Use of heavy weight oil in racing applications. (WRX)

[Jeff Sponaugle]

I've been reading thru older posts on this board, looking for information about use of 50+ weight oils in racing application. As you can imagine, there is an abundance of posts that cover alot of the details, but getting a good summary is often difficult.

Here is my situation, and I would love to hear your guys feedback. I have a 2002 Subaru WRX, with relativly heavy modifications (about 480crank hp, 377 wheel hp from 2.0Ls at 24psi).

[see www.wrxworld.com for videos, etc]

I'm looking for a good oil to run, given then constraints of the car use. I drive the car on the street occasionally, but not every day. I race the car quite a bit in the summer months, and usually have 10-20 days of track time in by the end of the season. (road track racing, 20-30 min full throttle sessions). Oil Temps at on the track are right at 110-112 deg C, and crusing around town they are about 95C.

My primary concerns are good protection of the internals during hard use. I'm running a pretty large turbo, with 24+psi of boost, plus 100 octane race gas. I'm not really concerned too much about wear, as I will rebuild the motor within 30-40k miles. I don't mind waiting for the car to warm up before driving it, and the temperature here doesn't go below 32 except for a few days of the year. Change interval is not a big deal, as I usually change the oil once every 3-4 track days, which is usually about 3k miles or every 2 months.

With all of this in mind, it would seem like I would get better protection from a 15w50 or 20w50 synthetic oil. Most stock WRX guys run Mobil 1 10w30. The oil is also a factor for the turbo, since the engine oil is the primary lubricant for the turbine.

Any opinions on this kind of application? I would still be interested in doing some oil analysis after a race to see how things are looking of course.

Jeff Sponaugle

 

[Drew99GT]

**** , sounds like you got a BEAST there! What turbo are you running? Water cooled I'm assuming? If you want noticably better spoolup with a standard thrust bearing turbo (not ball bearing), stay away from heavier viscosities. I wouldn't go over 40 weight at all. For that kind of abuse on a motor, you may want to go with a redline single weight racing oil. You're probably encountering oil temperatures that would just cook most other oils, especially at the bearing in the turbo.

 

[Jeff Sponaugle]

quote:

---

Originally posted by Drew99GT:
**** , sounds like you got a BEAST there! What turbo are you running? Water cooled I'm assuming? If you want noticably better spoolup with a standard thrust bearing turbo (not ball bearing), stay away from heavier viscosities. I wouldn't go over 40 weight at all. For that kind of abuse on a motor, you may want to go with a redline single weight racing oil. You're probably encountering oil temperatures that would just cook most other oils, especially at the bearing in the turbo.

---

The turbo is a hybrid Garrett turbo, with a ball bearing center. Water cooled of course. Like you said, the biggest concern is local hot spots. During a race, the turbo is glow-red hot, so I can imagine the local temperatures in the bearing core are pretty high.

If I were to run a regular racing weight oil, say perhaps a redline SAE 40, how would this effect my limited daily driving. As long as I am willing to let the car get good an warm before getting any RPMS, I would think it would work well. Given that the race gas is 5$ a gallon, the price difference between Mobile 1 and Redline doesn't really factor in too much.

Also, at such high boost levels there is a much greater amount of blow-by, which results in some fuel mixed in with the oil. Any particular oil that is more resistant to that kind of abuse?


Jeff

[ April 18, 2003, 10:50 PM: Message edited by: BOBISTHEOILGUY ]

 

[Drew99GT]

Good god, the sound of that motor is music to my ears! Very nice ride

Your setup and climate is a definate trade-off. If you lived where you were starting the motor cold in ambient emps of like 60 degrees and above, I'd say redline 30 or 40 weight racing oil. But in Oregon, it can get cold, so a multigrade might be a better choice. But 24 pounds out of a high CFM turbo just absolutely punishes an engine and the oil in it.

 

[Drew99GT]

Is your turbo just a straight T04E with like a 60 trim wheel or something? Or does it have some of the Garret GT ballistic goodies inside? Like their bad *** double ball bearing center section? Some of the other companies ball bearing center sections just suck (turbonetics

) Is yours internally gated?

[ April 18, 2003, 02:41 PM: Message edited by: Drew99GT ]

 

[metroplex]

A 5W-50 or 0W-40 full synthetic might be in order.

