Oil weight for track only car with a lot of cooling?

[RT-BRZ]

Originally Posted by GrandSport

Oil doesn't so much "lubricate" rod bearings as it does keep the separate. It lubricates contact surfaces like rings/walls, camshaft lobes, etc.

I know I should just shut up but this is really the whole point about tolerance/clearance.

Everything I've ever seen says that more narrow clearances in things like bearings generally necessitates less viscous fluid to "fit" in between. Generally speaking, modern engines run much tighter clearances in a lot of things to increase things like VE, fuel efficiency, etc. So, generally speaking, "thinner" oil at a certain RPM may not be a problem if the clearances stay within the tolerances that were allowed in the engine design.

So, Tokay is correct. The words were intermixed incorrectly but the relationship is there but not always understood. Words can get complicated when you're not using them on a daily basis like engineers do.

Zdan is also probably correct since the temperature of the oil may not matter as much. I think his hidden point is that oil that runs too cool may actually cause a problem the other way and not allow the oil to "fit" between the bearings, rings, etc. I would also guess that the higher pressure required for thicker oil may actually shorten the life of the oil pump or at least diminish its function.

CSG/Ultramaroon/others are also probably correct that a good oil cooler with thermostat is probably easy insurance without having to move to very heavy weight oil given that most people that want/need this protection are using their cars on the track a lot more than the casual owner. The casual owner may actually be causing themselves unintended harm if they are putting in a cooling solution and not ever getting the engine up to temps that create the need for it.

Topics up next:

Precision vs. Accuracy

Decimation and other words that have become colloquialisms that are no longer true to the original word.

[GrandSport]

Originally Posted by RT-BRZ

I know I should just shut up but this is really the whole point about tolerance/clearance.

Everything I've ever seen says that more narrow clearances in things like bearings generally necessitates less viscous fluid to "fit" in between. Generally speaking, modern engines run much tighter clearances in a lot of things to increase things like VE, fuel efficiency, etc. So, generally speaking, "thinner" oil at a certain RPM may not be a problem if the clearances stay within the tolerances that were allowed in the engine design.

So, Tokay is correct. The words were intermixed incorrectly but the relationship is there but not always understood. Words can get complicated when you're not using them on a daily basis like engineers do.

Zdan is also probably correct since the temperature of the oil may not matter as much. I think his hidden point is that oil that runs too cool may actually cause a problem the other way and not allow the oil to "fit" between the bearings, rings, etc. I would also guess that the higher pressure required for thicker oil may actually shorten the life of the oil pump or at least diminish its function.

CSG/Ultramaroon/others are also probably correct that a good oil cooler with thermostat is probably easy insurance without having to move to very heavy weight oil given that most people that want/need this protection are using their cars on the track a lot more than the casual owner. The casual owner may actually be causing themselves unintended harm if they are putting in a cooling solution and not ever getting the engine up to temps that create the need for it.

Topics up next:

Precision vs. Accuracy

Decimation and other words that have become colloquialisms that are no longer true to the original word.

Disclaimer I dont know this from any reading or source, just my intuition:

I would venture to guess that the advantage of narrower rod bearing clearances is two fold:

First, again, it's not lubrication. You just need oil pressure to "float" the rod from the crank journal. So 0.001 inch or 1 inch, the idea is that they never make contact (that's probably too extreme but you get the point). A tighter clearance will probably mean more uniformity and keeping the two circles more concentric.
They can achieve this because they have developed a greater ability to tighten tolerances.

Second: It lets them run a thinner oil which I would suspect is a big deal for mpg.

There was a whole viper engine fiasco I've read up on to no end. As someone who is always a big advocate of running factory specified fluids (unless there is a good reason, like being track only), I changed my mind. A former Viper engineer said they did a bunch of studies and the thicker oil definitely resulted in less wear, but they were forced to go with the thinner oil for mpg.

Now, I'd imagine some of the guys who play with powertrain regularly can give you a better idea of what the numbers are, but I bet it is significant for them to mandate it despite higher wear. Remember, oil pumping losses are purely rpm dependent, not load dependent. So 2500hp WOT or cruise is all the same to the oil pump. Losing 2 less horses at cruise is a decent amount of mpg.

[Tokay444]

The EPA is what dictates 0W20 in this engine. The Japanese manual references use case and has table with what weights should be used for what use types. It goes to 40. It's the same engine.

[gen3v8]

Originally Posted by Tokay444

The EPA is what dictates 0W20 in this engine. The Japanese manual references use case and has table with what weights should be used for what use types. It goes to 40. It's the same engine.

It definitely is for fuel economy which means less emissions.

