How hot is too hot for motor oil

[edyvw]

Yes, of course, it's more or less the same on the GTI. Target temperature (for both coolant and oil? not sure, though I do reach 110°C on hot summer days) when cruising is somewhere at 110°C (which obviously the engine won't reach in the colder season), while target temp at full load is somewhere at or slightly above 80°C (which again obviously it'll never reach even in winter). These targets can be altered via some aftermarket software, giving some additional margin and the engine will reach elevated temps (e.g. 122°C oil like the OP) somewhat later. However, I'd guess it's just a shorter time span, two minutes or so, until it's at the same elevated level. I doubt this is a full substitute for additional cooling capacity.

I still would do both coolant mix (as it's almost for free) and 5W-30/504 00 first (he'd want to change oil soon anyway).

You're right btw., thicker oil will increase drag and thus increase temps by itself. One more reason not to overdo. On a side note, coolant on the GTI is near 10 liters, if I'm not wrong, and engine oil capacity is 6.6 liters total, while oil change volume is 5.7 l (almost one liter is remaining somewhere in the pan), which isn't skimpily for a 2.0 4-pot. Manual gearbox is 2.3 liter.

BMW N51/52/53/54/55 works differently from VW. They also work differently between them. N51/52/53 one can't easily manipulate DME. On N54/55 one can even without a tune.
VW has a regular, belt-driven pump while BMW's of that generation have an electric pump. DME in BMW will run those engines as hot as possible during the cruise, around 113c. It has 4 different modes. At the track, DME will try to target the temperature to 80c. That is even without any tune. So, the fluid/fluid heat exchanger is pretty effective, but on track, it is easily overwhelmed especially if a bit of altitude is involved. ON BMW at least adding oil cooler is as easy as it gets bcs. oil filter housing is the same for all those engines and N20. So one just has to add a thermostat that has ports and put cooler in place. All chassis are kind of ready to go. Not sure how will that work on VW. As I can see it is bit different as there is no thermostat housing. If OP goes the cooler route, the thermostat is a must. In my case, added cooler did not affect at all cold performance. The thermostat opens at 110c.
On VW system is more conservative, so I do not think it has so many coolant temperature targets.
But, the oil sump on GTI, which we forgot to mention, is super big. It actually takes more oil than my Toyota with 3.5 V6 which is 6.4qt. That is definitely a plus!

 

[2EHA]

Also, 0W-anything is probably too thin for real world protection under those temps. I'd suggest an HTHS of 3.8 with those temps. That will likely require a stable oil that is shear resistant and a 5W-something.

opinion discarded

 

[930.engineering]

Yes, I know about the electric pump on most BMW engines. Not sure on the number of temp targets on the EA888 3G, but I'd bet it's more than just two. The thermostat is electronically controlled, as well as the oil pump.

 

[edyvw]

Yes, I know about the electric pump on most BMW engines. Not sure on the number of temp targets on the EA888 3G, but I'd bet it's more than just two. The thermostat is electronically controlled, as well as the oil pump.

So does ECU reacts to "track-like" driving in GTI and lowers temperatures? I did not venture on VW forums for a long time as my Tiguan is built like a tank
I know on Tiguan I can shoot up coolant temperature in no time just driving bit more aggressively on Pikes Peak.

 

[Davejam]

a/ if 100C is the coolant target temp, then the system is keeping up with demand. Running the heat might not do a thing, though does technically shed more heat. If 100C is the target, the rest of the system will just work less hard to shed heat while the driver cooks.

b/ if the coolant is 100C while the oil is significantly hotter, then an issue is transferring heat from oil to coolant fast enough. Things that could help -- cooler coolant, more oil or coolant flow in the exchanger, larger heat exchanger. My oil/coolant heat exchanger is only about the size of my fist. I don't know that either altering the mixture or running the heat would affect the transfer of heat from oil to coolant.

This is a good way to think of it.

But yes in scenario B/ adjusting the mixture could improve the heat transfer, by ~15% going from 50/50 --> 10/90.
What that translates to in actual temperature is hard to say, but should be significant/noticeable.
And regardless of the oil cooler there is still an interaction betweeen coolant and oil through the engine.

I would think scenario C/ is most likely where both oil and coolant temperatures are exceeding design...in which case the 10/90 helps on both ends...it will cool off the engine and oil better but also be able to dissapate that heat through the radiator.

Running the heat seems insane to me, but its summertime in FL for me.

 

[tom in boise]

Just to add information, I am not allowed to add additional oil coolers or radiators in the class that I am running in (SCCA Street classes). If I perform other mods that push me into a higher mod class, then I could add additional cooling.

Speeds are probably 30-60mph for the autocross runs and 45-100mph for the track cross and hill climb runs.

This car is equipped with the 6 speed Manual transmission, so no DSG to worry about cooling.

