l8_apexer

I did a search on this- and not being a PHD Petroleum chemist, I found the information to be a bit overwhelming to what seems to be a simple question.

With a fresh change of Mobil 1, 5-30, while heading to an event, the car registers 30mpg.

Nice time at the event, no hard revs, oil temps moderate (none higher than 266 degrees).

Trip home, (same speeds, similar weather, same route), MPG has fallen sharply to 24mpg. The first time this happned, seemed to be an anomaly. The second time, tells me that the oil is losing its lubricity-- and gives rise to the concern that 5-30W isn't the right protection.

Other cars (and race cars owned in the past) we've always run 20-50w or a 40w racing oil.

What should an LS3 be running in a De environment?

Anyone know what Bondurant or Spring Mountain use in their fleets?

thanks

AU N EGL

5-w30 is just fine.

if or when your car becomes a dedicated DE car or race car then 40wt racing oil or 5-w50.

a fresh oil change is a good idea before any event

I do run 15/w50 myself

But to start out, just use what you are using. keep the oil temps down and have fun

GettReal

Ive been running 5/50 or 15/50 (mobil 1). The heat these cars see on a track, the oil will thin out quite a bit. My car has bad enough issues with ring blow by so adding the extra wt will help. And yes, changing often is cheap insurance.

rustyguns

15/50 here!

wtknght1

15W-50 is what GM told me to run.

And, OBTW, don't run that car on track unless you have the alternate oil pan #12630477. That's free friendly advice. ...the oil pan however ain't!

lbarnard

An accusump is good insurance when you track the car. I run Lubrication Engineer (LE) 15/40

C6400hp

Tell us more about the oilpan, LS2 compatible?

wtknght1

The new pan is similar to the LS6 gull wing pan - holds a few extra quarts, better baffled, and ensures the oil pickup actually has oil to pick up! I'm 99.9% sure it'll work on the LS2 as well.

I'll be selling my LS3 some time next year to drop a new one in for the Runoffs.

EvilBoffin

OK, Chris - explain yourself here - does this mean you are selling your LS3 OILPAN, your LS3 MOTOR or your LS3 Vette >!?@#!?

Inquires minds want to know...

wtknght1

Yes sir.

I'll be selling my LS3 ENGINE and the attached gull wing oil pan.

C6400hp

I can't find any of the normal places lilsting that part number for anything. do you know where I can find out more info? Pricing? Availability?

wtknght1

Bob Herbers at GM is a good place to start: 810.239.4122

Cobra4B

My '01 was an oil burner... after my re-ring in early 2004 I started using 5w40 amsoil and have been ever since. I've run many HPDEs in the car, it uses about 1/2 quart between DIC specified oil changes, and still makes 430+ rwhp with 80,000 miles on it (re-ring was at about 30k).

Not sure why you'd get that much less MPG on the way home, but I doubt one HPDE weekend with oil temps in the 260s would phase Mobil 1 at all.

sperkins

You are referring to instant MPG and not average right?

I seriously doubt that the oil has lost enough lubricity that it is causing that much of a MPG change. That would mean the friction coefficient in the engine has gone through the roof - probably so much that it would seize. I would guess the problem is more so in what the computer is doing. Remember that on the track, the computer is dumping a ton of fuel to keep everything cooled down. Maybe it's in limbo mode after you come of the track for at least a little while.

C66 Racing

This is a very complicated question.

First, my thoughts/comments on your loss of mpg. Did you reset the calculator after driving on the track? Assume you did, but if not, the low mileage on the track is probably skewing your average home. If not, then I'd agree that your oil is shearing down fast and you are seeing increased internal friction. Are you seeing higher oil temps on the way home?

As to the question on what oil to use, here are some thoughts.