[GrandSport]

Originally Posted by Tokay444

The EPA is what dictates 0W20 in this engine. The Japanese manual references use case and has table with what weights should be used for what use types. It goes to 40. It's the same engine.

Wait- the oil spec in Japan is 0W-40? Do they have less cooling or anything?

[Ultramaroon]

Originally Posted by GrandSport

Wait- the oil spec in Japan is 0W-40? Do they have less cooling or anything?

I think it's 10w-40. It really is all about fuel efficiency. It's the same setup globally.

I've forgotten a few times that your thread is about track-only. Oops.

[jflogerzi]

always run 5w-30 even when I was driving my car on the street.

Sent from my Pixel 6 using Tapatalk

[renfield90]

Originally Posted by Tokay444

What do tight tolerances have to do with anything?

https://xkcd.com/386/

Go touch some grass.

[x808drifter]

Originally Posted by renfield90

Go touch some grass.

FTFY

[Tokay444]

Originally Posted by renfield90

https://xkcd.com/386/

Go touch some grass.

Fail.

[Bergycheese348]

FWIW, I have only ran 0W-20 on my car between autocross, track, and DD so far. Verus hood louvers and TRD (HKS) Oil Cooler are the only cooling solutions I have done so far. It has never gone above 'operating temp' on the temp gauge on my dash, even after a 20 minute session giving it it's all.

With adding the supercharger, I am already adding some radiator/oil cooler/heat exchanger ducting, and as we speak I am wiring in my TRD oil temp/pressure and water temp gauges so I can track temps better. With my camera on my rear glass pointing towards the windshield I can view the C/kPa values better in certain scenarios besides watching for them to flash at me.

My logic for keeping it at 0W-20 considering what I have researched and using my school studies consists of flow and tolerances (clearances for those who are picky). Tight tolerances means lower viscosity needed to lubricate the engine correctly. As has been discussed here and is common knowledge, oil dramatically loses viscosity the higher temperature it is. Just for a wild number that is completely not true, 0W-20 might have the same viscosity at 270F as 5W-40 might at 330F (based on where the temperature is being sensed at). Lets just say the oiling is perfectly fine for both of these at this level, but what is not is the engine temps itself. I remember reading that the oil temp numbers recorded can be significantly different than what it would be if you had a sensor on the bearings. It might be 30F or 50F, but that's a big difference and one that could cause failure on the internals themselves. Because of this I want to stay on the side of OEM oil weight, what the engine was designed for, and an effective way to cool that oil rather than throwing in thicker oil and calling it a solution. Besides, thicker oil takes longer to heat up but also retains heat for longer, whereas thinner oil is able to heat up faster (important for me so I can actually drive the car) and also disperses heat a lot easier. Terms may not be used perfectly, but the general point gets across I hope (long and boring day at work, brain does not like to think).

I use this logic for brakes too, in a way. Slapping on extremely aggressive brakes is a coverup for the lack of cooling to the brakes themselves, which aggressive brakes are not good for me since I daily my car. When they are hot after an event and I need to drive home, I do not want to take them out, and they still are hot when I get home, and it keeps getting put in my back pocket. If you can cool your brakes they will last longer and you do not have to run a pad that will destroy your ears when not on a track. Cooling or a BBK is a great solution to this.

All in all, I will keep running with 0W-20 unless I start having a heat issue, and when I do I will find a better cooling solution.

If there is any flaw in my logic please explain it, always looking to learn

[Davidss]

Originally Posted by Bergycheese348

FWIW, I have only ran 0W-20 on my car between autocross, track, and DD so far. Verus hood louvers and TRD (HKS) Oil Cooler are the only cooling solutions I have done so far. It has never gone above 'operating temp' on the temp gauge on my dash, even after a 20 minute session giving it it's all.

With adding the supercharger, I am already adding some radiator/oil cooler/heat exchanger ducting, and as we speak I am wiring in my TRD oil temp/pressure and water temp gauges so I can track temps better. With my camera on my rear glass pointing towards the windshield I can view the C/kPa values better in certain scenarios besides watching for them to flash at me.