I have some telemetry information available so I will review the oil temps as seen by the ECU during my next event, if I think of it.

I have a case of M1 ESP 5W-30 on the way.

 

[edyvw]

This is a good way to think of it.

But yes in scenario B/ adjusting the mixture could improve the heat transfer, by ~15% going from 50/50 --> 10/90.
What that translates to in actual temperature is hard to say, but should be significant/noticeable.
And regardless of the oil cooler there is still an interaction betweeen coolant and oil through the engine.

I would think scenario C/ is most likely where both oil and coolant temperatures are exceeding design...in which case the 10/90 helps on both ends...it will cool off the engine and oil better but also be able to dissapate that heat through the radiator.

Running the heat seems insane to me, but its summertime in FL for me.

I ran the heater at 90f here. I just point vents outside and close central ones.
It helps more than diluting coolant (which should be done regardless).

 

[edyvw]

Just to add information, I am not allowed to add additional oil coolers or radiators in the class that I am running in (SCCA Street classes). If I perform other mods that push me into a higher mod class, then I could add additional cooling.

Speeds are probably 30-60mph for the autocross runs and 45-100mph for the track cross and hill climb runs.

This car is equipped with the 6 speed Manual transmission, so no DSG to worry about cooling.

I have some telemetry information available so I will review the oil temps as seen by the ECU during my next event, if I think of it.

I have a case of M1 ESP 5W-30 on the way.

OK, this clarifies things.
Run heat, dilute coolant. Run heat if you can evacuate heat properly out of the vehicle. So basically, you are running now an additional cooler without breaking rules.
Can you take out any parts? Like can you take out cowlings to improve under the hood heat dissipation?

 

[Craig in Canada]

But yes in scenario B/ adjusting the mixture could improve the heat transfer, by ~15% going from 50/50 --> 10/90.
What that translates to in actual temperature is hard to say, but should be significant/noticeable.
And regardless of the oil cooler there is still an interaction betweeen coolant and oil through the engine.

It's worth a try, and costs nothing, but I'm not so certain that changing the mixture will improve heat TRANSFER between the two fluids. If there's not enough metal or "contact" to get the job done - probably not. If there's not enough flow of coolant, then I expect it would (since the same volume of coolant in the exchanger has a higher specific heat capacity when the mixture contains a higher proportion of water).

I would be interested in the outcome no matter what!

 

[edyvw]

It's worth a try, and costs nothing, but I'm not so certain that changing the mixture will improve heat TRANSFER between the two fluids. If there's not enough metal or "contact" to get the job done - probably not. If there's not enough flow of coolant, then I expect it would (since the same volume of coolant in the exchanger has a higher specific heat capacity when the mixture contains a higher proportion of water).

I would be interested in the outcome no matter what!

The coolant will transfer heat faster. If the coolant runs cooler oil will transfer more heat to the coolant. The engine has a fluid/fluid heat transfer box.

 

[930.engineering]

So does ECU reacts to "track-like" driving in GTI and lowers temperatures? I did not venture on VW forums for a long time as my Tiguan is built like a tank
I know on Tiguan I can shoot up coolant temperature in no time just driving bit more aggressively on Pikes Peak.

To be honest, I have no idea if or how the ECU is able to detect tracking. At least it notices environmental/air, coolant and oil temps, load and revs. The GTI should be able to better compete with higher temps since it's light weight and got a comparatively strong engine (for its weight) with comparatively solid coolant and oil sump capacity. At least this is my impression.

From Volkswagen Self-Study Programme 522 - The 2.0 TSI engine of the 162/169 kW 2012 GTI - Design and function > chapter cooling system, pages 37 and 39:

If the engine runs with low stress load and speed (partial load range), the rule thermogestion the coolant temperature to 107°C. The total power of the radiator is not required, the rotary valve 1 closes temporarily driving towards the main water radiator. If the temperature exceeds this threshold, driving with the main water heater is reopened. It follows a succession of opening and closing to maintain the temperature of 107°C as constant as possible.
When the load and speed increase, coolant temperature is lowered to 85°C (full load range) for complete opening of the pipe with the main water radiator.
Strategy in degraded mode If the temperature in the rotary distributors module exceeds 113°C, the thermostat for degraded mode opens a bypass towards the main water radiator. Due to this measure in the construction, continued operation of the vehicle in case of default of the rotary distributors module is only possible with restrictions. If the engine computer receives no feedback signal of position of the temperature control actuator N493 motor, it controls the rotary distributor to ensure maximum cooling of the engine, independently of the load and temperature of the momentary engine.

Thresholds might be slightly different on the 2018+ Mk7.5 GTI, though it should be overall the same. So I was't too far off with "somewhere at 110°C" (for partial load range) and "somewhere at or slightly above 80°C" (full load). Again, "target" doesn't necessarily mean coolant is actually hitting these exact values (ever). This SSP is describing just two target temps though, but I wouldn't take it toooo literally, as there are more errors in this SSP (such as main bearing diameter, number of counterweights etc.).

