Running different oil weights for summer season (AutoX/Track)
 

Looks like it’s pretty well understood 0W-20 (the recommended oil) gets thin at high temps based on its viscosity.

Spoke with a gen 1 owner who mentioned only in the summer when doing track and autocross days he switches to 5w30 in stead of 0w20. Anyone doing the same by chance? His cars at 100k+ of beating the hell out of it.


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Plenty of people update to 5w-30 or 0w-40 and sometimes more in hot weather seasons or especially track and autocross. There's also plenty of people that just sit at 0W-20 forever (mostly folks who don't see the track). It really depends on your use of the car. But 5W-30 isn't a huge step up from 0W-20 and is perfectly acceptable. It is even mentioned in the manual if you are so particular about that stuff.

My main use has currently been daily driving my BRZ, so I haven't bothered switching to a higher weight oil. I tried it one summer, noticed basically no difference in oil temps, and decided to go back to 0W-20 and have stuck there since.

Higher viscosity oil won't do anything to the oil temp, but it should keep the oil pressure higher in higher temps. Sadly there is no OEM oil pressure sensor (only a switch) so without adding an external sensor and gauge you can't really verify the benefit of higher viscosity oil.

My bad, you're correct, not sure why I had that confusion. In any case, the pressure difference at these two oil weights is so minimal in a DD that I just went back to stock spec'd oil weight.

I’ve always ran 0w20 + an oil cooler

I've owned my GR for a year now. It gets super hot here in the summer plus Autox. I'm thinking of switching out of the OEM weight. The Manual does say 5w-20 can be used.

Also, based on this video. This Engine loves to be hot. I noticed this last summer while driving under heavy loads. I felt the car get quicker. It happened again last weekend. Or I'm going completely insane and my brain thinks it's happening.

https://www.youtube.com/watch?v=uapDj34-wIs&t=606s

If you're tracking the car, IMO good high-HTHS (high-temp/high-shear) 5w30 is a must. I ran Redline 5w30 in the '17 and will run that in the new '23 for track season as well. They advertise HTHS of 3.7 mPa-s, where 5w30 is 3.0 minimum, and 0w20 can be as low as 2.6 (I think these #s are correct but going off top of head here...)

You don't have to "verify" anything with oil pressure readings, 0w20 have a known specified viscosity and HTHS range, any 5w30 will definitely have greater viscosity and greater film strength at higher operational temps.

Avg highs of 82/84 in July and August is "super hot?"

Don't ever move south of the Mason-Dixon line, you'll melt.

5W-20 is the way to go. A few folks on another GR forum I can't write on here otherwise it wont let me post had a thread, and one of the folks who was chiming in is a pretty credible source of information as he works in that industry.

The TLDR is that with 5w-20, engine happy and better protected at full temp and during spirited driving without sacrificing anything but a few MPG's during your first 15 mins or so while it's warming up and that running super thick oils just for the hell of it isn't a great idea.

Yeah, I autoX once a month during summer months. Not sure if I should switch over or keep my OEM weights? I'll figure it out... I don't drive the car much, only on weekends to get bagels or breakfast for the wife and kids- which I look forward to all week.

If it's just one a month, 0w-20 is fine. Just about everyone here running gen 2's runs 0w-20, including top-dog national level drivers. They push their cars hard.

I've run 0w-20 in my 2017 the last 3 seasons. This past Saturday, we did 12 (yes, 12) back to back runs at the Starting Line School on a ~35 second course. My oil temp gauge stayed around 235 and I'm surprised it didn't go much above that considering 12 runs with about ~1 minute in between each is a lot. At normal events, it rarely gets above about 220 by the end of a run and cools down to ~200 before the next.

I do recommend a "better" oil if you are autocrossing though. I run Motul, but Redline, etc... IE, an oil you're probably going to pay a bit more for, but might resist wear over the longer term better than OEM.

Track days are when you need to start looking at 5w-30's. From what I can tell through my testing, you won't get the oil hot enough during even repeated autocross runs to warrant any pressure benefits from the 5w-30.

5W20 isnt that far off your OEM weight, and it's already in the manual in gray area fine print that you can run that weight anyways lol. That being said, I'd be changing your oil after every event if you're doing some hard hard driving.

just be warned, 5w-30 is not listed as an allowable engine oil formulation in the owners manual, so if you're concerned about maintaining the factory warranty, don't run anything outside of 0w-20.