My logic for keeping it at 0W-20 considering what I have researched and using my school studies consists of flow and tolerances (clearances for those who are picky). Tight tolerances means lower viscosity needed to lubricate the engine correctly. As has been discussed here and is common knowledge, oil dramatically loses viscosity the higher temperature it is. Just for a wild number that is completely not true, 0W-20 might have the same viscosity at 270F as 5W-40 might at 330F (based on where the temperature is being sensed at). Lets just say the oiling is perfectly fine for both of these at this level, but what is not is the engine temps itself. I remember reading that the oil temp numbers recorded can be significantly different than what it would be if you had a sensor on the bearings. It might be 30F or 50F, but that's a big difference and one that could cause failure on the internals themselves. Because of this I want to stay on the side of OEM oil weight, what the engine was designed for, and an effective way to cool that oil rather than throwing in thicker oil and calling it a solution. Besides, thicker oil takes longer to heat up but also retains heat for longer, whereas thinner oil is able to heat up faster (important for me so I can actually drive the car) and also disperses heat a lot easier. Terms may not be used perfectly, but the general point gets across I hope (long and boring day at work, brain does not like to think).

I use this logic for brakes too, in a way. Slapping on extremely aggressive brakes is a coverup for the lack of cooling to the brakes themselves, which aggressive brakes are not good for me since I daily my car. When they are hot after an event and I need to drive home, I do not want to take them out, and they still are hot when I get home, and it keeps getting put in my back pocket. If you can cool your brakes they will last longer and you do not have to run a pad that will destroy your ears when not on a track. Cooling or a BBK is a great solution to this.

All in all, I will keep running with 0W-20 unless I start having a heat issue, and when I do I will find a better cooling solution.

If there is any flaw in my logic please explain it, always looking to learn

A few things you should consider. The coolant gauge is a dummy gauge, the engine might be a little cold or hot and the gauge is not going to move. Next the oil can be overheated on some engines while the coolant temp is still fine. Next the OEM oil spec is 20 weight in countries where fuel mileage is top priority and 20/30/40 weight (depending on climate) in countries where reliability is top priority. Lastly some of your logic would make more sense is the oil system in these engines was not a known flawed design and an incredibly high amount of cars spin bearings on track.

Ultimately I don't think I am going to convince you probably best for you to wire up your oil pressure and temp gauge and see the numbers for yourself. My oil pressure is still lower than I would like at redline on track with 50 weight and an enormous custom oil cooler. But it is an effective bandaid to cover up the flaws in the oil system design.

[GrandSport]

Well a few things re: above two posts:

1. Thicker oil is NOT a band aid for oil starvation, which is probably why the cars spin bearings at the track.

2. While the ultimate goal is the correct viscosity at all temps, and most importantly, the hot temps a track car sees almost exclusively, different oils lose viscosity at different rates.
Racing oil should lose far less viscosity at temp than a regular synesthetic than dino oil.
But you need to look at your temp. My temps don't go above 210 in the winter and 235 in the 105 degree summer running hard AF on the track for 30 min sessions. That's pretty damn close to OEM temps. My Miatas dont have an oil cooler. It might run hotter oil in the winter because I'm making way more power lol. But my coolant in the summer is like 200 with the biggest radiator you can shoe horn in there, running water + additive and sealing everything off with aluminum tape (very important and overlooked). So very different needs. (I'm strongly considering adding an engine oil cooler + better hubs and just letting them DQ me if I ever podium).

You also need to figure out what optimal viscosity is. If spec in other countries is thicker oil, that's a concern. Do they have the same coolers (or more, or less)?

Running thinner oil to get more efficiency is hardly novel or undocumented. Racers do it to "cheat" and OEMs have known to do it to get better MPG. It's exceptionally well documented in the Viper world, coming straight from the engine engineer's mouth to our monitors. They did testing, found thicker oil reduced wear substantially and were told to use thinner oil by bean counters for CAFE.

Random question: MPG aside, why would tighter clearances be better though? Wouldn't you rather have bigger clearances with higher oil pressure? Obviously there is a limit, but you'd think you'd want more of an oil cloud to ride the crank and rods on.

3. Running street pads on the track is playing with fire and putting everyone else at risk too. Brake ducts definitely help, but you're never going to get enough air in there to run a street pad on the track. What a stupid way to wreck your car, wreck other people's car, hurt yourself and hurt others. I just didn't feel like swapping my brake pads.
It's not like it's significantly more expensive. You're still going to be using up brake pads on the track- street or track pads. The only real meaningful difference is the 45 min it takes to swap them.

[RT-BRZ]

Originally Posted by GrandSport

Random question: MPG aside, why would tighter clearances be better though? Wouldn't you rather have bigger clearances with higher oil pressure? Obviously there is a limit, but you'd think you'd want more of an oil cloud to ride the crank and rods on.

It has always been my understanding that tighter clearances were the result of higher precision machining and manufacturing. It seems logical to me that the tighter clearances allowed for less drag by having the ability to use lower viscosity lubrication. When clearances were bigger, higher viscosity lubrication was needed to "fill the space" to reduce wear. All in the name of efficiency.

At least that's how I've understood it.