DansBlkonBlkZ06

I've only been tracking for less than 2 years and am now seeing my oil temps get higher as I'm running harder on the track. I'm approaching 290 degrees and have been using the standard 5W30 Mobil 1. I've read threads where many are using 15W50 for track events. This oil seems a bit thick to me. I've heard where some are mixing the two oils, but that would seem to be similar to a 10W40. Is anyone running Mobil 1 10W40 at the track? Since I drive dual street/track, would mixing be a better option? Thanks for the feedback.

froggy47

When it's all said & done, your best bet will probably be an upgrade radiator w/cooler. Others will chime in on various oils & weights.

CorvetteZ51Racer

I agree with upgrading the cooling. The issue at the temps you're seeing isn't the viscosity of the oil, but the life of the oil. At those temps, even some of the best synthetics will start breaking down quickly.

FWIW, I see ~260 oil in my Z with the stock cooling in Texas during the summer, and I run Valvoline VR1 Racing 15w50. At these temps, the 50W is similar in viscosity to a 30W at normal temps, and the VR1 Racing has a high molybenum content for additional lubrication. The Mobil 1 Racing oil (20w50 I think) has a similar formulation.

John Shiels

If you want to know your oil have it tested for 25 bucks. That will tell you exactly what is happening to the oil AND you motor wear.

I was running my car with 10/30 Mobil and was told I could go 4,000 track only miles. My car does not run that hot any more because of coolers and better air intake but testing is key. Before I did the coolers and stuff I saw 310 but then one day BAM!

travisnd

15w50 is like molasses... I've run 10w40 Amsoil for years. IMO it's the ideal oil for tracking a LSX motor that isn't custom built for 15w50 type oil. You can get 5w40 Mobil 1 which is similar too.

jlutherva

Three of the four events that I ran last year were around 100F. I ran a 50/50 mix of 10W-40 and 15W-50. I tend to control the temps by using 5th gear on the straights when the oil temp goes over 285 or so. For the cooler track day, I used 10W-40 and that's what I use for the first event in April at VIR.

At the NCM VIR event last year, an engineer from Mobile 1 gave a talk on oils. He recommended 15W-50 for track use and a max of 1000 track miles.

Jim

Jason

Get an oil cooler.

AU N EGL

15W50 is like molasses when cold, but at 250* the viscosity and anti- wear is perfect.

the 5W40 will work well for a street semi track car.

and as John Mentioned get the oil tested every few changes.

travisnd

5w40 and 10w40 work fine in race cars too... never had an issue. Wallyman has been running 5w30 Mobil 1 in his motor for years and years and beats the snot out of it on the same old LS6.

Every car I've run 15w50 or 20w50 in shows increased oil pressure and increased oil temps even when up to full temp.

If you read BITOG at all you'll see that the move to realy thick oil for race motors in hot weather isn't always the best option i.e. oil pressure doesn't always = lubrication. Those guys can argue about it for weeks on end so at the end of the day pick what makes you feel good and run it.

waddisme

Ran Amsoil 20/50 for past 2 years, but oil temps still got 290*+ even with oil cooler. That is with an aluminum H/C/I 402. Switched to 10/40 for this year. Curious to see difference. Going to VIR next Monday w/10/10ths but probably will not be warm enough to tell yet. I thought about putting a bigger oil cooler, but was suggested to try thinner oil. I will post what I find.

MJM

I ran a C5 Z06 for years with Mobil 15w50. 300 degree engine oil temp was not uncommon during the summer at VIR.

Now I have a C5 FRC that I have run for years with Mobil 15w50. 300 degree engine oil temp not uncommon at Willow Springs in the summer. After a few years of doing this I installed a DRM / Ron Davis radiator and oil cooler. Temps are lower now.

The engine oil / max engine oil temp question gets asked every so often on this forum. Different people have different opinions and some feel very strongly about them.

Personally I think you can run 15w50 up to 300 and still be safe. The only reason I installed the cooler was because I got tired of backing off every 4 laps to get my temps below 300.

AU N EGL

Lower oil temps helps keep the block cooler too.

TheKomoman

I don't know enough to offer my own opinion but I'll share what came from the "horse's mouth" last year at NCM VIR. The Mobil 1 folks were there and the guy that spoke to the class I was in STRONGLY recommended their 15W-50 if you're seeing 250 or higher temps. His primary focus was on shearing and the concern that after seeing temps consistently above 250 the standard 5W-30 may not thicken back up after cooling due to shearing. Yes he's a Mobil 1 guy and it was certainly part of his job to sell it but he was strictly comparing the different weights of Mobil 1 and he was pretty darned convincing.

froggy47

Hmmmm. Interesting.

froggy47

I know you can cycle between them, but which display would be the best one to leave on when you are done cycling>

Temp?

