track bumb

I spun a rod bearing in my 07 Carrera S last year at Thunderhill. Neillo pointed out to me that running anything other than street tires could cause oiling problems leading to catastrophic engine failure. Even though I had R compounds on the car they let me slide and honored the extended warranty. I later found out in reading the manual than race tires should not be used for tracking the car. The same goes for the new Porsches except for maybe the GT3 that I'm guessing has a dry sump. Why would Porsche put such a crappy oiling system in a car that a lot of folks like bought to track? I have since put the street tires back on and use it for a grocery getter untill I sell it. Buyer beware.

333pg333

Most M1 is crap for track cars. Oils with wide range like a 5w/50 is a marketing scam. 270f is crazy high. Good luck. :-)

bpu699

So whats good for a track car, that's readily available?

VR1 conventional is good, right?

VR1 synthetic any better? I see the conventional recommended more (less leaks).

Heard mixed things about Brad-Penn...

Amsoil and redline aren't easy to get...

177mph

So you want an oil recomendation for your car? I wonder if rennlist has any threads on that subject?

fatbillybob

I think I have one of the few intelligent solutions. I discussed this with a mobil 1 tech/engineer at Runoffs once and he looked at me with glazed eyes so maybe I'm insane but here it is what do you think? For the record my motors seem to last longer than so far anyone else in my local group racing the same classed corvettes. Oil brand and past favorites or that of an engine builder seems to be what is used by most. There seems to be no scientific reason for those selections. What I do is look at the oil temp of the streetcar in is operational range as a streetcar. So lets say my owners manual says use 10-30 mobil one. You find the operational oil temp as a streetcar is 220F. I am assuming the car is designed and oils selected for the operational range. Looking at the oil viscosity of 10-30 at 220F is say around 11cst. So if I'm racing my street motor at 280F for 11cst viscosity I would need to run a 20-50W oil so that's what I did for years and my motor never blew it just finally became non competitive. Then I went to a huge radiator and oil cooler seeing no more than 240F and went back to a 10-40 oil. IMO the viscosity at operational temp was more important than the brand. The caveat to that is running a 20-50 on a motor designed to be started and instantly run with 10-30 I was careful to warm the motor before banging on it.

mark kibort

maybe that is becuase two things happen at the track.... you were running an oil that broke down viscosity wise at track temps (do you have oil temp or pressure readings?) and the sticky tires created enough g loading to remove oil from the pick up, OR the oil started to foam which has the same effect, and that is regardless of g loading

ive been racing an engine that is known for blowing rod bearings at the track, most on moble 1..... with redline or amsoil, ive raced on huge DOT rubber and Pirelli slicks (and hoosier slicks) wiith NO issues for ...........................
over 250 race hours!!!!!! over a 20 year period. one motor for 120 race hours and the other up to 80 race hours and my first engine 175,000miles and 50,000miles of it was on the track

mark kibort

VR1 was the same results at the track as mobil 1.. bad. very low oil pressure when hot. redline and amsoil and im sure others are good too. (motul, bradpenn, etc)

amsoil you can calll and order .. they ship..... $14 bucks a quart non member, 10 bucks a quart member. membership is 20 bucks , so with first order of 4 gallons , you break even on the first gallon. cheap insurance in my book

good point about what happens AT the track, but here is some kind of cientific study at the track. mobil 1 was turning on the oil pressure warning light and redline didnt. multple cars. 5 bar running at tract temps vs 3 bar and less with mobil 1 and VR1. all were 20-50 or 15-50.

I just over heated due to radiator or water pump failure this weekend, and oil temps went to 270F range..... oil pressure was also failing down to 3 bar, which i never ever see. so i backed out on the turns with lower RPM and basically went 50% effort for the last few laps of the race . seemingly saved the engine. the gauges are there for us to get valuable info on the engine running condition and the oil performance. if it cant handle full pressure at 260f range, you need another oil. Mobil 1 doesnt keep pressure at high temps, but maybe in some cars this isnt a problem. it is in a 928

the_vetman

Important to remember.

Dr.Bill

Add a PDK cooler. The PDK cars run much hotter than the 6-speed cars.

Also, I'd check the radiator grill mesh. I put some on my Cayman R and just the little bit of airflow disruption caused it to run hot. Removed the mesh and added some water wetter to the coolant and no more problems.

ProCoach

I've run into this a fair bit when people add oil temp sensors in the pan or at the exit of the engine (scavenge side of the pump in a dry sump system). Oil temp coming out of the engine is not particularly important other than to measure the efficiency and effectiveness of the cooling and de-aeration of the oil before it goes back in. The compression of the bearing loading can raise the temperature coming off the radius of the rod journals to in excess of 300 degrees, in the most severe cases. Think pressure cooker and pressurized cooling system physics...

The key performance indicator (and the only measure that matters, IMO) is temp going into the main supply galley, or the passageway or fitting closest to the direct supply to the crankshaft. THAT is the number the better engine builders are keen to know... and 230 on an air cooled car is about the upper limit, AFAIK. More on the water cooled cars.

Heck, I'm an old Italian car mechanic (don't miss it, either) and with MB1 15W-50, I didn't worry until I saw 280+! ��

mark kibort

yes, there is some cooling as the oil comes out of the bearings, but not a lot. remember, this is not "pressure cooker" physics for all practical purposes, the compression and temp rise only works for gasses, not incompressible fluids!
The reason that there is oil pressure is to provide a heat sink for the engine moving and static parts, as well as to provide lubrication. it flows relatively fast, so it finds its equilibrium temps and preserves its viscosity. i measure oil temp as its coming directly off the crank and pistons and those temps are near 260F in extreme racing conditions on a hot day. its a pretty good indicator of the oil's condition and its abitlity to protect moving parts, as seen by the complete viscosity "melt down" at temps at 270+.
sure, some engines are designed to handle thin oil, just as some engines can run 30 weight and dont need 50 weight oils. But make no mistake, if you are trying to protect moving parts in the engine you want to use an oil that does the best job of protecting the engine at temps

ProCoach

Mark, while oil does serve to "wick away" some heat, the primary purpose of oil is to form a protective film between moving metal parts! If that film is interrupted, then the film disappears and metal touches, with catastrophic results. A dimensional change in the area between the two metal surfaces can cause a pressure loss or bring areas of the minor diameter of the rod into contact with the journals on the crank, but as long as the pressure and critical dimensions are maintained, pretty much any recognized oil can be used without harm. I like synthetics (over dino oil and parasynthetic blends) because of their resistance to aeration, heat and foaming breakdown. YMMV.

mark kibort

yep.. im with ya there. its that protective film that can get compromised at high temp though too. so, the reason for the viscosity is for the film qualities as well as making sure there is a film there!
I think what i have seen with my car, which is characteristically very prone to rod bearing failures, is that the anti foaming qualities of redline/amsoil have proved to solve a weakness of the engine design at high RPM and high g loadings.
so, any oil might do, if it didnt foam and have viscosity break down.... so i guess any oil WONT do !

Matt Romanowski

My experience is similar to Peter's, but a little different. I did a lot of research and talked to oil engineers at a number of companies. 300F out of the bearings is not abnormal. The limit there should be around 325F. Temps on the feed (out of the oil tank on a dry sump motor) should be south of 265F.

A general rule is that you will lose around 30F across most coolers.

There are certainly differences in oil and IMHO, the answer is always synthetic. From there, lots of different oils are high quality and will work well. It depends on a lot of factors including pressures, bearings clearances, bearing width, oil aeration, etc.

fatbillybob

Oil testing that tells you if what you are using is working at whatever the operational temps are.