0W20 vs. 5W30 Test Data

[Twinz]

I have pretty much just glanced at these oil threads because Autocrossing is the hardest work my car has to deal with and I change my oil frequently. (every 3-4 events)

However, I think I should consider different oil for the Tail of the Dragon visit I make once a year. The 350Z I ran for the last decade had a cooler "collar" sandwiched between the oil filter and the block with coolant running through it,(stock). Good brake pads, and high-temp brake fluid was all I did to "prep" for that road. The speeds aren't that high up there, but if/when I get an open run with no traffic , I could end up in the top-half of the tach for over 10 minutes.

This is still brief compared to an HPDE, but a lot more than the car has to deal with when autocrossing. Should I bother with thicker oil for the trip?

[GSpeed]

Originally Posted by Twinz

I have pretty much just glanced at these oil threads because Autocrossing is the hardest work my car has to deal with and I change my oil frequently. (every 3-4 events)

However, I think I should consider different oil for the Tail of the Dragon visit I make once a year. The 350Z I ran for the last decade had a cooler "collar" sandwiched between the oil filter and the block with coolant running through it,(stock). Good brake pads, and high-temp brake fluid was all I did to "prep" for that road. The speeds aren't that high up there, but if/when I get an open run with no traffic , I could end up in the top-half of the tach for over 10 minutes.

This is still brief compared to an HPDE, but a lot more than the car has to deal with when autocrossing. Should I bother with thicker oil for the trip?

It wouldn't hurt anything, and if it gives you more piece of mind, then it's probably worth it. That being said, I doubt you'd be risking damage by sticking with 0W20.

[NLSP]

For what it's worth, the owner's manual says "0W-20 is the best choice for good fuel economy and good starting in cold weather", and actually suggests running a higher viscosity oil "if the vehicle is operated at high speeds, or under extreme load conditions".

[Calvin27]

Last one before I pull the trigger. Is the radiator ok? I notice a lot of the oil coolers obstruct a pretty big part of the radiator. My car philosophy is about reliability - more time on the track than the pits.

[Icecreamtruk]

Originally Posted by Calvin27

Last one before I pull the trigger. Is the radiator ok? I notice a lot of the oil coolers obstruct a pretty big part of the radiator. My car philosophy is about reliability - more time on the track than the pits.

I did get a larger radiator at the same time I got the oil cooler for this same reason. Not only is part of it kind of blocked, hotter air is passing by (heat from the oil cooler).

I tracked the car before getting an oil cooler or radiator (I know, I didnt know better back then) and when I would come out the engine bay will smell like burning metal. Similar to overheated brakes smell, but it was coming from the engine. This was after 20 minutes of track.

After getting oil cooler and radiator, the car doesnt smell anything at all and it doesnt even feel hot when I open up the hood (I would get a wave of super heated air to the face when opening it previously). And I have done 20 minutes to 1 hour sessions, the engine is/feels the same after both times.

Still using 0W20.

[Jonsey]

The stock radiator is fine if you are N/A. I track in the Texas summer heat without issue. I am sure the GSpeed team can pull some of their data to back this up.

[redlined600]

I have logs as well that show no issues with the stock radiator with an oil cooler in front. Some of which were on a "power" track with lots of wot. Granted ambient temps were only in the midish 70s*f.

[dutchman1]

My 86 will see about 20k street miles and 150-200ish autocross runs a year in the Seattle area. Winter weather usually doesn't go much below freezing, and summer heat rarely tops 85. Would it be beneficial to switch to 5w30 with that amount of autox use? If so, what are the disadvantages of running 5w30? Does the higher viscosity cause a lower power output? Does the car need warm up longer when temps occasionally dip in the teens/twenties?

[DarkSunrise]

Originally Posted by redlined600

I have logs as well that show no issues with the stock radiator with an oil cooler in front. Some of which were on a "power" track with lots of wot. Granted ambient temps were only in the midish 70s*f.

Agreed. Even in 95 F weather, I haven't seen any issues in my logs with the stock radiator and a Perrin OC in front. Water temps peaked at 207 F, oil temps at 243 F using 5w30.

[swarb]

Originally Posted by dutchman1

My 86 will see about 20k street miles and 150-200ish autocross runs a year in the Seattle area. Winter weather usually doesn't go much below freezing, and summer heat rarely tops 85. Would it be beneficial to switch to 5w30 with that amount of autox use? If so, what are the disadvantages of running 5w30? Does the higher viscosity cause a lower power output? Does the car need warm up longer when temps occasionally dip in the teens/twenties?

You are fine with 0w20. Autocross runs are too short for the oil to get hot enough to need something else.

[GSpeed]

Originally Posted by Jonsey

The stock radiator is fine if you are N/A. I track in the Texas summer heat without issue. I am sure the GSpeed team can pull some of their data to back this up.

Agreed, engine coolant temps are not a problem.

[cueball89]

Originally Posted by swarb

You are fine with 0w20. Autocross runs are too short for the oil to get hot enough to need something else.

I've seen 230f-240f in autocross. Corresponding oil pressure at idle was 3-5psi. My next oil change will be with a thicker oil.

[bem75]

A little late to the party, but we're having a similar oil debate. My situation is a bit different, as my car is 100% dedicated race car. FI with Jackson Supercharger. We run 40 minute races. We ran Motul 0W-40 and Pennzoil Ultra Platinum 0W-40, last year.

I've had recommendations to run Torco SR-5r 5W-30. But I've also had a fully built race engine and the builder recommended Redline 15W-50. The general consensus seems to be 5W-30 for stock internals and factory clearances.

We do see high water and oil temps and we maintain those high temps for a 40 minute race. We're seeing around 260F oil temp.

I've compared viscosity numbers (published) for several oils. My concern is the 100C viscosity of most 5W-30 oils is around 11 or 12. When that temp hits 127 C, the viscosity will be quite a bit lower.

So, where is the sweet spot for a race engine? We ran the 15W-50 and temps climbed rapidly. I've also been advised by others in the know that they would never run a 50wt oil in the FA20. For stock clearances, I would agree with that. For a built engine, I tend to go with what the builder recommends.

Looking at the Pennzoil Ultra Platinum 0W-40, it has a viscosity at 100C of 13.7. Torco 5W-30 @ 100C is 11.96.

As a note, a fellow racer with the exact same setup as mine ran a full season with Torco 5W-30 and had no issues. So, for a stock engine with FI, I'm interested to know the differences, under racing conditions, between 5W-30 and 0W-40. Any thoughts?

[cueball89]

This calculator can extrapolate oil viscosity at a different temperature.
http://www.viscopedia.com/calculator...extrapolation/

The viscosity at 127 C with Pennzoil is roughly 8.3 and would be 7.2 at the same temperature with the Torco.