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OK, my '03 Legacy GT has had a steady diet of 5W-30 conventional.  However during the teens and - degrees days we are having in Northern New England was wondering is a lighter wait would allowfor faster cranking and better flow.

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The cold snap wont be lasting much longer - get a magnetic oil pan heater - they work great in situations like this.

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The only better option would be a synthetic 0w-30 or 0w-40 oil, which tend to be very expensive.

A 5w-30 synthetic will flow better than conventional 5w-30 in the cold, and still provide the proper viscosity at operating temp, without breakign the bank.

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The only better option would be a synthetic 0w-30 or 0w-40 oil, which tend to be very expensive.

A 5w-30 synthetic will flow better than conventional 5w-30 in the cold, and still provide the proper viscosity at operating temp, without breakign the bank.

 

Synthetic oil does not flow any better,

Viscosity is viscosity,

If they flowed different,viscosity  #s would be different.

 

I would not use 0w-30 unless the owners manual says it is OK,

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magnetic pan heater sounds interesting for a simple temporary solution.

 

it is said 0w is too light for older Subaru engines so i avoid it but i have no experience running 0w, i don't think the owners manual recommends it does it? 


Mine seemed to be starting fine and we were seeing down to -8 earlier this week.

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Synthetic oil does not flow any better,

Viscosity is viscosity,

If they flowed different,viscosity  #s would be different.

 

I would not use 0w-30 unless the owners manual says it is OK,

 

I thought the same as you... all 5W-30s would be equally viscous. That must true under the temperatures and conditions of the viscosity rating test, but it seems to be untrue in practice- synthetic oils just seem to be less viscous when judged by how they pour. (Note, I'm not a synthetic oil fanboy by any means, I use Dino oil and only use synthetics when the manufacturer mandates it.)  I'd be interested to hear if anyone else has observed this and if they understand the reason.

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First I have ever heard of synthetics not having a lower powering point per viscosity. I remember years ago seeing an oil chart that list dozens of manufactures and synthetic lines would be 10-20 degrees lower power points than conventional within same brands. 

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Synthetic oils do not thicken as much as conventional oils when they are cold.

Synthetics often have better cold cranking viscosity ratings, which means they are more easily pumped through the engine, even if they appear to visibly flow the same as a conventional oil.

 

Bobistheoilguy.com is a great resource for learning about the various tests that motor oils are put through.

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The cold snap wont be lasting much longer - get a magnetic oil pan heater - they work great in situations like this.

Well here in Northern New England we always have few - degree days sprinkled in each winter.

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Well here in Northern New England we always have few - degree days sprinkled in each winter.

 

Try living in northern Wisconsin - minus zero temps are the norm for weeks at a time - maybe not -25 to -30 on a regualr basis, but minus single digits & teens are commonplace from around Christmas to sometime in February. Usually have about a week, maybe two of consistant -15 to -20 temps in January

 

I dont use the oil pan heater on a regular basis - but when temps are going to be minus 20s or lower - yeah, not a bad idea.

 

during the recent "Polar Vortex" cold snap, we saw actual temperatures around -30 to -35... wind chills in the -50 range. Lots of folks had cars that wouldnt start for a couple of days...

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Even running Semi-Syn 10W-30 in my EJ22 it cranks slow in the early morning when it's around 0*F and it'll have lifter tick for a couple mins, I just let it idle and it warms up and sounds normal.  I wouldn't stress it too much, just don't hop right in the car and drive off, even after a few minute warm up you should take it easy until the engine is up to full operating temp.  You could add a couple OZs of Marvel Mystery Oil and it might help out some.

 

My biggest problem is the brake booster doesn't work when it's 0* and below until the temp warms up under the hood after 5-10mins.

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Synthetic oil does not flow any better,

Viscosity is viscosity,

If they flowed different,viscosity  #s would be different.

