what do you want to protect? You’ll find that nearly any engine builder will put the filter last in line right before the engine as the engine. I know, I had to think about this for a while myself.

Oddly, if you look online - there are nice diagrams of the plumbing both ways. It was on the advise of a could engine builders that I put the filter right before the oil returns to the engine.

Another project to play with over the winter. If finances can bear it, maybe done in conjunction with a bottom end motor rebuild as well.

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Tedman
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Re: Engine oil Thermostat

Post by Tedman »

Another nice thermostat feature to have is rebuild-ability. If you scatter your motor, at least you won't need to buy another thermostat. Just take it apart, clean it out and reuse. Hopefully that MIshimoto unit does the trick. Let us know how it works out.
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Re: Engine oil Thermostat

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Tedman wrote: 27 Oct 2020 14:01 Another nice thermostat feature to have is rebuild-ability. If you scatter your motor, at least you won't need to buy another thermostat. Just take it apart, clean it out and reuse. Hopefully that MIshimoto unit does the trick. Let us know how it works out.
Funny you mention the ability to disassemble and clean. I ask this same question and was told this is no problem with the design. It’s the same process as changing the thermostat, which is apparently a very quick job.

The part is now in the mail, I got the confirmation number yesterday. I suspect 10 days delivery.
I’ll keep you all posted.

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Re: Engine oil Thermostat

Post by funwithmonkeys »

I'm watching to see how it goes Byron. My oil has not been past 215 since I put the cooler in. That was in the summer at 30+c with the inlet closed. It may be a good solution for me to get the oil into a better range.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?
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