Oil suggestions for supercharged Subaru BRZ

[Cjsporl]

Originally Posted By: 05LGTLtd
Have to keep in mind the internals. A subie that comes with a turbo from the factory is not a High compression engine. A car that starts out as NA DI engine with a high compression rating that gets a bolt on SC kit is something entirely different.

The OP stated "20:1 compression" not sure what he means by that.



Boost and Altitude Correction to Compression

You are running 11 PSI of boost at an altitude of 112 feet. Your motor's static compression is 12 :1. At this boost level and altitude your effective compression ratio is 20.96 :1, and without altitude correction your compression ratio would be 20.98 :1.

this is what my compression ratio is 20.98 :1

 

[Cjsporl]

information regarding your question is above.

 

[Cjsporl]

Originally Posted By: CentAmDL650
With 20:1 compression ratio

I would be much more concerned about what fuel to run to prevent detonation.

If it were me running an aftermarket forced induction system, for dependability I would have spent the bucks lowering the static compression ratio with dished pistons and/or bigger cc combustion chambers. I would want to know what my oil pressure and temperature looked like on a data recorder, would want a tuneable ecu to control a higher flowing fuel pump and injectors, and would think about a Gr. IV or V oil that had a rep for both low oxidation at high temps and low or no- shearing.

That said, why not get a UOA on what you have in the sump already to get a baseline for future adjustment?


My car was tuned by a very reputable tuner in my area. He didn't find a reason to build the block as we have not seen any knock on 93 octane. Stock injectors and fuel pump are not maxed out either. My car uses a unique system using both port and direct injection. I don't have any oil temp gauge in my car.

 

[Oil Changer]

You need more gauges. Mine would include fuel pressure, boost, oil pressure and oil temp. That is if you want to do it right. Until then, I still say M1 0W-40 and possibly 5W-50.

 

[Zaedock]

Mobil 1 0W40 is a solid choice. It's the best deal going as 0W40 is one of Mobil's best and only $22-$25 a jug at Walmart.

 

[Shannow]

Originally Posted By: Cjsporl
Boost and Altitude Correction to Compression

You are running 11 PSI of boost at an altitude of 112 feet. Your motor's static compression is 12 :1. At this boost level and altitude your effective compression ratio is 20.96 :1, and without altitude correction your compression ratio would be 20.98 :1.

this is what my compression ratio is 20.98 :1


'cept it doesn't really work like that...

 

[john_pifer]

Yep, that's more than most diesels.

 

[Zaedock]

Originally Posted By: Shannow
Originally Posted By: Cjsporl
Boost and Altitude Correction to Compression

You are running 11 PSI of boost at an altitude of 112 feet. Your motor's static compression is 12 :1. At this boost level and altitude your effective compression ratio is 20.96 :1, and without altitude correction your compression ratio would be 20.98 :1.

this is what my compression ratio is 20.98 :1


'cept it doesn't really work like that...

12:1 with 11 PSI of boost is roughly 15.87 ECR.

 

[05LGTLtd]

Originally Posted By: geeman789
Originally Posted By: bluesubie
There are some good uoa's on Red Line 0W-20 over on ft86club.com from a supercharged, tracked 86. I'd go with RL xW-20, Motul 300V 0W-20, Amsoil HDD 5W-30, Amsoil Dominator 5W-20, or a Euro xW-30 like Euro Castrol or Motul X-lite.

Pretty much any oil with an HTHS of 3.5 or higher OR a race oil. I presume you have an oil pressure gauge. You can also experiment with mixing to fine tune your choice if you feel like playing backyard oil blender.

-Dennis


Not recommending M1 5w30 ESP anymore....?


If you Don't feel comfortable with M1 0w-40, or blending it down to a thick 30wt, the 5w-30 ESP would seem to be a good choice since the OP is comfortable with Mobil products.

http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_ESP_Formula_5W-30.aspx

Is this a four season car? How long have you run previous OCI's? How long of an OCI do you plan on running?

