Oil weight for non-daily driven track/autocross cars

Chad Culbertson · **Posted:** Wed Jan 13, 2016 2:37 pm

What do you guys with track/autocross cars that aren't daily driven use for oil? I'm thinking something heavier weight is generally preferred especially for track since the oil would get quite a bit warmer.

FrancisChan · **Posted:** Wed Jan 13, 2016 2:46 pm

Rotella T6 5w40? The turbo miata guys have had good luck with it.

Alec Moody · **Joined:** Fri Feb 15, 2013 9:02 am **Posts:** 299

Yeah, Rotella T6 is my go to oil based on miataturbo people's research. My understanding is that the formula has changed twice since then.

Chad Culbertson · **Posted:** Wed Jan 13, 2016 3:13 pm

I've heard T6 frequently mentioned also, apparently it still has the good stuff in it that the government made the gas engine oils take out for emissions.

From what I gather zinc content is pretty crucial for when the oil molecules start to shear and break down.

Sounds like that's probably what i'll use then, it's easy to find also.

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

T6 is cheap and available. It's even good for motorcycles!

Go fast guys with built motors start to have oil pressure issues near the end of a 20-30 minute sprint race, so they'll buy the unicorn AMSoil stuff.

Vincent Keene · **Posted:** Wed Jan 13, 2016 3:40 pm

Andrew Jonell wrote:

Go fast guys with built motors start to have oil pressure issues near the end of a 20-30 minute sprint race, so they'll buy the unicorn AMSoil stuff.

I guess we're slow, maybe because we don't have a "built motor"? We've run Rotella T6 in our Lemon's cars since 2009 and have had zero oil pressure issues even with oil temps as high as 280F.

Jordan Normark · **Posted:** Wed Jan 13, 2016 5:07 pm

I also use T6 in the Miata with a little ZDDP additive.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

T6 in (almost) everything, street and track.

25,000 race miles on the engine in Simon, all with T6

FWIW - my layman's understanding of why T6 is good:
- T6 has high zinc levels
- Zinc tends to coat bearing surfaces and creates a sacrificial wear surface, extending the life of surfaces
- Zinc was found to clog cat converters in cars that tend to burn oil
- High zinc was outlawed (?) or removed from regular car engine oil formulas to not clog converters but remains in "diesel oil"

Net is, don't use T6 in a car that burns oil and has a cat.

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

Vincent Keene wrote:

I guess we're slow, maybe because we don't have a "built motor"? We've run Rotella T6 in our Lemon's cars since 2009 and have had zero oil pressure issues even with oil temps as high as 280F.

The Mazda B series motor has Iron Duke levels of racing pedigree. The BP doesn't want to spin or flow, and specific outputs for naturally aspirated builds have a horrific looking $/hp/reliability ratio.

Rotella T6 is fine for 99.9% of us out there; however, it's the top level Spec Miata or the guys who dominated NASA's PTE/PTD/PTC fields out west who seek out unicorn tears stuff.

Chad Culbertson · **Posted:** Thu Jan 14, 2016 11:31 am

Andrew Jonell wrote:

Vincent Keene wrote:

I guess we're slow, maybe because we don't have a "built motor"? We've run Rotella T6 in our Lemon's cars since 2009 and have had zero oil pressure issues even with oil temps as high as 280F.

The Mazda B series motor has Iron Duke levels of racing pedigree. The BP doesn't want to spin or flow, and specific outputs for naturally aspirated builds have a horrific looking $/hp/reliability ratio.

Rotella T6 is fine for 99.9% of us out there; however, it's the top level Spec Miata or the guys who dominated NASA's PTE/PTD/PTC fields out west who seek out unicorn tears stuff.

Do they run high lift cams and such in those? I know in the Camaro world guys would go crazy over oils, especially the ones running high spring rates on the valves.

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

Nah, stock cams.

Spec Miata is Spec Miata; everything's written to the rulebook and everything is machined or matched to the absolute limit of the factory specs. An already built Spec Miata will cost you around $10k, a front runner starts at $35k or $40k.

For the PT* stuff, Emilio from 949Racing looked at the rulebook and did a bunch of development. Before 2010-2011, the consensus was that the VVT motors were junk; however, aftermarket ECU standalones started to really pick up and be incredibly robust. The formula they used was a "0 point engine build" starting with an 01-05 motor with head work to allow oversized valves and shim under bucket setup while using the stock cams. The bottom end received better connecting rods and slightly higher compression pistons to make the 1.8L (1839cc) into a 1.9 or 2.0L motor that can spin safely up to 8000rpm.

These cars had dyno plots that looked like this:
Dyno reclass - http://949racing.com/enduro/020613_130whp_dyno.jpg
Points based - http://949racing.com/enduro/143whp_E85_idealPTEmap.jpg

Go look up the Tracktuned/SlipAngle podcast with Emilio from 949 (and Andrew from TSE is a mini 10 minute episode) for a brief oral history if you'd like to know more.

Steven Carter · **Posted:** Thu Jan 14, 2016 2:07 pm

http://www.bobistheoilguy.com

Have you sent a sample to Blackstone labs to see if there are problems with current oil?

JamesMilko · **Posted:** Thu Jan 14, 2016 3:56 pm

The picky oil in Miatas is the transmission. There are two good oils. AMSoil MTG and Motorcraft MTX (XT-M5-QS).

The Miata transmission is on paper rated for GL-4 or GL-5, but it isn't super happy with GL-5 oils. I've run those two, Mobil 1 GL-5 and MT-90. The AMSoil and Motorcraft shifted way better than the others. There is oil analysis on MT.net showing the MT-90 is junk.

Jordan Normark · **Posted:** Thu Jan 14, 2016 7:13 pm

JamesMilko wrote:

The picky oil in Miatas is the transmission. There are two good oils. AMSoil MTG and Motorcraft MTX (XT-M5-QS).

The Miata transmission is on paper rated for GL-4 or GL-5, but it isn't super happy with GL-5 oils. I've run those two, Mobil 1 GL-5 and MT-90. The AMSoil and Motorcraft shifted way better than the others. There is oil analysis on MT.net showing the MT-90 is junk.

Off the top of my head, I think I have MT-90 in the diff and MTL in the trans. I can say the trans shifts better with MTL than GL-5, especially at colder temps. I've never tried AMSoil or Motorcraft.

Patrice Bousquet · **Posted:** Fri Jan 15, 2016 7:59 am

Jordan Normark wrote:

Off the top of my head, I think I have MT-90 in the diff and MTL in the trans. I can say the trans shifts better with MTL than GL-5, especially at colder temps. I've never tried AMSoil or Motorcraft.

We use the same in our Miata, when i put the MTL in the trans. it shifted much better when cold.
We used T6 in the engine, the hydraulic tappet are much quieter with it.

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