 

I would not use 0w-30 unless the owners manual says it is OK,

 

 

First I have ever heard of synthetics not having a lower powering point per viscosity. I remember years ago seeing an oil chart that list dozens of manufactures and synthetic lines would be 10-20 degrees lower power points than conventional within same brands. 

 

 

Synthetic oils do not thicken as much as conventional oils when they are cold.

Synthetics often have better cold cranking viscosity ratings, which means they are more easily pumped through the engine, even if they appear to visibly flow the same as a conventional oil.

 

Bobistheoilguy.com is a great resource for learning about the various tests that motor oils are put through.

 

Let me rephrase that,boys.

 

Since all 5W-XX oils are viscosity tested at a temperature well below those mentioned by the OP, there would be no flow advantage to synthetic.

Edited by naru

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The viscosity modifiers in today's non-synthetic oils are pretty good.  It used to be the case that synthetic had a much better viscosity index, but now not so much.

 

The "winter" grade rating (the 5W in 5W-30) is measured at 0 deg F.  The viscosity index is similar for a synthetic 5W-30 as is a dino 5W-30, which would make sense as they have the same viscosity ratings.

 

Where synthetic really shines is in wear protection (dry starts, high heat) and also resistance to overheating and coking.  Synthetic also has better stability so over time the viscosity will remain consistent; this is why oil change intervals can be longer with synthetic.

 

I use Shell Rotella T6 synthetic 5W-40.

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The viscosity modifiers in today's non-synthetic oils are pretty good.  It used to be the case that synthetic had a much better viscosity index, but now not so much.

 

The "winter" grade rating (the 5W in 5W-30) is measured at 0 deg F.  The viscosity index is similar for a synthetic 5W-30 as is a dino 5W-30, which would make sense as they have the same viscosity ratings.

 

Where synthetic really shines is in wear protection (dry starts, high heat) and also resistance to overheating and coking.  Synthetic also has better stability so over time the viscosity will remain consistent; this is why oil change intervals can be longer with synthetic.

 

I use Shell Rotella T6 synthetic 5W-40.

 

Actually,5W oils are measured at -25 C(-13 F).

 

I am not anti synthetic.

I use it in a turbo car for its superior high temperature performance.

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Actually,5W oils are measured at -25 C(-13 F).

 

I am not anti synthetic.

I use it in a turbo car for its superior high temperature performance.

 

Actually, we're both wrong.  Oh, the arrogance!

 

They used to measure the viscosity at 0 F, but now in SAE J300 they don't really measure viscosity.  Each weight class (0W, 5W, 30, 40, etc) has a defined set of parameters that the oil must meet.  In the Nov 2007 version of SAE J300, with 5W the cranking test is at -30C and the pumping test is at -35C.

 

Anyway I think the temperature these contrived tests are run at is not really relevant to this conversation.  With a synthetic versus a non-synthetic of the same viscosity rating, it won't make a difference in cold starting.  However there are some synthetics that offer a greater viscosity range. For example while there are some synthetic 0W-50 oils out there, non-synthetic 0W-50 doesn't exist.

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My biggest problem is the brake booster doesn't work when it's 0* and below until the temp warms up under the hood after 5-10mins.

 

- Replace the brake booster hose. It has a check valve that freezes due to condensation. What I used to do is before I moved the car I would pump the brakes a few times to break the valve free then your good to go. If you do it every time the car sits for 4-5 hours or more you wont have an issue.

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My biggest problem is the brake booster doesn't work when it's 0* and below until the temp warms up under the hood after 5-10mins.

 

- Replace the brake booster hose. It has a check valve that freezes due to condensation. What I used to do is before I moved the car I would pump the brakes a few times to break the valve free then your good to go. If you do it every time the car sits for 4-5 hours or more you wont have an issue.

Dumb question but the check valve is located closer to the brake booster right? When I took off the hose I forgot which way it went.

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It is built into the hose

I know that part but I assume the check valve is closest to the brake booster as like you said before it's a one way valve so I assume the engine vac would keep it open so, i think I have it right.

 

oh never mind.. took seconds just to test myself.

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