You want the oil to reach all your parts very quickly, so a 5W or 0W will do the trick, but you need something thick enough to take all that punishment. 40 or 50 weight will do the trick.

 

[Pablo]

I run Amsoil 20W-50 Series 2000 Racing Oil in my turbo year 'round.....

24+PSI? Cool!!!!!!!!!!!!!

 

[Rallyfan]

Nice Scooby. Your apparent lack of an FIA restrictor plate coupled with what I'm guessing is a non-homologated turbo are a breath of fresh air!

You might ask the same question at Scoobynet's UK board; I think they have a wider assortment of road racers and rallyists than NASIOC or I-Club and using my powers of telepathy I predict they'll say check out what GroupN teams run and/or look into M1 15W-50, M1 0W-40, or Motul 300v 5W-40 or xW-50 stuff, full synth. (Since they are UK I don't know their take on Redline, frankly, but I do know of people running it in tarmac race cars and having no issues at all - Mitsu 4G63s with TD05-16G or higher turbos etc.).

With the time and money you've got invested, you might want to ring up these firms directly and tell them your exact setup, then ask them what to run. Since you have oil temp (and I assume pressure) data to discuss with them, you should fair well and get a good idea what they think - just beware the occasional yahoo that might pick up; rep knowledge varies a bit.

 

[WeyounDS9]

You are a texbook case of a 50 weight oil.
If you dont need it I dont know who would.

MOBIL1 15w-50 AMSOIL 20w-50, Redline 20w-50 come to mind, among others.
Even if your car was as hot I'd never run less than a 40 weight in a Turbo anyway.

You might even consider running a fill (and then do a Oil Analysis) with the Castrol 10w-60 That BMW puts into it's M3's (and now M5 's too I thin).
Its not like the locally available Syntec but a german made synthetic performance oil.

Fred...

 

[nicrfe1370]

If I were in your shoes, I wouldn't run anything thinner than a 10W-40, and would probably go with Amsoil or Redline 20W-50 or Mobil 1 15W-50. The Catrol 10W-60 might be good, but such a wide visc. spread worries me in a turbocharged car. Whatever your choice, oil anaysis is almost a necessity, to learn what oil works, and for how long.
I would also call or write Garrett, ask them for their advice. The motor will survive with probably any good oil, but I think the turbo is going to require something beyond that.
I ran Amsoil 20W-50 in my bone stock WRX for a track day at New Hampshire International Speedway with ambient temps. in the 90's, and in the following oil analysis, lead was 93 PPM, where as any analysis before in never rose above 4 PPM. I don't know if this was a deficiency in the oil, or if the force of hard cornering caused some oil starvation. I did another track day at Lime Rock recently, as the ambient temp. was in the 50's, I went with Amsoil 10W-40. I have yet to sample this batch, but when I do I'll post it, see how it compares to the 20W-50. Another thing I did differently was to be sure the sump was filled right to the top, and actually a bit over. I read that BMW owners that race their cars (at least older cars) typically overfill by a quart to prevent oil starvation.

 

[boxcartommie22]

try synergyn's oils the racers use that oil along with redline and mobil 1

 

[satterfi]

Send an email to Redline and ask them. It might take a week for an answer but they will give you their opinion.

 

[TooSlick]

Jeff,

What I would do here is choose a viscosity that gives you 10-15 psi/1000 rpms of engine speed under full out racing conditions on a 90F day. So at 5000 rpms, you want to be in the 50-75 psi range. If the oil you use is too thick, it won't circulate rapidly enough to properly cool the motor and the turbo - particularly the turbo. In addition the oil pressure relief valve probably opens at about 75-90 psi, so pressure higher than this is wasted.

As a rule of thumb, starting w/ an oil temp of @ 90C/194F, for every 10C/18F increase in oil temps, the oil is going to thin out by approx one SAE grade. Your racing temps are 15C-20C higher than your oil temps in street driving, so you'd want to go up 1-2 SAE grades. Assuming a 30wt synthetic is ideal for street use and I think it is, you could go with either a 10w-40 or 15w-50/20w-50 synthetic for warm weather racing.

