sydneyACE

I have a HPDE event coming up here in a couple of weeks. Last year I was seeing high oil temps 300+. I know the obvious answer would be to get an oil-cooler set-up, but it's just not in the budget for this one (after new tires and stuff).

I have been through LOTS of threads on here (and other forums) about "the best oil" and obviously there is no right answer.

Some folks have said they use Rotella T6 5W40 with good results and it has a ZDDP content of 1200ppm.

They have it down at wally world for $20 a gallon, so the price is right.

I was hoping the 5W40 would protect a little bit better at that high temp although after doing some reading over at "bobistheoilguy.com" it seems like his opinion is that higher viscosity makes almost no difference at that temp level.

Just looking for some input if any of you guys have run it.
Thanks!

rmackintosh

I ran it for a year in my MAST Motorsports LS7--it was the oil they wanted me to run above all others. One year of use, about 8 track weekends with a 4 stage ARE dry sump. Made it real easy to change the oil on that sucker given the amount of oil a change took. Was nice oil and seemed to work well.

Black89Z51

I use this stuff in my turbo diesel truck. I believe AMSOIL did a comparison with their oil and the T6.

Kubs

For a street car I would recommed staying with a 30W oil. Amsoil just released a new product line called Z-Rod. It contains high levels of Zinc (about 1500 ppm) and Phosphorus (about 1400 ppm), but also contains the detergents required for street use.

http://www.amsoil.com/storefront/zrt.aspx?zo=1934716

A 40W oil may actually cause more friction in the engine which will increase operating temps due to the tight bearing clearances in modern engines. Just something to think about when selecting oil.

Black89Z51

Subdriver put up a very good post(s) about oil viscosity a few weeks ago in this section. Try giving that one a shot. It's a damn good article imho.

rfn026

40w is going to create friction and heat. You don't need 40w and your car will run cooler with 30w.

Richard Newton
Vintage Motorsports Magazine

C66 Racing

Diesel oils have a lot of detergents and dispersants that you don't need in an automotive oil, and don't particularly want in a track day oil. Assuming your car is dual use street/track and you do need some detergents and dispersants in your oil (as opposed to the about none in the racing oil I use), I'd consider these two depending on your viscosity decision:
AMSOIL Z-ROD 10w30 Synthetic Motor Oil (Product Code ZRTQT)
(zinc and phosphorus high, but don't have exact numbers yet)
AMSOIL SAE Synthetic Premium Protection 10w40 (Product Code AMOQT)
(zinc – 1378 ppm, phosphorus 1265 ppm)

For any interested in trying either of these, I'm happy to get them for forum members at dealer wholesale, about 25% below retail via the AMSOIL Preferred Customer Program. Drop me a PM if interested.

Sidney004

Its temperature dependent, at low oil temperatures, you are absolutely correct, but at 300F it is not significant:

TEMP F 200 -- 220 -- 240 -- 260 -- 280 - 300
(vis
cSt)
10W-30 11.7 - 9.3 --- 7.6 -- 6.3 -- 5.1 - 4.5
15W-40 17.6 - 13.9 - 11.2 - 9.2 -- 7.3 -- 6.2
20W-50 21.5 - 16.6 - 13.1 - 10.5 - 8.3 - 7.0

Rob Willis

I think I've seen this SHELL 5w40 in 55gal drums shrink-wrapped on pallets at SAMs wholesale club.

Wonder if they sell it that way?!

sydneyACE

Yeah, I've been going crazy cause I've heard it both ways.
I realize that a higher viscosity oil (40vs30 weight) will cause higher temps, but I was under the impression that the 40 weight would protect better at those higher temps.
When I was running the Mobile1 5w30 last year my oil pressure seemed to be too low. I don't know if it was "really" too low, or just lower than normal.
I read on another forum that having high pressure wasn't important, it was FLOW that was the critical factor which also make sense. I'm just very concerned that 310+ degrees is too hot (for a 30 weight) and I'm seeing like 10psi (ish) at idle when it gets that hot. I don't remember what kind of PSI I was seeing at high RPM but I remember thinking its seemed too low.

I know oil has been discussed to death here, but I was hoping someone could help me out: 5w30 or 5w40? I like the Rotella because it has high zddp (zinc, phosphorus) content, which I hear is the critical friction reducer. I haven't found another oil in the same price range that has that high zddp content.

I think the Amsoil sounds pretty good but to be completely honest, I'm pushing my budget as it is and I can't afford 10qts of that, and if the Rotella does just as good of a job...

Will the 40 weight make things worse or better? Should I just run a 5W30 and get some ZDDP addative? Just run a 5W30 and shut-up and quit worrying?