 

[bluesubie]

Originally Posted By: geeman789
Originally Posted By: bluesubie
There are some good uoa's on Red Line 0W-20 over on ft86club.com from a supercharged, tracked 86. I'd go with RL xW-20, Motul 300V 0W-20, Amsoil HDD 5W-30, Amsoil Dominator 5W-20, or a Euro xW-30 like Euro Castrol or Motul X-lite.

Pretty much any oil with an HTHS of 3.5 or higher OR a race oil. I presume you have an oil pressure gauge. You can also experiment with mixing to fine tune your choice if you feel like playing backyard oil blender.

-Dennis


Not recommending M1 5w30 ESP anymore....?

That was covered with the Euro xW-30 and HTHS comment.

Euro as in Euro specs, not necessarily an oil from Europe.

-Dennis

 

[capn233]

This is an otherwise stock motor that has a supercharger kit and a tune? How much higher are the oil temperatures now?

The Redline 0W-20 idea sounds pretty good to me. Also think the suggestion for some new gauges is a good one.

 

[Cjsporl]

Yes, this is a 4 season car. My oil change intervals are between 5-6 thousand. This is a stock motor with nothing but a supercharger, headers, and a header back exhaust system. I should also note that the new 2015 wrx uses the same engine but with a turbo so the bearing clearences are exactly the same. That wrx calls for 5w30. What makes everyone think a 40 weight is safe. Especially since I do not have any way to properly read what my engine is doing. I plan on running the new penzoil platinum for my next oil change.

 

[artificialist]

Originally Posted By: Cjsporl
Yes, this is a 4 season car. My oil change intervals are between 5-6 thousand. This is a stock motor with nothing but a supercharger, headers, and a header back exhaust system. I should also note that the new 2015 wrx uses the same engine but with a turbo so the bearing clearences are exactly the same. That wrx calls for 5w30. What makes everyone think a 40 weight is safe. Especially since I do not have any way to properly read what my engine is doing. I plan on running the new penzoil platinum for my next oil change.

Sure, Subaru turbo engines allow 5w30, but in the UOA section, it appears that M1 0w40 and Shell RT6 5w40 give better results than 5w30.

This is why my car allows 5w30, but I use 0w40 anyway. However, I use Castrol 0w40. The European version of my car recommends 0w40, does the European variant of your car call for something heavier than 0w20?

Does your engine use an oil cooler? I don't know if the Subaru WRX has one, but if it does, it allows a lighter viscosity.

Another thing that determines engine heat is intake air temperature. The WRX is intercooled, is your supercharger equipped with an intercooler?

 

[CATERHAM]

Originally Posted By: bluesubie
Originally Posted By: geeman789
Originally Posted By: bluesubie
There are some good uoa's on Red Line 0W-20 over on ft86club.com from a supercharged, tracked 86. I'd go with RL xW-20, Motul 300V 0W-20, Amsoil HDD 5W-30, Amsoil Dominator 5W-20, or a Euro xW-30 like Euro Castrol or Motul X-lite.

Pretty much any oil with an HTHS of 3.5 or higher OR a race oil. I presume you have an oil pressure gauge. You can also experiment with mixing to fine tune your choice if you feel like playing backyard oil blender.

-Dennis


Not recommending M1 5w30 ESP anymore....?

That was covered with the Euro xW-30 and HTHS comment.

Euro as in Euro specs, not necessarily an oil from Europe.

-Dennis

Suggesting only to run an oil with a 3.5+cP HTHSV is the same as saying only run 40 grade (or near 40 grade) oils which the OP doesn't likely need to do.

The first thing the OP should do is install a set of oil temp' and oil pressure gauges. I presume he has installed an oil cooler as the BRZ does generate high oil temp's when tracked.
If the use of the car is just for fast road work, oil temp's may not get that high and the spec' 0W-20 should work ideally.