Viscosity. I believe that your choice of viscosity should be based on your oil's hot track temp. All oil's viscosity drops like an exponential decay as its temp increases. As an example, and taking data straight from the manufacturer's websites, Mobil 1 5w30's viscosity is 64.8 cSt at 100F, 11.3 at 212F, and 3.09 at 300F. The engine was designed to operate near 212 and thus the recommended oil has a nominal viscosity of about 10-11 cSt at this temp. But, if on the track, your oil temp is significantly higher than the the nominal 5w30, the oil's viscosity is very very low. This is why many guys tend to use and recommend Mobil 1 15w50. From Mobil's website, their 15w50's viscosity is 131.2 at 100F, 18.1 at 212F, and 4.5 at 300F. As you can see, this oil has a pretty high viscosity at 212F compared to the factory fill 5w30, but if your oil temp is around 270F or so, its viscosity is much nearer the nominal 10-11 cst than that of a 5w30.

I've run a 5w30 in my car at track days and found the oil temp went upwards of 300F. Added an oil cooler but still had oil temps upwards of about 280F or so. Went to 15w50 as recommended to me by more experienced racers and oil temps stayed about the same, but I felt better with the higher viscosity and my oil pressure was up significantly. But, when I switched from Mobil 1 to AMSOIL, I tried their 10w40 and found my oil temps dropped about 30F to around 240-250F. At this temp, I feel that the 10w40 is the right viscosity for me. My rough rule of thumb is oil temp <240F, use xw30, oil temp 240-270F, use xw40, oil temp > 270F, use xw50.

Additives. The primary antiwear additive in autmotive oils is ZDDP, or Zinc dialkyl dithio phosphate. The new API SM/ILSAC GF-4 specification limits phosphorus to 0.08% or 800ppm in 30 grade oils, which effectively limits the amount of ZDDP the oil can have. This limitation was put in place to provide long term protection to the catalytic converters as the industry has found that phosphorus tends to reduce the effectiveness of the cats. Note that these limitations don't apply to 40 or 50 grade oils, nor do they apply to racing type oils. For example, the AMSOIL SAE Synthetic Premium Performance 10w40 I used has phosphorus on the order of 1265 ppm and zinc on the order of 1375 ppm. Mobil 1 15w50 has 1200 ppm phosphorus.

Basestock. Since we're talking oils, we should consider basestock. The term "synthetic" has not been defined by the API and three groups of oil can be advertised as "synthetic". Group III, highly hydroprocessed mineral oil, Group IV, polyalphaolefins (PAO), and Group V, chemically engineered stocks that do not fall into any of the categories previously mentioned and includes esters. Historically, Mobil 1 used Group IV, but about a year ago their website became non-commital on the subject and from reading the oil forums, the common belief is that Mobil 1 went the way of most other "synthetics" and now uses a blend of Group III/IV basestocks. AMSOIL uses Group III in its XL line and Group IV in its other lines. Red Line uses Group V.

Warranty. Might not be an issue for too many C5s these days, but for those that are, and for the C6s, the owner's manual requires an oil meeting GM Standard 4718M. To meet this standard, an oil must be a 30 grade oil, and must meet API SM standards (noting that the standard when the C5 came out was SL which didn't put limitations on ZDDP). Thus if you want to track with oil meeting GM Standard 4718M, you must use a low ZDDP 30 grade oil - I don't feel that this is the right choice.

This summer (while I was deployed), AMSOIL came out with a true racing oil line, but only in 15w50 and 10w30 grades. While these are racing oils, they have a Total Base Number (measure of the oils resistance to acidic buildup) of 8.0 so they are suitable for limited street use (not an extended mileage oil which needs a very high TBN). I ordered a case of the 10w30 but haven't tracked with it yet. I intend to try it and see what my oil temps are. If they are too high, I'll go back to an AMSOIL Premium Performance 10w40 or maybe their Marine Motor 10w40 which is another high ZDDP formulation.

Recommendation for you, try used oil analysis. If your oil really is failing (and leading to increased bearing wear), better to know now vice later. Here's an example:
AMSOIL 10w30 Used Oil Analysis

C6400hp

Anyone using this new oilpan on an LS2 with LG headers or any other headers for that matter? Concerned about clearance issues with the new pan.