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2010 XT Forester
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48 Posts
Discussion Starter · #1 ·
I bought this XT a year ago. The engine was rebuilt and right now has 26,000km's, I use PP 5W30 in my 2010 XT. Last winter I used this and it would start, but crank slowly when the temperature was -10c and well below that. At -20c and below it would even take a 2nd turning of the key to get it to start!!

At these extremes of cold can I use 0W30 instead of the 5W30 to possibly help with the cold temps cranking? The manual does not say to use 0W weight oil, so just curious if anyone else has used 0W in their '10 XT Turbo!
 

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2005 Forester Automatic
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495 Posts
Yes, but use the best 0W30 you can find, should be at least synthetic, full being better. PP is not full synth IIRC, but has good reputation.

0w30 and 5w30 both should behave relatively similar once engine is warmed up, as the 30 is the 100C rating. Note that especially in the summer, the engine oil may be quite a lot over 100c, and then the different additive packs might start to make some viscosity difference. So i'd probably say you should switch back to 5w30 before July arrives.....

The 0w and 5w (w = winter ) describe cold weather and startup performance. So the additives in the 0w oil are somehow keeping it "thinner" when cold. The 0 says that this oil behaves in cold (forgive me, I have forgotten the bottom testing number) like a classic 0 weight oil. Except a straight zero weight oil would be like kerosene at 100c. 5 says that the 5w30 oil has the viscosity of 5 weight oil when cold.

So, yes, the 0w30 should be fine, and probably a good idea. You can hurt an engine with stiff oil at startup too. Would not leave it in there through the summer though, just out of superstition mostly I think.

Finally, IMHO, the number you should NOT mess with is the second "warm" number. If you reduce that one, you risk having an oil film that cannot keep the metal surfaces apart (too thin). If you go with a higher, heavier weight oil, you risk not having enough pump to move the oil, or too little flow through the various oil passages that were engineered for a given viscosity of warm oil. Too thick, too little flow = bad juju for engine.....
 

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2018 Forester XT
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1,605 Posts
Gets to -30 - 35 here and I prefer 5w ... always serves me well.

Especially for variance in temp.
 

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2005 FXT
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174 Posts
0W oils generally are superior to 5W regarding pour point at extremely cold ambient temperatures and warm up to operating temperature sooner. The majority of lubricated component damage from wear resistance (or lack thereof) is at startup until operating temperature is reached.
 

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2010 XT Forester
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48 Posts
Discussion Starter · #6 ·
Thank you all for your input here.

The XT is due an oil change this next week or so and 0W30 will be used then. I'm really wanting to see if the 0W weight oil will improve its minus temps cold cranking and starting unless there's some other issue going on. When April rolls around I'll be back to 5W30/40.
 

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2005 FXT
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174 Posts
I mentioned this in another thread recently about oil, but the primary goal should be wear protection/resistance.

This blog has good information, although the monolithic structure/format is awful and you’ll need to search it if you don’t want to spend hours reading it.

https://540ratblog.wordpress.com

Castrol oils haven’t tested particularly well (there is an exception or two) and have gone down in wear protection over time.

I never felt the need to join the blog, but I want to send some oils for testing, so I’m joining. It’s free to join and have his testing done, just pay for a quart and the shipping.
 

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2004 FXT / 2020 Outback Onyx XT
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1,678 Posts
I mentioned this in another thread recently about oil, but the primary goal should be wear protection/resistance.

This blog has good information, although the monolithic structure/format is awful and you’ll need to search it if you don’t want to spend hours reading it.

https://540ratblog.wordpress.com

Castrol oils haven’t tested particularly well (there is an exception or two) and have gone down in wear protection over time.

I never felt the need to join the blog, but I want to send some oils for testing, so I’m joining. It’s free to join and have his testing done, just pay for a quart and the shipping.


His “tests” are meaningless in regards to how an oil will perform inside of an engine.
 

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Premium Member
2019 Crosstrek 2018 XT
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14,644 Posts
His “tests” are meaningless in regards to how an oil will perform inside of an engine.
Exactly..I have done many many used oil analysis and looked at thousands more on BITOG.com. In general WalmartSyn performs as well any other syn. I started using Mobil1 in around 1980 and mostly used syns since then bc I do extended drain intervals.

My honest opinion after many many years is this :" Oil is Oil" all protect about the same.
 

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2 Posts
I haven’t paid attention in recent years since I sold my STis, but found 0w30 German Castrol to be a great oil for the subie boxers. Very good oil, holds up to the punishment that the STi could throw at it and did regular used oil analyses.

It was getting tougher to find, but I believe they carried it at autozone. Check Bob is the Oil Guy for details. I’m sure they are still talking about it if it’s around.
 

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1999 forester automatic
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6 Posts
I would and have used all year round in Colorado Mobil 1 5-30 with great results. There's also a Fram Synthetic oil filter
that cost a couple bucks more than a standard basic oil filter, I go with that.
 
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