Oil Cooling - An In-Depth Look

[Tor]

Originally Posted by Calvin27

Anyways, for those that run an oil cooler, how to do you do an oil change? Do you just accept that the change will retain about 600ml of the old stuff or is there actually a way to drain it?

Most accept the remaining 600 ml. There is 900 ml more old oil in the engine anyway as 5.4 liter oil is required for a normal oil change, but it takes 6.3 liter to dry fill the engine. So it's normal for some old oil to remain in the engine.

If you drive the car under conditions where an oil cooler is required, you may want to consider to change the oil twice as often as well. That will mitigate it somewhat.

Second, without a thermostat, you could potentially do the easy solution of a drop in barrier to block the radiator and/or simply warm the car up before driving. Also what about a simple manual operated valve - this works because you know when you are gonig to be tracking or spirited driving for a prolonged period before you drive.

I see no good reason not to run a thermostat. The cost of a thermostat is negligible. However, even with a thermostat, you might want to consider blocking off your oil cooler in certain situations.

The easy solution looks like this:


At low temperatures, the water cooler will have plenty of cooling even with 1/3 of the air intake blocked off.

Here is a log warming the engine up at 0 deg ambient (40 f) with the cooler blocked off:


The vertical lines are 5, 7, 10 and 14 mins.

1) The oil cooler has no function without air flow, so it's very effective to block it off - just as effective as disconnecting it all together.

2) The car heats up just as fast as with no oil cooler installed.

Here is a log with doing a few pulls to 180 km/h (111 mph) on autobahn and then leaving the autobahn and driving normally on back roads:


Previously, I had the problem to get the temperature properly up when driving the car on autobahn at ambient temperatures of 5 c (40 f) or less. And that the temperature would drop quite a lot once getting off the gas. With "properly" and "drop a lot", I mean I would have temperatures of low 70's deg c (160 f).

Here you see the oil temperature remains fairly constant and that coolant temperature is unaffected. Obviosly, you would want to do your own readings to decide when it's appropriate to block off the cooler and that it doesn't have any adverse effects.

Third, what exactly is the mechanism in the thermostats for air based cooling?

Here in lies the problem why you still need to block the cooler even with a thermostat installed:

[ame="https://www.youtube.com/watch?v=l6Z2q-ttyOA"]How does it work? - Mocal thermostatic sandwich plate - YouTube[/ame]

[JazzleSAURUS]

Originally Posted by weederr33

I have all the ingredients for the oem kit, but I failed myself by nearly stripping the block off bolt you use under the engine. And the throttle body route is out of the question.

This is because of your supercharger kit using/blocking the throttle body area?

Are you trying to offload the parts? I only really need the heat exchanger and the longer bolt nut thing.

[weederr33]

Originally Posted by JazzleSAURUS

This is because of your supercharger kit using/blocking the throttle body area?

Are you trying to offload the parts? I only really need the heat exchanger and the longer bolt nut thing.

I could get to the throttle body, but it would be a lot of trouble. But yes, installing the Cosworth kit requires you block off the 2 TB locations.

[JazzleSAURUS]

Originally Posted by weederr33

I could get to the throttle body, but it would be a lot of trouble. But yes, installing the Cosworth kit requires you block off the 2 TB locations.

Got it makes perfect sense. If you're trying to ditch those two parts, shoot me a message with what you're looking for, I'm happy to entertain the idea!

[gtengr]

Originally Posted by Calvin27

Also what about a simple manual operated valve - this works because you know when you are gonig to be tracking or spirited driving for a prolonged period before you drive.

This seems like the way to go. Anyone ever tried a setup like this?

[Ultramaroon]

Originally Posted by gtengr

This seems like the way to go. Anyone ever tried a setup like this?

Working on it. Eric knows all about these.

[Calvin27]

I would think that bypassing at the sandwich plate would be better. Haven't had a look at the sandwich plate design to know if it's possible though.

[Ultramaroon]

Better or worse depends on the requirements. Mine is thermostatic control of oil temp to below 200 F in all conditions.

[200hp/tonne]

Originally Posted by VeloxEric

If it makes you feel safer, run a bit thicker oil but with thicker oil, comes increased engine wear at cooler temperatures and increased heat into the oil through more friction and less flow (flow and pressure are inverse, as you increase pressure, you decrease flow). Above this temperature, we would recommend increasing the hot temperature weight to ensure sufficient oil pressure. Due to each engine having different optimum operating conditions, we cannot recommend a pressure/RPM to shoot for.