I'd probably opt for the 10w-40 initially - Amsoil or Redline - and check the oil pressure as I recommended. A common problem for street racers is using too heavy an oil and not getting adequate oil circulation and cooling. With a high rpm engine, oil pressure is rarely a problem. In addition this high rpm operation will increase the oil film thickness in the valvetrain and between the rings and cylinder walls. You are using stock valve springs and a stock cam lobe profile, so the contact loads between the lobes and valve lifters should not be excessively high. The engine oil temps will run higher with a 20w-50 than with a 10w-40, which is self defeating to some degree ....

If you run into any problems, please give me a call and I'll be glad to assist you.

TooSlick
Dixie Synthetics
(256) 882-0768

 

[Steve S]

Too Slick is right on the money. Here is an engine in need of a synthetic . The engine has to put out alot of heat!!!.

[ April 19, 2003, 10:50 AM: Message edited by: Steve S ]

 

[TooSlick]

Patman,

If you don't make engineering decisions based on hard data, you're just guessing. I'd probably go with higher flow over an incremental improvement in filtration efficiency for a high performance application. I can't believe a filter would change things by more than a few psi, so you should still be in the same range with the same SAE grade.

TooSlick

 

[Idrinkmotoroil]

I think a 10w-40 would probably be the best of all choices - although a straight race 40 weight would be a good choice for race days but you would swap it out more often and that can be expensive. To get the kind of power you are making through added boost levels, the increased cylinder pressures are causing the connecting rods to push harder on the crankshaft which will show wear at the bearings more than anywhere else. Thus you definitely need a thicker viscosity to cushion the increased force being exerted at the bearings with each combustion explosion. The 40 weight should still circulate efficiently, slightly better than a 50 weight I guess. I would stick to the premium synthetic oils to prevent coking of the turbo, thus something like Redline, or Mobil1's Delvac come to mind, Amsoil should work good as well. The more anti-wear additives the better IMO.

 

[Patman]

quote:

---

Originally posted by TooSlick:
Patman,

If you don't make engineering decisions based on hard data, you're just guessing. I'd probably go with higher flow over an incremental improvement in filtration efficiency for a high performance application. I can't believe a filter would change things by more than a few psi, so you should still be in the same range with the same SAE grade.

TooSlick

---

I say this because between an AC Delco filter and a K&N oil filter on my Firebird, I see 10psi difference in oil pressure at the redline! Who knows if the gauge is accurately reflecting the difference, but my point is that I couldn't make the proper assessment with your formula because of these differences.

 

[Michael SR]

how are you keeping your on-track oil temps so low? that must be an impressive cooler.

given the sane oil temps, i wouldn't think you'd necessarily need a 50 weight oil. on the other hand, i doubt it makes much difference. in your case, the tune will determine the engine's life, not the oil.

-michael

 

[Patman]

quote:

---

Originally posted by TooSlick:

What I would do here is choose a viscosity that gives you 10-15 psi/1000 rpms of engine speed under full out racing conditions on a 90F day. So at 5000 rpms, you want to be in the 50-75 psi range.

---

The problem with choosing a viscosity with this method is twofold. Number one, how do we know if our oil pressure gauges are truly accurate? And two, changing brands of oil filters could change the oil pressure at WOT, I see the same thing on my Firebird. A better flowing filter on my Firebird shows lower oil pressure at WOT.

 

[Dominic]

Patman - I see the exact same thing on my Camaro, so you're not just seeing things... and my V6 runs considerably higher pressures than the LS1.

You really do need to try about 3 to 5 different oils and have each one analysed to figure out what is right. Everything else is indeed guessing in the wind. I would imagine an awesome 40wt oil would work very well, even considering the horsepower being thrown at that engine and turbo.

I have run M1 15W-50 in a few applications before, and I found it to do exceptionally well in hard running air cooled engines. I would probably end up running the M1 15W-50 and then try to find something *better* as I went along.

I personally don't see why if you're spending $5.00/gal on race fuel and rebuilding the engine every 40,000 miles, you don't just change the oil out every race. I know I would. It costs less than $20 and takes very little time to drain and fill before you hit the track, and you could run a more appropriate track oil for those race days and it would still get you home.

i.e. Your favorite 10W-40 for all around driving and M1 15W-50 or some SAE40 or SAE50 race oil on those *hard* running days.