10W-50 oil in BRZ?

[ZDan]

Akshually...
At 270F operating temps, HTHS at 150C is probably more relevant than rated viscosity, as HTHS is at 150C/302F while rated viscosity is at 100C/212F. Here's another chart I grabbed from quick interwebz search, which I have no proof of, to be taken with grain of salt of course:

source: https://www.q8oils.com/automotive/low-hths-oils/

I've seen 3.5 HTHS as a general minimum recommendation for track usage at high oil temps. Some say 3.0 is fine, which chart above appears to corroborate. Most 0w20 synthetics are 2.5 - 2.9. *IF* I were to run 0w20 at the track, I'd try to get one with HTHS at the higher end of that range...
30-weights start at 3.0 HTHS, Redline 5w30 I've been running is 3.7.

[ZDan]

Originally Posted by KillerBMotorsport

Where are you measuring your oil temps? OEM sender?

Yup. I fully understand that this is a reference value and not necessarily an absolute maximum...

[KillerBMotorsport]

Originally Posted by ZDan

Yup. I fully understand that this is a reference value and not necessarily an absolute maximum...

Bingo. Not only that, but the OEM location can have up to a 20° temp discrepancy vs the sump.

[TommyW]

You can buy a fully set up car for Toyota’s new racing series for the GR 86 and it comes with an oil cooler but not sure of the recommended oil viscosity

[x808drifter]

Originally Posted by ZDan

100% BS? "Actual proof"?

FTR I don't think I've said "you NEED to run XwXX!". I've said that if you operate for extended periods at 270F+ as I do, it's probably good idea to run something thicker than 20-weight. I don't think this is a radical idea...

The viscosity of a 20-weight oil at 270F is going to be a LOT less than it is at normal operating temps of 190-220F. Running 30- or 40-weight at 270F is going to get you closer to what the viscosity of the factory-fill 0w20 is at normal street oil temps. Personally, I've been running 5w30 during track season, may go to 0w40 or 5w40 this year.

Feel free to run 0w20 at 270F while waiting for "actual proof" though!

That wasn't meant at you directly. More for those in here that have said you need to run a certain weight. (although it does look that way)

And again nobody is arguing that oil gets thin at hot temps.
I just asked for proof for some of your comments like

Running 30- or 40-weight at 270F is going to get you closer to what the viscosity of the factory-fill 0w20 is at normal street oil temps.

Where did you get this info from?
That is all I am asking. My Google-Fu is failing me when it comes to finding actual tests for this stuff. (Being at work isn't helping)

Or are you just regurgitating stuff you heard over the years?
Just like the ol' 10PSI of oil pressure per 1k RPM.
That was a rule of thumb for small block Chevy's and nothing else. Yet people still spread that one around like it applies to all motors.

[Tokay444]

Originally Posted by TommyW

You can buy a fully set up car for Toyota’s new racing series for the GR 86 and it comes with an oil cooler but not sure of the recommended oil viscosity

5W30

[TommyW]

Originally Posted by Tokay444

5W30

far from 50

So for racing conditions the factory recommends an oil cooler and 5-30. That should be a reliable setup.

[Tokay444]

Originally Posted by TommyW

far from 50

So for racing conditions the factory recommends an oil cooler and 5-30. That should be a reliable setup.

Have any actually raced yet? Have they made in through an entire season on one engine? Have they made it through an entire race?

[ZDan]

Originally Posted by x808drifter

That wasn't meant at you directly. More for those in here that have said you need to run a certain weight. (although it does look that way)

I recommend running 30 (or 40) weight, for sure. But I have run at a couple of track events with 0w20 myself...

And again nobody is arguing that oil gets thin at hot temps.
I just asked for proof for some of your comments like
"Running 30- or 40-weight at 270F is going to get you closer to what the viscosity of the factory-fill 0w20 is at normal street oil temps."
Where did you get this info from?
That is all I am asking. My Google-Fu is failing me when it comes to finding actual tests for this stuff.

I don't get your confusion here. It would seem pretty obvious that a 30-weight oil, which is required to be quite a bit thicker than 20-weight at the reference temp of 100C/212F, is likely to still be thicker at 270F as well. In general. You *might* be able to find some 0w20 oil at the thicker end that is as thick at 270F as the lightest-actual-weight 30-weight synth. But if you compared same make/model of oil in 0w20 vs. 5w30 synth, I don't think you'd ever find the 20-weight to be as thick at 270F as the 30-weight...

If you want *proof* of higher effective viscosity of 30- or 40-weight vs. 20-weight at higher temperatures, go by HTHS (high temperature high shear) which is at 150C/302F. As I posted above ^^^ this is really a better metric for our purposes.

[KillerBMotorsport]

Originally Posted by ZDan

I don't think you'd ever find the 20-weight to be as thick at 270F as the 30-weight...

Part of the problem here that hasn't even been touched is different oil brands. None use the same additive packs. You compare M1, Amsoil, Rotella, Motul, Driven, etc... and results will vary even with sticking to the same listed viscosities.

Like most 'what oil should I run' threads, it becomes a hair-splitting train wreck at some point, and there just is no one answer fits all. I will say it every time, get an analysis done if you REALLY want to know what oil is going to provide optimized results for YOU; your driving style, level of mods, environment, track/event type, engine wear, fuel, etc...

[gen3v8]

Originally Posted by KillerBMotorsport

Bingo. Not only that, but the OEM location can have up to a 20° temp discrepancy vs the sump.

So is the sump oil temp hotter/cooler than the oem reading?

[KillerBMotorsport]

Originally Posted by gen3v8

So is the sump oil temp hotter/cooler than the oem reading?

Depends on how far off the scale is on the OEM sender. An aftermarket unit will not only be more accurate but will read changes more rapidly as well (less delay). Every car we've measured both on, the OEM location read higher, by as much as 20 degrees. Worse when on the colder side of the scale.

[ZDan]

Originally Posted by KillerBMotorsport

Part of the problem here that hasn't even been touched is different oil brands. None use the same additive packs. You compare M1, Amsoil, Rotella, Motul, Driven, etc... and results will vary even with sticking to the same listed viscosities.

Another reason it's a better idea to go by HTHS if concerned about viscosity at higher temps. Different oils with the same viscosity rating can and do have different HTHS:

Mobil1 0w20, 5w30, 5w40
HTHS: 2.7, 3.0, 3.9

Redline 0w20, 5w30, 5w40
HTHS: 2.9, 3.7, 4.4

Motul 300V 0w20, 5w30, 5w40
HTHS: 2.7, 3.5, 4.1

HTHS is at 150C/302F, so between the rated viscosity at 100C/212F (i.e. 20-weight, 30-weight etc) and the HTHS value you should have a decent idea of the relative viscosities of different oils at the temps our engine oil sees during track usage.

[gen3v8]

^^^ So an oil with HTHS of 3.04 will be perfect for track use with an oil cooler keeping OEM reading @106C max?