Joe Gibbs Viscosity selection chart

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CATERHAM

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This is for their race oils but it does give the general relationship between required viscosity and oil temperature while factoring HP and bearing clearances. Scroll down to the bottom of the page:

http://www.joegibbsdriven.com/trainingcenter/learn/viscosity.html

Viscosity legend for their oils:
XP0 - 0W-5, KV 3.3cSt, HTHSV est 1.7cP
XP1 - 5W-20, KV 9.1cSt, HTHSV est 2.8cP-3.0cP
XP2 - 0W-20, KV 6.3cSt, HTHSV est 2.6cP
XP3 - 10W-30, KV 12cSt, HTHSV est 3.5cP

It's interseting to note that the XP1 5W-20 is the oil they run in their 800 hp sprint engines with typical oil temp's of 240C.
 
Originally Posted By: CATERHAM

It's interseting to note that the XP1 5W-20 is the oil they run in their 800 hp sprint engines with typical oil temp's of 240C.

Correction, that's 240F or 116C oil temp's.
 
Joe Gibbs site is good reading.
His oils are expensive, but excellent.
I wonder if normal Walmart bought oils fit in the chart's recommendations - it might be stretching things!.

Still, the concise chart shows a LOT of pertinent info.
We could practically do away with BITOG!
 
Originally Posted By: mechtech2

I wonder if normal Walmart bought oils fit in the chart's recommendations - it might be stretching things!.

His race oils are VI free and shear stable. Most street oils shear some so one might want to be a bit conservative on the viscosity front. Of course if you're maintaining adequate oil pressure there's nothing to be concerned about in running these light oils.
 
I'll also bet the Joe Gibbs oils don't contain SN levels of additives. That chart doesn't have any relevance to off the shelf street oils as far as I'm concerned.

Ed
 
I like the site.

The thing with lubrication is that increase the revs, and you need a lower viscosity, decrease the clearances, and you need a lower viscosity.

A typical DD will see lots of time at 750RPM (low load), then a period of reasonably low speed high(ish) load acceleration to some sort of moderate speed every minute or so with traffic and lights etc...Sprint will be cycling from 4,000-8,000RPM for tens of minutes at a time per "start"/movement...frequent OCIs, and frequent rebuilds comparatively.

Thinking it through, I'm more in favour now of my running 5W-30s in my DDs...start, 16 gear changes, 65MPH (2800RPM) for 10 mins, 5 gear changes, repeat backwards. To drive to nearest town, put 65MPH for 50 mins, and duplicate the gear changes each end.

It really is an easy job for the oil.

The chart is a little limiting, in that it doesn't describe how the power was obtained, how many cylinders, how big, how many bearings, what sizes and clearances.

And seems to contradict another sheet

http://www.joegibbsdriven.com/trainingcenter/guides/applicationguide.html

which defies the table, in giving what makes more sense IMO, that a crate motor is larger clearanced, rev limited, thicker oil. "Built" engines that are operated at higher speeds, with more consistant ability to move heat into the airflow are able to run thinner, as there is less variability in their operational regimes.
 
Originally Posted By: edhackett
I'll also bet the Joe Gibbs oils don't contain SN levels of additives. That chart doesn't have any relevance to off the shelf street oils as far as I'm concerned.

Ed


True.

But that isn't the point of the post and included link.

Just one aspect to be considered when chosing an oil.
 
Originally Posted By: edhackett
I'll also bet the Joe Gibbs oils don't contain SN levels of additives. That chart doesn't have any relevance to off the shelf street oils as far as I'm concerned.

Ed


I would have to agree. Also, racing oils have very few detergents added and are not suitable for street use. They also have over 2,000 ppm of zinc and phospherous.

And, a 800HP sprint engine has no working relationship whatsoever to a street/DD engine other than they are both IC.
 
Originally Posted By: Shannow

The chart is a little limiting, in that it doesn't describe how the power was obtained, how many cylinders, how big, how many bearings, what sizes and clearances.

I agree but it's a good place to start and it gets one thinking if you're using an significantly heavier oil than the chart would suggest as necessary.
A track buddy of mine with a race tuned Miata (230 hp) had been using a heavy 40wt and was very reluctant to try their recommended XP1 5W-20 although in reality it is likely a light 30wt oil. Anyway he did and was delighted with it although he has now switched to RL 0W-20 for the normal TBN levels and longer drain intervals.

As I always say, is you can maintain normal oil pressure then you're not running an oil too light.
That said, there are plenty of examples where even running the spec' oil can allow very low operating viscosities with the OP below spec'. One example is the Chevy Corvette ZO-06 (505 hp). The spec' M1 5W-30 with a virgin HTHSV 3.1cP but likely more like 2.9cP in service can withstand oil temp's of 260F without issue. OP will drop below the recommended 50 psi minimum under such conditions.
Another example are the Chrysler SRT8 V8s ( something like 400 hp), spec' oil PU 5W-40 HTHSV 3.6cP but likely 3.4cP
at best in service that can run 300F oil temp's without issue.
When you put those low operational viscosities in context, running a typical 0W/5W-20 in a vehicle on the street that may never see oil temp's even as high as 212F makes one wonder what all the fuss is about with light oils.
BTW, a 2.6cP 20wt oil will have a HTHSV at 100C of about 5cP. Obviously there's a hugh safety margin there.
 
Originally Posted By: CATERHAM
Originally Posted By: CATERHAM

It's interseting to note that the XP1 5W-20 is the oil they run in their 800 hp sprint engines with typical oil temp's of 240C.

Correction, that's 240F or 116C oil temp's.


Sprint Cup Car oil also only has to last for 150-600 miles under these conditions as well, at which point it is dumped regardless of how much life is left in it.
wink.gif


But, I see your point, and this link is good info.

Will you knock his 'shear-stable' oils for not having sky-high V.I.s though??
 
I've chatted with Lake Speed Jr and he's a very nice guy. Very helpful and forthcoming with info'. His understanding on how to optimize the oil viscosity for a given application he's very good at.
Having said that, yes I would prefer the higher VI M1 racing oils.
 
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