Sidney004

My vote is for the Shell Rotella T6 5W40 .

rustyguns

I disagree....mine runs 290 with 30 weight and 290 with 50 weight

your not going fast enough

Rotella is used by a lot of race car drivers. it is very good stuff !

very big bang for the buck

rustyguns

it will save your main bearings and cam bearings

FYI you will lose 3 to 5 horsepower vs 0-20w racing oil

but they rebuild after every race

C66 Racing

Flow is important at removing heat, but fluid film strength is more important at protecting your bearings. At low oil pressure, your film strength will be lower. When your fluid film is gone, then ZDDP plays a critical factor. Compared to an API SN off the shelf oil, the Shell 5w40 will be better in both those areas. Compared to other options more specifically designed for this type of application, it will be worse.

One thing to watch should you choose to go with the Rotella is its shear stability, which is pretty poor compared to other diesel oils on the market. In the below link, an AMSOIL brochure for their CJ-4 Diesel 5w40, the graph on the second page shows that the Rotella starts with a higher viscosity than Mobil Delvac, Chevron Delo, and Valvoline Premium Blue Extreme, and after the shear test, has the lowest. You should be able to see this as a loss of oil pressure as the oil ages and use that drop as a guide as to how often to change it.
Diesel Oil Shear Stability

Oil is an area I will not look to save money. Having lost an LS6 my first season (2003) due to seized bearings on #3,4 piston rods, and having to pay the $7k or so total bill to buy the new engine and install it, a few more dollars on the right oil is well worth it in my mind.

Pumba

I agree with Sub Driver. Oil is something I never skimp on.

When I learned and understood the defiencies of the LS oiling system, I did everything I could to improve their system. Look at what happens to the Gen III and Gen IV oil pump performance at rpms over 6,200:





Look at the viscosity of any 30 weight oil at elevated temperatures versus a premium Group IV or Group V synthetic oil.

rustyguns

quote: Look at the viscosity of any 30 weight oil at elevated temperatures versus a premium Group IV or Group V synthetic oil.


How?

Sidney004

I don't want to put words in his mouth but what I think he was trying to say was that a premium Group IV or Group V synthetic oil contains less VI improver and is less subject to viscosity breakdown after being used at elevated temps and high shear conditions. Assuming it has not suffered viscosity breakdown all 30 weight oils whether Group II,III,III+,IV or V will have the basically same Viscosity v. Temp curve within the SAE engine oil grade range. There is a tolerance range so you might get some 30 weight oils that are closer to a 40 weight and others that are closer to a 20 weight, but that is independent of what Group type it is.
http://www.bobistheoilguy.com/viscosity-charts/

http://www.bobistheoilguy.com/viscosity-calculator/

sydneyACE

Thanks again for all the input guys!

I'll see how much $ I have left over after buying rotors, then go with what I can get.

I think I'll just bring my tent to the track, that will save all kinds of $ on a hotel hehehehe!

The event is this weekend, so I'll let you guys know how it goes.

Pumba

It is true that if you are checking the Viscosity Index of various 5W40 weight oils in a laboratory, they all will be similar. BUT, when these same oils, whether they are Group II, Group III, Group IV, or Group V, will show different V.I. results when run in a race engine at elevated temperatures and high loads. The Group II and III base stock oils will show a reduced Viscosity Index due to the fact that their V.I. Improvers -- Polymeric Thickeners -- have been broken down, sheared -- in high stress areas of the engine.

Your 5W40 oil may be a 5W25 with much lower film strength and thickness at the end of the race. This is because the Group II mineral oils and most Group III - *Rotella T6 5W40 - oils require a significant amount of these Polymeric Thickeners in order to achieve a 5W40 rating. It is these Polymeric Thickeners that are broken down-sheared in high stress areas of your race engine.

The Group IV Poly-Alpha-Olefin synthetic oils and especially the Group V Polyol-Ester synthetic oils - AMSOIL, Red Line, Delvac-1, and Motul 5100 require very few Polymeric Thickeners and they do not lose significant viscosity, film strength or film thickness during high load - high temperature usage.


* - Correction made - Group III+ base stocks are made from liquefied natural gas, called GTL (Gast-to-Liquid) base oils. These GTL base oils have natural V.I.s of 140 or more, meaning for most applications they won't require any Viscosity Index Improver package at all.

thehammer69

You must not be familiar with the Group-III+ XHVI base oil Shell now uses in T6. Plus there is no Group-II in T6. About the only relationship their XHVI oil has to lower groups is that it once was crude. It is processed and treated so thoroughly that the finished product really should be called a synthetic and will rival PAO's and Esters in performance.