Forester XT (2.0 DIT) - 5w-30 required, why not 0w-40 for track use under boost then?

[CSG Mike]

Originally Posted by glamcem

Back to topic, are you suggesting a higher weight oil (made by same high quality manufacturer say for instance Motul 0w-20 vs 5w-30) doesn't equate more protection at certain temps especially under boost + hard driving?
Again, I am not questioning the quality of the motor oils solely based on their viscosity but I just want to learn the logic behind using the bare minimum that is suggested/designed for a stock (or close to stock) car when adding 60-70% more hp with FI and more importantly when pushing it to the limits (HPDE-AutoX ..etc)..

Yes.

Just because you're running boost, doesn't mean your engine tolerances are changed. The tolerances are what determine your oil weight, not your power output. If you're using thicker oil to compensate for running hotter, you're putting a band-aid on an overheating problem. The real solution is to get better cooling to bring the temps down to an acceptable range.

[D K]

What are the actual differences in tolerances between the FA20 and the FA20DIT?

I bought 5W30 Torco for the Chukwalla event but when I got home, I discovered it was 10W30....
My bad for not checking...

I could feel the engine a littl bit down on power, but that may or may not have been a contributing factor.

Curious about the tolerances though..

[Zach3794]

I don't know if you guys understand what Mike means by tolerances. The tolerances he's referring to are the distances between crank bearings and crank, rod bearings and connecting rod surfaces, etc. The amount of distance the oil has to fill to create a barrier which prevents contact of two metal surfaces. Tolerances do not change when throwing boost into the equation, they're the same internals you had before you slapped a turbo or whatever on there. 0w-20 is recommended because it fills the gap between metal surfaces on moving parts the most accurately on our FA20 engine. On the FA20DIT, the bearings, rods, and pistons are all different. Maybe more. The gap between moving metal parts in that block (tolerances) are larger, and therefore require a thicker weight oil (5w-30).

As far as going between 5w-30 and 10w-30, the only difference will be in startup before the oil is heated up. At operating temperature, both of those oils are rated as a 30 weight. That said, different brands of 5w-30 can have variances in the specific viscosity. As an example, perhaps Mobil 1's 0w-20 is more of a 23 weight at temp and Redline's 0w-20 is more of a 19 weight at temp. Who knows, you could calculate it if you really want to given the specs on the bottle.

What's most important in the end game is exactly what Mike said before: unless you're physically tearing into the engine and changing the internals and the new tolerances are different than the factory tolerances, use the factory recommended oil weight. If you're having oil overheating issues, buy an oil cooler.

[D K]

^^^
Hence why I asked:
What are the differences in tolerances between the 2 engines.

[Zach3794]

Originally Posted by D K

^^^
Hence why I asked:
What are the differences in tolerances between the 2 engines.

As I don't have a spare FA20DIT block to break out and a handy caliper to measure with, I couldn't say. Only that the bearing tolerances in the FA20DIT are quite clearly larger to necessitate the thicker oil weight.

[glamcem]

Originally Posted by D K

^^^
Hence why I asked:
What are the differences in tolerances between the 2 engines.

I also would love to see this since I highly doubt the these two engines are very different..Hence the word "FA Series"

[glamcem]

Originally Posted by Zach3794

As I don't have a spare FA20DIT block to break out and a handy caliper to measure with, I couldn't say. Only that the bearing tolerances in the FA20DIT are quite clearly larger to necessitate the thicker oil weight.

Was your previous post based on an assumption then?

On the FA20DIT, the bearings, rods, and pistons are all different. Maybe more. The gap between moving metal parts in that block (tolerances) are larger, and therefore require a thicker weight oil (5w-30)

[glamcem]

Originally Posted by CSG Mike

Yes.

Just because you're running boost, doesn't mean your engine tolerances are changed. The tolerances are what determine your oil weight, not your power output. If you're using thicker oil to compensate for running hotter, you're putting a band-aid on an overheating problem. The real solution is to get better cooling to bring the temps down to an acceptable range.

I never mentioned that I am looking for a band aid solution, I am just saying higher viscosity oil should be more protective when using same cooling method (assuming you have the best oil cooler ever made).