Pressure?

jlutherva

I use oil temp on the DIC and watch pressure on the HUD, but only on the straights.

Jim

Zenak

Did you read the stick in this section that covers this and more:

http://forums.corvetteforum.com/auto...e-learned.html

C66 Racing

There are two main issues with running Mobil 1 5w30 and you touched on one - viscosity. The other is anti-wear additives.

Viscosity.

The LSx engine was designed for an oil with a viscosity of about 10-11 cSt, which is what a 30 grade oil is at 212F - a 30 grade oil is defined as an oil having a cSt viscosity of 9.30-12.49 at 212F. At 300F, a typical 30 grade oil will have a viscosity of only about 30% of that value. Mobil 1 5w30 viscosity at 300F is 3.13.

There are two ways to address this. One, run a higher grade oil and two, add an oil cooler. The latter approach is the better option. A 50 grade oil has a viscosity of 16.30-21.89 cSt at 212F and typically has viscosities of 4-5 cSt at 300F, still well below that of a 30 grade at 212F, but about 33-66% higher than that of a 30 grade at 300F. Mobil 1 15w50 has a viscosity of 18 cSt at 212F and 4.5 at 300F.

But there are downsides to running an oil with that high of a viscosity including higher pumping losses, increased internal friction which drives up heat, and lower heat removal by the oil which also drives up heat.

A 40 grade seems to be a good compromise for a track day car without a cooler and maybe many that do have coolers. 40 grade oils have a viscosity of 12.50 - 16.29 cSt at 212F and typically have viscosities around 4 cSt at 300F. Mobil 1 0w40 has a viscosity of 13.5 cSt at 212F and 3.8 cSt at 300F. Due to their higher viscosity than a 30 grade, they will maintain film strength better at high temp high shear than a 30 grade and due to their lower viscosity than a 50 grade, they will have lower friction losses and will remove heat better than a 50 grade in typical heat ranges experienced by an LSx engine at the track.

Anti-wear Additives.

With the previous generation of oils, the API limited the amount of phosphorus in automotive oils to 800 ppm for 30 grade oils, down 20% from the previous generation and down 33% from the API SH spec which was in effect from 94-97. The API did this to prevent long term damage to the cats so the auto manufacturers could meet EPA requirements for 100k + mile emissions requirements as phosphorus carried through the exhaust due to oil burn off slowly builds up in the cats and minimizes their effectiveness. Unfortunately, phosphorus, along with zinc, in a compound called Zinc dialkyl dithio phosphate or ZDDP, form an oils main anti-wear additive.

So by running an off the shelf API SM 5w30 (as recommended by GM), you are running an oil with a viscosity too low for the track and one with much lower than historical anti-wear additives.

So what to do?

Many dual use cars use an oil such as this one as a compromise:
AMSOIL SAE Synthetic Premium Protection 10w40 (Product Code AMOQT)

This oil does not meet GM owner's manual requirements, thus isn't recommend by AMSOIL which only recommends oils that meet the owner's manual requirements. But, it does provide more viscosity protection than a 30 grade with a viscosity of 4.3 cSt at 300F, almost has high as M1 15w50, has the proper detergents and dispersants for dual use track/street car, and has high levels of ZDDP (zinc – 1378 ppm, phosphorus 1265 ppm). Running an oil with a viscosity over that of a 30 grade will require an good oil warm-up. My personal thumb-rule is 150F before using high rpm or more than part throttle.

The other alternative is to run a true track oil (particulary in cars with oil coolers) :AMSOIL Dominator Synthetic 10w30 Racing Motor Oil (Product Code RD30QT)

This oil runs high in the 30 grade band, just below that of a 40 grade and has a viscosity of 3.6 cSt at 300F. In my car, I get slightly lower oil temps running this oil over the 10w40 mentioned above with my oil temps at about 255F at Watkins Glen last summer in July. This is right at the top of where I feel comfortable with a 30 grade oil.

It also has very high levels of ZDDP (zinc – 1575 ppm, phosphorus 1474 ppm) - but like the 10w40 above, doesn't meet owner's manual requirements and unlike the 10w40 above has no detergents and no dispersants so isn't really a good option except for dedicated track day cars.

ptindall

DRM/Ron Davis rad w/oil cooler is easily the most effective mod I've ever made of any type. However, after reading this thread I guess I'll be changing vescosities in the future. I've been using 5w-30 with no problems and good oil pressure, but I guess I'll be going thicker now.

C5_Z06

Interesting input. Where did you get that info, or is it an assumption based on GM's 5W-30 recommendation?