Any benefit of switching to 5W-30 from 5W-40??

[SuperEd73]

Hello BITOGers,

Ok, here's my question. Right now I'm running RTS 5W-40 in my Subie WRX. I'm just about due for an oil change. I live on Long Island which has temperatures during the winter mainly at or just below freezing with occasional cold snaps such as one expected later this week with lows in the single digits. I have some SynPower 5W-30 sitting around that I could use. I know in theory the 5W is the "winter" or cold rating but I'm curious if I can/should continue to use 5W-40 or switch to a 5W-30 for the winter?

Thoughts?

Ed B.

 

[Norm Olt]

5W-30 is usually available at a much lower price...

 

[Smokescreen]

What about 0w40?

 

[demarpaint]

Hi Ed,

Fellow L.I.'er here. The 5W30 oil will flow easier than the 5W40 during the cold winter months. With all that said what does Subaru call for for your WRX? Using their recommendation is always a good idea.

I just had look at the newspaper and they're calling for 3*F Thursday morning.

Frank D

 

[addyguy]

Personally, in a high-strung turbo engine, I wouldn't run less than a high 30-weight, like GC 0W-30. I'd second the rec. for 0W-40, and use M1 0W-40, which shears to a high 30-weight anyway...

 

[Steve S]

What does the mfg recommend?

 

[SuperEd73]

Steve S,

Based on the owners manual they recommend 5W-30 for fuel economy purposes. There is also a little graph that shows the temperature range for various oils. 5W-30 shows the best all around range. There is a 2nd bar that lists 10W-40, 10W-50, 20W-50 can be used in temps down to 0F.

The Subie turbo engines do tend to beat up on the oil. Various UOAs show xW-30 oils get sheared down to something more like an xW-20 pretty quickly. So, that's why I was running 5W-40. Now that it's colder here I'm just curious if 5W-40 might be too heavy for this time of year or not.

If it helps, my daily commute to work is only about 15 minutes and 6.5 miles.

Ed B.

 

[demarpaint]

Based on that I would lean toward PP 5W30, but since you already have the Synpower, then use it up. 6.5 miles and a 15 minute commute the oil is probably not even hitting operating temperature, and would be another reason I would lean toward the 5W30.

JMO

 

[Audi Junkie]

Put some in the freezer, even 10w-30 synth is much thinner at 0f than 5w-40. I'd use the RTS in summer and PP in winter. Seasonal changes are best 2-3-4 times a year.

 

[PT1]

Originally Posted By: demarpaint
Based on that I would lean toward PP 5W30, but since you already have the Synpower, then use it up. 6.5 miles and a 15 minute commute the oil is probably not even hitting operating temperature, and would be another reason I would lean toward the 5W30.

JMO



+1 Me too. I use PP 5w30 and it cranks fine at 0*F

 

[OVERKILL]

Originally Posted By: Audi Junkie
Put some in the freezer, even 10w-30 synth is much thinner at 0f than 5w-40. I'd use the RTS in summer and PP in winter. Seasonal changes are best 2-3-4 times a year.


If I had some 10w30, I could test that right now. It's -20C here right now.....