Btw, I wouldn't go any further than running 75/25 water/G13 mixture. He should notice the difference to stock 50/50 already.

 

[tom in boise]

OK, this clarifies things.
Run heat, dilute coolant. Run heat if you can evacuate heat properly out of the vehicle. So basically, you are running now an additional cooler without breaking rules.
Can you take out any parts? Like can you take out cowlings to improve under the hood heat dissipation?

I can only remove parts not held by fasteners, if that is clear. So if a cowling is snapped into place, it could come out. Held in by screws, it has to stay. Funky rules but they are what they are.

I appreciate all the good advise.

 

[Cujet]

opinion discarded

Good idea. No experience here,
Former race marine engine developer
Former Ford turbo camshaft development team engineer
Former Ford Motorsport race team tech and engineer
Former Porsche race team tech
Former high end vintage race car tech
[sarc]Not once have we noticed the pattern that typical 0W oils shear more rapidly than oils with a more viscous base stock and fewer VII's and pour point depressants. [sarc]

Suggest a quality "uber" 0W oil with a 3.8 HTHS that won't shear and I'll try it. Otherwise I'll go with known performers. A good one is M1, 5W-40 TDT. Redline and Am make some great ones. Of course, while I'm rambling on, the OP is making 200HP and our engines were making 700+ with 20% less displacement.

 

[edyvw]

Good idea. No experience here,
Former race marine engine developer
Former Ford turbo camshaft development team engineer
Former Ford Motorsport race team tech and engineer
Former Porsche race team tech
Former high end vintage race car tech
[sarc]Not once have we noticed the pattern that typical 0W oils shear more rapidly than oils with a more viscous base stock and fewer VII's and pour point depressants. [sarc]

Suggest a quality "uber" 0W oil with a 3.8 HTHS that won't shear and I'll try it. Otherwise I'll go with known performers. A good one is M1, 5W-40 TDT. Redline and Am make some great ones. Of course, while I'm rambling on, the OP is making 200HP and our engines were making 700+ with 20% less displacement.

Castrol 0W40 with HTHS 3.7 won’t shear down fast.
Motul 300V, Redline performance.
Mobil1 0W40 is as far as I know go to oil for many Porsche teams.

 

[tom in boise]

. Of course, while I'm rambling on, the OP is making 200HP and our engines were making 700+ with 20% less displacement.

Hey - 228 hp, I'll have you know....

 

[2EHA]

VII scary

TDT is equally VII ridden and saddled with second rate base stock. one of the best oils in the world vs an american HDEO lol

 

[Craig in Canada]

The coolant will transfer heat faster. If the coolant runs cooler oil will transfer more heat to the coolant. The engine has a fluid/fluid heat transfer box.

I understand that. The coolant won't be cooler if cooling targets are already being met. If cooling targets cannot be met, more diluted coolant will help the system achieve the target.

I am saying that no one has provided evidence that (using the same heat exchanger) heat will travel more quickly from 120C oil to a 100C 25% glycol mixture than it will from 120C oil to a 100C 50% glycol mixture. I do not debate that the 25% mixture can carry more heat (due to higher specific heat capacity).

If the oil/coolant heat exchanger can't keep up while the coolant is maintaining the ECU target temperature, I'm not sure that reducing concentration will do anything, but will be interested to read and find out.

 

[Craig in Canada]

From Volkswagen Self-Study Programme 522 - The 2.0 TSI engine of the 162/169 kW 2012 GTI - Design and function > chapter cooling system, pages 37 and 39:

Great snippet posted there, confirming the ECU has an 85C target while under heavy load. Some actual coolant readings at the completion of a run from the OP would be valuable. If they're way above 85C, then we could conclude that turning on the heater and diluting the coolant would help. (IMO)

 

[edyvw]

I understand that. The coolant won't be cooler if cooling targets are already being met. If cooling targets cannot be met, more diluted coolant will help the system achieve the target.

I am saying that no one has provided evidence that (using the same heat exchanger) heat will travel more quickly from 120C oil to a 100C 25% glycol mixture than it will from 120C oil to a 100C 50% glycol mixture. I do not debate that the 25% mixture can carry more heat (due to higher specific heat capacity).

If the oil/coolant heat exchanger can't keep up while the coolant is maintaining the ECU target temperature, I'm not sure that reducing concentration will do anything, but will be interested to read and find out.

I think 20c decrease just from mixture is too much to expect.

 

[edyvw]

Great snippet posted there, confirming the ECU has an 85C target while under heavy load. Some actual coolant readings at the completion of a run from the OP would be valuable. If they're way above 85C, then we could conclude that turning on the heater and diluting the coolant would help. (IMO)

I don’t think he will meet 85c due to altitude. That is biggest obstacle to cooler temperatures.