My FA20 spun a bearing on 5w-30 during an autox, 117k miles, the last 40k miles were on 5w-20, first 75k we’re on 0w-20, sticking with 0W-20 for the second build. ymmv

Thats odd... I thought 5w-30 give better protection because it retain better oil presure

Run 0w40 Mobil1 FS year round and forget about worrying about oil.

Without a shadow of a doubt, I can say the reason the bearing spun had nothing to do with the oil's viscosity numbers.

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https://media1.giphy.com/media/XKFAd...giphy.gif&ct=g

I'd say part of that is actual national level drivers aren't worried about their warranty and don't care about dropping the pan to check for excess RTV.

Those guys operate at a different $$$$ level than us middle-class plebs for the most part.

Depends on which book you look at. It just says "USE 0W-20 Synthetic" Page 42 of the 2023 BRZ Getting Started Guide:

ENGINE OIL
Use 0W-20 synthetic, with one of the following specifications:
• API classification SN with the words “RESOURCE CONSERVING”, SN PLUS with the
words “RESOURCE CONSERVING”, or SP with the words “RESOURCE CONSERVING”.
• ILSAC GF-5 or GF-6A, which can be identified with the ILSAC certification mark
(Starburst mark).


https://techinfo.subaru.com/stis/doc...2306A_STIS.pdf


Page 382 of the 2023 Owners Manual says:

0W-20 synthetic oil is the required oil for optimum engine performance and protection. Conventional oil may be used if synthetic oil is unavailable.*: If 0W-20 synthetic oil is not avail-able, 5W-30 conventional oil maybe used if you need to add oil. However, you should change to 0W-20 synthetic oil at the next oil change

So they are saying use 5W-30 in a pinch, not they are suggesting running it full time.

https://ownersman.com/manuals/2023-S...-owners-manual

but it's really only for warranty coverage.

we could all run 75w gear oil if we so desired, nothing is physically stopping us...

Well it's also the spec they designed for which they designed the engine.

So run some 75w-140w probably have great oil pressure.

0W20, 5W20, and 5W30 are all accepted oil weights (to run full-time, not just in a pinch) in the australian and japanese owner’s manuals. They have the same engines. The TMNA insistence on 0W20 is almost assuredly just for fuel economy reasons.

Just run 0w20 and change it more often, it’s not hard to do. My 16 BRZ is a commuter and I change every 5k, even though Blackstone said to go more. No track for me, if I was, I would just make sure I was not too far into my OCI (2000-3000) and then change it after the event.

I am doing it, 5W30 for summer when I am doing track and autocratic, will switch to 0W20 in winter.

Someone needs to measure oil pressure on the same long sweeping turn on the track with both oil weights. I wonder if the thicker oil will actually lead to better oil pressure. Logic says it should but I wonder.

Already been done on FA20.

https://www.ft86club.com/forums/showthread.php?t=91820

100% agree with that!

Like anything else you may read/watch on the internets, feel free to take anything I'm saying with a grain of salt, do your own research etc... but it seems to me that 0W20 being recommended as a one-size-fits-all solution is entirely down to EPA mandates and automakers striving to hit fuel economy numbers.

Here's an article from 2012, which I believe is a year after the 0W20 mandate came into play:
https://www.consumerreports.org/cro/...cars/index.htm

I'd suggest it has nothing to do with "tighter manufacturing tolerances" and everything to do with legislation.

And remember, the EPA doesn't care how long your engine lasts.

Looks like 5w30 is a good idea for hot weather tracking. I am street only so sticking with 0w20, plus I have two very good oil analysis going with 5k changes.

Thicker oil will lead to higher measured pressures... but oil pressure in and of itself is less significant than oil flow volume and lubrication.

I added a half quart of 5w30 for my freebie Toyota track day at Summit Point to feel a little better, lol. This was on top of 1000 mile old M1 0W20.

Didn't really matter because I hardly got any hard laps in. Barely cracked 240F, obviously no problems. We only got two actual HPDE sessions and there were multiple people driving at public road speeds, unable to even waive people past. So big trains formed etc.