Please correct me if i am wrong, but i thought positive displacement pumps like the FA20 oil pump create flow, and what we see as pressure is the back pressure from the flow passing through restrictions. Also, hydrodynamic bearings in the engine need the right amount of oil flow and right amount of oil viscocity, right? So it follows naturally that at high temps (back)pressure will drop significantly due to a viscosity change, but volumetric flow will not. So as long as the flow and viscosity are within spec for the bearings why should we care about pressure? i have seen so many threads and posts freaking out about low pressures at only above average temperatures and then condemning the FA20 engine and its choice of 0W20. As long as my brand/formulation of 0W20 is stable at the temps that i see on my car, why should anything else matter?

[7 skulls]

https://forums.nasioc.com/forums/sho....php?t=2714154

Lots of good info. on the thread above. With 5W20 as the viscosity drops with temperature (as the graph shows at 220F / 7.5 cSt) the oil pump seems to fall off the back end of its curve, losing pressure and flow rate due to slip.

[VerusEric]

Originally Posted by 200hp/tonne

Please correct me if i am wrong, but i thought positive displacement pumps like the FA20 oil pump create flow, and what we see as pressure is the back pressure from the flow passing through restrictions. Also, hydrodynamic bearings in the engine need the right amount of oil flow and right amount of oil viscocity, right? So it follows naturally that at high temps (back)pressure will drop significantly due to a viscosity change, but volumetric flow will not. So as long as the flow and viscosity are within spec for the bearings why should we care about pressure? i have seen so many threads and posts freaking out about low pressures at only above average temperatures and then condemning the FA20 engine and its choice of 0W20. As long as my brand/formulation of 0W20 is stable at the temps that i see on my car, why should anything else matter?

This isn't my area of expertise but I'll do what I can to answer as much of it as I can.

It is a positive displacement pump and bearings do need the right amount of oil viscosity. At higher temperatures, flow will increase and pressure will decrease, correct.

Pressure is a measurement of the oil's viscosity, that is why we worry about pressure. I'm not sure what sensor measures viscosity, or if there is one, but our engines certainly do not have a viscosity sensor so what we have to work with is pressure. Pressure dropping is a sign of viscosity decreasing.

I completely agree that people over-exaggerate about oil temperature. If you are pushing your oil temperatures over 230-240 degrees, you are driving aggressively. The owners manual even states to run thicker oils as you drive more aggressively, and that is to ensure proper viscosity at these higher temperatures.

The NASIOC thread posted above, which I skimmed, seems to be a pretty thorough thread on oils. I started this thread to discuss different ways of cooling oil, which is what I would say I know more about than actual oil properties in the engine. Hope I helped answer some of your questions though.

Thanks,
Eric

[gtengr]

Originally Posted by Ultramaroon

Working on it. Eric knows all about these.

any updates?

[Ultramaroon]

Originally Posted by gtengr

any updates?

Getting closer. Routing is a bit of a challenge but I think I've found some adapters that will fit the bill. I'll do a full write-up including results. Goal is to get it functional in time for the first Cascade Sports Car Club HPDE class this May.

[nikitopo]

Originally Posted by Tor

Next, living in the country (Germany) with probably the highest failure rate of FA20 engines I would strongly advise against running oil temperatures above 100-110 deg C (212-230 f) on a daily basis. The reason for that is simply that the oil degrades much faster due to thermal breakdown - at a rate twice as fast for every added 10 deg C (18 f).

Almost every single reported engine failure (non-modified NA engines) that we have here occurred because people drive their cars regularly above 200 km/h (125 mph) on speed unrestricted Autobahn while sticking to the factory specified oil change intervals of 15.000 km (9320 miles).

I agree with Tor. I had once on the autobahn oil temperatures up to 132 deg C. Outside temperature was around 15 deg C. This oil temperature was achieved after 5-10 minutes while using 5th gear (5-7k rpm) . With 6th gear (lower rpms) things are better. I am sure that many owners don't have an idea about this, because they are not monitoring the car.

Personally, I don't have an oil cooler because there are some side effects like the remaining old oil during the changes. I don't use either the forester solution, because I don't think to be very effective. I just change the oil much sooner (less than 5.000 km), since I don't drive the car too much. Another suggestion is to use 5W30 oil. Subaru Germany suggests this grade. I'm not sure if Toyota Germany uses a 0W20 oil.