Below figures are taken from Motul's website

300V Power Racing
5W-30
PROPERTIES

Viscosity grade SAE J 300 SAE 5W-30
Density at 20°C (68°F) ASTM D1298 0.859
Viscosity at 40°C (104°F) ASTM D445 64.0 mm²/s
Viscosity at 100°C (212°F) ASTM D445 11.0 mm²/s
HTHS viscosity at 150°C (302°F) ASTM D4741 3.5 mPa.s
Viscosity index ASTM D2270 165
Pour point ASTM D97 -48°C / -54.4°F
Flash point ASTM D92 232°C / 449.6°F
TBN ASTM D2896 7.97 mg KOH/g

300V High Rpm
0W-20

PROPERTIES

Viscosity grade SAE J 300 SAE 0W-20
Density at 20°C (68°F) ASTM D1298 0.853
Viscosity at 40°C (104°F) ASTM D445 42 mm²/s
Viscosity at 100°C (212°F) ASTM D445 8.0 mm²/s
Viscosity index ASTM D2270 166
HTHS viscosity at 150°C (302°F) ASTM D4741 2.7 mPa.s
Pour point ASTM D97 -51°C / -59.8°F
Flash point ASTM D92 222°C / 431.6°F
TBN ASTM D2896 7.97 mg KOH/g

I would love to see the engine tolerances of both engines so that we can compare . Since service schedule for FT86 also mentions that a 5w-30 can be used, I am not sure why we are being so skeptical about using a higher viscosity oil in our cars. I think we all agree that 0w-40 is not twice as thick as 0w-20 right? It just provides better viscosity at/or above 100°C (212°F)

And, bigger power output generates more heat regardless of the engine size or the application (NA, FI..etc) ... 350hp engine will always generates more heat than a 200hp engine which ultimately asks for a better lubricating and cooling..

[CSG Mike]

Originally Posted by glamcem

I never mentioned that I am looking for a band aid solution, I am just saying higher viscosity oil should be more protective when using same cooling method (assuming you have the best oil cooler ever made).

Below figures are taken from Motul's website

300V Power Racing
5W-30
PROPERTIES

Viscosity grade SAE J 300 SAE 5W-30
Density at 20°C (68°F) ASTM D1298 0.859
Viscosity at 40°C (104°F) ASTM D445 64.0 mm²/s
Viscosity at 100°C (212°F) ASTM D445 11.0 mm²/s
HTHS viscosity at 150°C (302°F) ASTM D4741 3.5 mPa.s
Viscosity index ASTM D2270 165
Pour point ASTM D97 -48°C / -54.4°F
Flash point ASTM D92 232°C / 449.6°F
TBN ASTM D2896 7.97 mg KOH/g

300V High Rpm
0W-20

PROPERTIES

Viscosity grade SAE J 300 SAE 0W-20
Density at 20°C (68°F) ASTM D1298 0.853
Viscosity at 40°C (104°F) ASTM D445 42 mm²/s
Viscosity at 100°C (212°F) ASTM D445 8.0 mm²/s
Viscosity index ASTM D2270 166
HTHS viscosity at 150°C (302°F) ASTM D4741 2.7 mPa.s
Pour point ASTM D97 -51°C / -59.8°F
Flash point ASTM D92 222°C / 431.6°F
TBN ASTM D2896 7.97 mg KOH/g

I would love to see the engine tolerances of both engines so that we can compare . Since service schedule for FT86 also mentions that a 5w-30 can be used, I am not sure why we are being so skeptical about using a higher viscosity oil in our cars. I think we all agree that 0w-40 is not twice as thick as 0w-20 right? It just provides better viscosity at/or above 100°C (212°F)

And, bigger power output generates more heat regardless of the engine size or the application (NA, FI..etc) ... 350hp engine will always generates more heat than a 200hp engine which ultimately asks for a better lubricating and cooling..

Wrong.

Perhaps you should do some oil temperature logging, and then revisit your own post. More power =/= higher oil temps.

[CSG David]

Higher viscosity =/= better cooling...

Gawd. Working as an aircraft propulsion systems engineer...this hurts my brain...

[glamcem]

Originally Posted by CSG Mike

Wrong.

Perhaps you should do some oil temperature logging, and then revisit your own post. More power =/= higher oil temps.

I certainly will and report back

My question is, if more hp doesn't cause higher oil temps, why bother upgrading to better oil coolers, intercoolers, oil etc?

[glamcem]

Originally Posted by CSG David

Higher viscosity =/= better cooling...

Gawd. Working as an aircraft propulsion systems engineer...this hurts my brain...

who said that?

[CSG Mike]

Originally Posted by glamcem

I certainly will and report back

My question is, if more hp doesn't cause higher oil temps, why bother upgrading to better oil coolers, intercoolers, oil etc?

Because high RPM causes higher oil temps. Better grade oil provides better lubrication, shear resistance, detergent packages, and life. Intercooler has virtually no relation to the oil temp. Neither does a radiator, unless you're using an oil-water cooler.

[CSG David]

Originally Posted by glamcem

who said that?

I think after reading up all your posts, I have gotten lost in your assessment and thought you were looking for better cooling characteristics using higher viscosity oil. Self-pwnd reading comprehension.

I should sleep. There are parts of this thread that hurts my brain and I'm not sure if this is serious or not. Definitely good luck with your testing.