Another 2nd-gen engine failure at track...
 

MCA Suspension: It looks like we achieved too much corner grip last Thursday at Queensland Raceway. Whilst testing our MCA Circuit Spec Reds with Advan A050 soft compound tyres, we were rewarded with a nice hole in the block and lots of smoke and fire out the exhaust early on in the day.

https://mcasuspension.com/gr86-engine-failure/

Hmmm, and I'm running Thompson (CT) tomorrow and Saturday, CW track with a 180* oval right-hander...

https://mcasuspension.com/wp-content...22309763_n.jpg

wait 10-40w oil on a fully-stock engine?!?!

ok, how many people are popping motors while running the oem-spec 0-20w? because this makes 2 for sure that are running heavier than oem-spec oil and then have an engine failure.

Failure is not due to running 10w40... At track operating temps, 10w40 is thinner/lower viscosity than 0w20 on the street. Not hurting a thing... I wouldn't want it in my oil pan starting up in near-freezing temperatures though...

shouldn't it be 40weight at temp? where 0-20 is 20weight at temp? how is 40w thinner?

anyway, my main point is that they're deviating from manufacturer specified thicknesses like none of it matters, and then get a shocked face when the motor blows up...

simply show me that more blown motors have ran 0-20 for oil than trackbro's running something different, and i'll rest my case.

10w50 at 275F is about as thin as 0w20 at 210F according to this plot:
https://www.subaruoutback.org/cdn-cg...bb-png.489375/

There is no way under track usage that the 10w40 oil they were using was "too *thick*". Unless 0w20 is too thick at 210F...

If you know *anything at all* about how engines work and how oil viscosity vs. temperature works, you'll know that this engine did not fail because 10w40 is "too thick" for the engine.

Loose RTV worms in the engine have been shown and in fact they found them in the pickup tube for my '23. And oil pressure drop during extended right-handers at the track has also been shown. IMO these factors are a *lot* more critical than whether running 0w20 or 10w40 (or whatever).

We do not have access to enough data, but IMO if there is no RTV blocking oil passages, and if there is no pressure loss during hard cornering on seriously grippy tires, the engine is likely going to live a decent life whether running 0w20 or 10w40 at the track. But if there are random RTV blobs in critical passages, combined with *consistent* loss off oil pressure during right-hand turns, engine may be short-lived whether running 0w20 or 10w40.

These engines are not expiring due to peeps running 5w30 or 10w40 or 20w60 or whatever.

10W-40 makes sense tracking in Australia I think.


Most people tracking in North America seem to use 5W-30. The manual recommends 0W-20 with cold conditions in mind, and even then, it's probably mostly for fuel economy. Manuals in other markets (Australia, Japan) say that heavier oil is fine.



The problem with the FA24 is more fundamental than, "use the 'wrong' oil and it will explode."

There's a 7 page discussion on this already over on that other 2nd gen forum we can't link to directly. Car was also tuned and running on E85 so it adds other variables in what possibly caused the failure.

From the NASIOC Forums
https://forums.nasioc.com/forums/sho....php?t=2714154


Small excerpt below:



"If Subaru recommends 0w20 for your engine, the bearings should be very happy with 7.5 cSt oil, if we put RC 5w30 into the engine, the oil temperature can rise to 240°F before the oil viscosity drops below 7.5 cSt, now we're at the upper limit of optimal oil temperature. With HD 5w30 the 7.5 cSt temperature rises to 260°F, basically the upper limit of acceptable. In other words, using a 40 grade oil implies we will be operating the engine at unacceptably high oil temperatures. And since using a heavier oil encourages higher operating temperatures, we're compounding the problem. So, if you think you need 5w40 in your car that calls for 0w20, what you really need is an oil cooler, possibly a big one.

The same logic goes for a car that calls for 5w30, the bearings should be very happy with oil at 10 cSt, stepping all the way up to 50 grade implies oil temperatures in excess of 260 °F, well outside the optimal range. So why did Subaru formerly recommend up to 50 grade oils for heavy use and high temperatures? Simple, it's a band-aid for the small fraction of owners who use their cars that heavily. Subaru's choice was either add an oil cooler to every car they made, which costs them money, or put the heavy oil recommendations in the manual, which costs them nothing.

The above chart is viscosity for new oil, but what about used oil? The lines in the chart simply move down as the oil shears, but they retain their shape. Since we don't know Subaru's exact design point any way, the conclusions about oil choice hold whether we're looking at a graph of used oil or new.

We've talked a lot about viscosity here, but what about other requirements? The API/ILSAC specs called for by Subaru ensure acceptable performance in areas like compatibility with seals, detergency, and TBN. Note that many oils, especially top-tier synthetics, exceed the minimum requirements by a substantial margin, and can therefore be expected to handle substantially longer change intervals or more severe service than the minimum-spec oils Subaru must assume when making recommendations."

Uh oh. ZDan hates oil coolers.

This "logic" is total, 100% b.s. The argument seems to be that since 5w30 doesn't drop below 7.5 cSt until it gets much hotter, then that means it *has* to run hotter to be "optimal"? In the *real* world, my car ran ~275 oil temps with 0w20 and ~275 oil temps with 5w30. The difference is that with 5w30 the kinematic viscosity is a lot closer to 7.5 and the 0w20 kinematic viscosity has fallen below 5.

Also, 275F *indicated* in the BRZ is more like 255F sump oil temp. And any decent synthetic is good for 300F+

I don't *hate* oil coolers, I just don't think they are a requirement for most of our cars.

Another 2nd-gen engine failure at track...
 

Brother, this isn’t just some logic, it is the compilation extensive research and backed up by easily accessible info from the sources provided, companies, labs etc. So take it with a grain of salt. Do what you wish the info provided.

It is also well known that the oil temps on the dash are highly inaccurate and shall, not should, shall be monitored by a proper temp gauge.

I didn’t post it to argue, is more informational than anything. Again, do what you wish with the info provided, peruse the complete post, feel free to share your thoughts on the NASIOC forum.

Also, I saw that you’re coming to CT to race at Thompson which is a track that Ive been dying to go to. I do wholeheartedly wish you the best of the time. I wish I gathered the enough confidence and courage to track my BRZ. I’ve secluded my self to race simulators.

You provided NO information. Dude *supposes* that since 5w30 has to be hotter to drop below 7.5 cSt, that somehow that's encouraging higher temps? I mean it's *laughable*. No actual temps shown at all.

Yeah but it's *something* at least. Your source is just spouting nonsense with NO quoted temps, just the patently *absurd* idea that since 5w30 has to run much hotter to drop below 7.5 cSt that somehow it's encouraging higher temps? Ridiculous.

IMO your quoted text from the forum is useless. Forum might be OK, I've no idea, but what you have brought over from them is worth nothing. IMO!