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Hands Down What Should We Be Using For An Oil All Year Round On The Sti's? Im Currently Using Royal Purple 5w-30 And Oem Filter. Good? Bad? I Live In New England....
 

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ok........so i read all 8 chapters and even did the quizz's. I am still confused. Where does the "30" in 10W-30 come from? The W comes from the cold temp cS right? I get that the lower the "W" the better, because it has a lower V at startup, but it still maintains about the same V as a heavier weight oil at high temps. Also what the hell is as "straight" oil like "straight" 30? So in the end what oil should we be using for our cars in

1. DD street only
2. Heavy street/light track
3. Track only
 

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Great write up, for the people that actually spend the time to read through the whole thing, it will provide them the information they need to make an educated decision on what oil they should be running. I think this weekend I am going to change my DD civic oil to 0-30, I think that i am going to leave the STI at 5-30 for now but in both of them they are going to stay Synthetic for obvious reasons in the article.

This was great to send to my buddy who has a 70 challenger who thinks that he need to put in 10-40 or thicker plus a **** load of oil stabilizer, then wonders why the car is running hot...
 

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Excellent but heres a question.

"previously" before i read this i was lead to believe that the cooler the oil the better and i have fitted a greddy oil cooler on top where the Top mounted standard intercooler was (now have FMIC)

I dont track the car and im pushing 400+ WHP which gets used fully once or twice a day

Is this a good idea to use a oil cooler for daily use.?

"have i missed the point.?" it is 1am and a few beers later.!
 

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Also ,

im 3,000km into a new built cosworth block and running mineral "from Subaru" and have changed twice now.once at 1,600km as recommended by Cosworth and again at 2,400km because i wanted to. Ive read in other parts of IWSTI that you should only change to synthetic after around 15,000km but after reading this thread im not so sure and i think it would be better to change right now to fully synthetic.

Any comments.?
 

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Does your oil cooler adapter have a thermostat to regulate temps? If so it is fine to run all the time.

Switch to synthetic whenever you want. I went 1,500 miles on dino then switch to synthetic after breaking in an engine.
 

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I read all the chapters but I'm not sure how to determine if my 2005 STI in Arizona is @ 10PSI per 1000rpm. All I know is my tuner recommended Shell Rotella 15w 40 due to the hot weather here. But according to this write up, 15w anything is bad due to how thick it is at startup vs other thinner oils. On top of that, Rotella is not synthetic. The previous owner of my car used Amsoil 10w40 in Florida, but Amsoil 0w40 seems to be a better choice. Man my head hurts now... I hear Subarus love Rotella, but i'm not sure where that all started. I know alot of people run it and have very little oil consumption (something that wasn't really covered in this write up). Regardless, I think I'm going back to Amsoil synthetic on my next oil change. I'll even give the 0w30 a shot in this 115 degree summer Arizona heat. I agree with the logic that oil at startup should be as light as possible but still optimum at roughly 212 degrees F. Interesting write up for sure. Now to test some oils.
 

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I read all the chapters but I'm not sure how to determine if my 2005 STI in Arizona is @ 10PSI per 1000rpm. All I know is my tuner recommended Shell Rotella 15w 40 due to the hot weather here. But according to this write up, 15w anything is bad due to how thick it is at startup vs other thinner oils. On top of that, Rotella is not synthetic. The previous owner of my car used Amsoil 10w40 in Florida, but Amsoil 0w40 seems to be a better choice. Man my head hurts now... I hear Subarus love Rotella, but i'm not sure where that all started. I know alot of people run it and have very little oil consumption (something that wasn't really covered in this write up). Regardless, I think I'm going back to Amsoil synthetic on my next oil change. I'll even give the 0w30 a shot in this 115 degree summer Arizona heat. I agree with the logic that oil at startup should be as light as possible but still optimum at roughly 212 degrees F. Interesting write up for sure. Now to test some oils.
Unfortunately, that article has some issues so I would not even think too much about that information. Read the comments here with input from engineers and a tribologist. Dr Haas' Motor Oil University Article.

A 15W must pass the cold weather cranking test at -20C and a 10W must pass it at -25C.
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I would say the main problem with Rotella 15W40 is that it's not a "synthetic" oil, although it's probably an ok choice if you plan to change your oil every 2,500 -3,000 miles max. Amsoil 10W-40 would be a better choice as it is a very stable oil (less viscosity modifiers than a 0W). Not sure which Amsoil 10W40 you are referring to, but Amsoil XL 10W40 is very slightly thicker than Amsoil AMO 10W40 at operating temp. The XL 10W40 is closer in viscosity when hot to the Rotella 15W40 than the AMO is, although AMO is made from better base stocks and I believe it has more ZDDP.

The only 30 grade Amsoil that I would run in that car is Amsoil HDD 5W30. And that's only if I confirmed that the oil pressure was good during the entire interval. HDD makes Rotella T6 5W40 look light (in additives, but not viscosity). Again, don't stress about the cold cranking viscosity unless you plan on driving your car to Saskatchewan. ;)

Rotella T6 5W40 gained popularity among many enthusiasts over the past few years because it is a mixed fleet gas/diesel oil that meets API SM specs for gas engines, has a decent amount of ZDDP, and is easy to find. Another good 40 grade oil that I would consider in AZ that's easier to find than Amsoil is Mobil1 10W40 High Mileage.

-Dennis
 

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Again, don't stress about the cold cranking viscosity unless you plan on driving your car to Saskatchewan. ;)

Rotella T6 5W40 gained popularity among many enthusiasts over the past few years because it is a mixed fleet gas/diesel oil that meets API SM specs for gas engines, has a decent amount of ZDDP, and is easy to find.
I live in Saguenay which means COLD winters, moderate summers and limited choices for oil.

I've been running German Castrol 0w30 because it's easy to find. My STi devours it but doesn't seem to smoke and passes leak down test (10-15%..) Some oil in TMIC

Now they are replacing German Castrol 0w30 with 0w40 here.. Same label, Euro formula, but now made in Belgium. Apparently 0w30 was a "heavy 30" and 0w40 is a "light 40"

It comes in 5L now and was 40% off so I grabbed a few.. I only ever found 0w30 in 1L :cool:
 
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