 

[Zaedock]

Originally Posted By: Cjsporl
Yes, this is a 4 season car. My oil change intervals are between 5-6 thousand. This is a stock motor with nothing but a supercharger, headers, and a header back exhaust system. I should also note that the new 2015 wrx uses the same engine but with a turbo so the bearing clearences are exactly the same. That wrx calls for 5w30. What makes everyone think a 40 weight is safe. Especially since I do not have any way to properly read what my engine is doing. I plan on running the new penzoil platinum for my next oil change.


The oil weight in your app has nothing to do with bearing clearances (which haven't changed much since ICE's have been around). It has to do with oil temp. If a 40wt could cause bearing damage then everyone's engine would blow up in the winter time.

If you're spending the coin to add a supercharger, then oil pressure and temp gauges are a no brainer. A 30wt may be ideal for you, heck a 20wt may be ideal, but you simply don't have enough info to know. Folks who supercharge without oil info are safer (IMO) running a 40wt, such as the aforementioned Mobil 0W40.

 

[geeman789]

Originally Posted By: Zaedock
Originally Posted By: Cjsporl
Yes, this is a 4 season car. My oil change intervals are between 5-6 thousand. This is a stock motor with nothing but a supercharger, headers, and a header back exhaust system. I should also note that the new 2015 wrx uses the same engine but with a turbo so the bearing clearences are exactly the same. That wrx calls for 5w30. What makes everyone think a 40 weight is safe. Especially since I do not have any way to properly read what my engine is doing. I plan on running the new penzoil platinum for my next oil change.


The oil weight in your app has nothing to do with bearing clearances (which haven't changed much since ICE's have been around). It has to do with oil temp. If a 40wt could cause bearing damage then everyone's engine would blow up in the winter ...


So many think that an engine spec'ing a 20 grade will just BLOW up if you use a 30, 40 or 50...!

IT WON'T... REALLY...!

People seem to forget that the 20 grade at 40 *c is waaaaaay thicker than the 40 grade is at 100*c, as in 5x thicker, give or take... and at lower temps ALL oil grades are many many times thicker than at operating temps. As oil warms up, it gets THINNER, as it cools, it gets THICKER...!

A 20 grade at 100*c is about the same thickness as a 30 grade at 110*c, and a 40 grade at 120*c, again, approximately.

Every time you start your car cold, for the next 15 minutes or so, EVERYONE is using too thick oil...!

Using a 40 grade oil in this app. may or may not be required... but it certainly won't hurt anything. But without some oil temp data, everything is speculation at this point.

 

[john_pifer]

OK, everybody can quit posting till the OP get some gauges.

 

[Shannow]

Guages will tell you what the operational viscosity of the oil is, but tell you absolutely nothing about where that viscosity leaves you on (say) the Stribeck Curve with the increased cylinder and bearing pressures that the supercharged engine is producing...particularly if there's some detonation going on from the stock C.R. and the boost before the revs are really up.

In that case, a 30 will always provide a greater margin of safety than the stock 20 (which MAY be usfficient, but oil pressure/temperature don't tell you that)

 

[Shannow]

Originally Posted By: CATERHAM

Suggesting only to run an oil with a 3.5+cP HTHSV is the same as saying only run 40 grade (or near 40 grade) oils which the OP doesn't likely need to do.


Actually, and for correctness, 3.5 is the "natural" HTHS for a 30...a non VIIed 30 grade, which is the definition of a 30 grade has an HTHS of around 3.5.

The "minimum" HTHS specifications (well actually the HTHS specs themselves) only came into existance after multigrades were marketted, and some with excessive temporary shear properties caused problems.

 

[Cjsporl]

Originally Posted By: john_pifer
OK, everybody can quit posting till the OP get some gauges.


well, I can get some of that info through the OBD2 Port. What should I be monitoring to figure out the best oil weight?

here is the dyno sheet