Oil recommendations for Subaru 2.4T

[edyvw]

Not only did your reply not address my point, your answer is impossible because the “problem” you propose is self-correcting even though oil doesn’t create a restriction in a positive-displacement pump system.

Your take: heavier oil creates restriction => heat

Heat => causes problems

But you missed the part where: heat => thinner oil

Which is exactly what you didn’t address. A cold 20 grade is magnitudes thicker than a 30 grade at operating temps.

Yep. 5W30 ILSAC will just marginally raise heat. The same goes with Euro oils. If that is a concern, one can lower % of coolant concentrate. But really, it should not be whatsoever.

 

[CarbonToast]

Not only did your reply not address my point, your answer is impossible because the “problem” you propose is self-correcting even though oil doesn’t create a restriction in a positive-displacement pump system.

Your take: heavier oil creates restriction => heat

Heat => causes problems

But you missed the part where: heat => thinner oil

Which is exactly what you didn’t address. A cold 20 grade is magnitudes thicker than a 30 grade at operating temps.

I agree, comparing cold to hot it would look that same. But the engine spends a small % of its time running cold. I'm thinking about under operating conditions, what is different?

Comparing hot to hot the 30wt will be thicker.

If oil weight doesn't cause/change the restriction, then why does oil pressure increase when a heavier weight oil is used?

I agree it seems odd, but maybe they have this thing so optimized for 20wt you could cause a problem going heavier.

 

[kschachn]

I agree it seems odd, but maybe they have this thing so optimized for 20wt you could cause a problem going heavier.

No, there aren't optimizations that would cause a problem. You can "optimize" an engine to tolerate a lower grade however.

Your comment would be descriptive of an exceedingly poor engine design which would fail in short order.

 

[Petr]

Now we don’t know as a fact that 30 oil was used but it was a weird occurrence that on the oil change stickers all of them were from different independent shops and it said xxW30 was used. Well we never seen this problem on a car that came in with history of 20 oil in it. We believe the 30 causes too much resistance for these turbos

Base oil quality difference? Here, quite many independent service garages use cheap oils, and even some official Toyota garages use oils that I really do not like to see in the cars I take care of.

"Pedal to the metal" with cold engine? The difference in oil flow at high RPM between cold 0w20 and cold xw-30 might be significant.

 

[kschachn]

Base oil quality difference? Here, quite many independent service garages use cheap oils, and even some official Toyota garages use oils that I really do not like to see in the cars I take care of.

A good article to keep in mind:

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Does a full moon really trigger strange behavior?

www.scientificamerican.com

 

[CarbonToast]

No, there aren't optimizations that would cause a problem. You can "optimize" an engine to tolerate a lower grade however.

Your comment would be descriptive of an exceedingly poor engine design which would fail in short order.

What I mean is. If they designed the oiling system around a 20wt oil, then they probably made some decisions that optimize its oiling performance with a 20wt oil.

Those design choices might not work with a 30wt.

 

[kschachn]

What I mean is. If they designed the oiling system around a 20wt oil, then they probably made some decisions that optimize its oiling performance with a 20wt oil.

Those design choices might not work with a 30wt.

They didn't. Again, an engine may contain design changes that allow operation on a thinner oil without excessive wear, but those changes do not preclude the use of a thicker oil. As I noted, if that were the case then it would be a terrible design and the engines would all quickly fail.

 

[Petr]

illusory correlation”—the perception of an association that does not in fact exist.

You may be right. On the other hand, few year ago I have seen "fully synthetic oil" that, according to the MSDS, was mostly Group II with some Group III. Standard European OCIs/12 months or 15000 km to 30 000 km combined with severe use help to "separate the wheat from the chaff".

 

[edyvw]

What I mean is. If they designed the oiling system around a 20wt oil, then they probably made some decisions that optimize its oiling performance with a 20wt oil.

Those design choices might not work with a 30wt.

Have you seen how soccer moms drive Ascent with 2.4T? When they step on it, the oil is 200 grade, not 20 grade.
There is no warming up, etc.

 

[nthach]

Just to clarify that the 2.4DIT does not allow/recommend 5W-40. That was only in the 2.0 DIT. They do still allow the Euro 0W-30 though. This is from the JDM WRX manual with the 2.4 DIT.

View attachment 180473

Yea, that was the rationale for me using M1 ESP 0W-30, while the 5W-30 ESP version does carry a dexos2 certification, the 0W-30 grade is a bit more inline with a ILSAC 5W-30.

 

[Al]

I use 0W-40 Mobil 1 on my 2.0 FA Forester engine. I would at least go 30 wt.

 

[Fishstyx]

Proud owner of a 2020 outback live in Idaho hot summers and freaking freezing cold winters I have always ran 0W20. Since I bought it. I use Toyota 0W20 since the wear and friction reduction add pack is really impressive. I have never had a problem with 0W20 and I just switched back to the black Tokyo Roki filter for Subaru. Excellent filter.

 

[kschachn]

Proud owner of a 2020 outback live in Idaho hot summers and freaking freezing cold winters I have always ran 0W20. Since I bought it. I use Toyota 0W20 since the wear and friction reduction add pack is really impressive. I have never had a problem with 0W20 and I just switched back to the black Tokyo Roki filter for Subaru. Excellent filter.

Really? How is it better than other add packs? Who makes the add pack for Toyota oil?

 

[Fishstyx]

Really? How is it better than other add packs? Who makes the add pack for Toyota oil?

Exxon makes it. the Molybdenum is equal to the ZDDP in it in the ppm. Not even mobile 1 has that add amazing package. I been running it since the first oil change.

 

[kschachn]

Exxon makes it. the Molybdenum is equal to the ZDDP in it in the ppm. Not even mobile 1 has that add amazing package. I been running it since the first oil change.

But you said wear and friction reduction. I don’t care about elements from a spectographic analysis or typical properties PDS, how are you measuring wear and friction reduction?

Also what is the molybdenum compound that’s equivalent to ZDDP “in the PPM”?

 

[Fishstyx]

As you know Molybdenum is a friction reducing agent. It doesn’t prevent wear. ZDDP is a wear preventative additive that doesn’t decrease friction when they are equal in ppm it becomes a synergistic response and each work together to increase wear protection and decrease friction. Basic chemistry.

 

[kschachn]

All right, so you don’t really know.

 

[Fishstyx]

All right, so you don’t really know.

I understand that you have doubts. But start at 13:30 on this video and you will understand the importance.

 

[goingplacesanddoingstuff]

HPL, Amsoil, or Mobil1 ESP 0w30 would be my choices.

 

[kschachn]

I understand that you have doubts. But start at 13:30 on this video and you will understand the importance.

No, I don’t have doubts. But thank you anyway.