German Castrol 0W-30 in older Subaru

[spencertimm]

Hi all,

I have been using up my German Castrol 0W-30 I bought last winter over the spring and summer. I am about due for a change, and I have four more quarts left of the GC.

However, I have some reservations about it. First a little background:
I have a 2000 Subaru Outback wagon with about 110,000 miles on the odometer. It does not consume any oil. It does, however, have a slight knock (valves? piston slap?) on cold starts, especially winter cold starts. It goes away after about a minute of driving.

I am worried that the GC 0W-30 is a little too thick for this engine, especially at the colder temps of winter in the Pacific Northwest. I usually am starting it when it has sat outside in 30-40 degree temps. I know that the oil is well within its range at these temperatures, but I would like to hear some other opinions.

I noticed on the M1 website that their standard synthetic 5W-30 has a cSt of around 60 at 40 degrees celsius, and the German Castrol 0W-30 has a cSt of about 72 at 40 degrees celsius.

Is this a significant spread, or should I not worry about it?

Thanks all!

 

[Shannow]

The "0W" is the cold temperature part.

GC will be better at -40C in terms of cranking, and flowing into to oil pump pickup than M1 5W30 will be at those temperatures.

Are you taling -30 degree temps, or only around freezing (30-40).

If the former, keep a 0W if the latter, you could go all the way to 15W without issues.

That being said, GC is a high HTHS multigrade 30 it will have higher KV40 than the M1 5W30, but it's of no real consequence....the 5W30 M1 is an ILSAC economy grade, not the field that GC is playing in.

 

[69GTX]

In Oregon's moderate temps, 5w-30 is certainly thin enough for cold starts, and is probably thinner at operating viscosity than the 0w-30 GC. If you're worried the GC is too thick, the 5w-30 M1 is probably a potential solution as it's thinner when operating. It's a weak 30 weight while 0w-30 GC is a strong 30 weight. What grade oil does Subaru recommend?

At Oregon cold weather 30-40 deg F starts there's probably no perceptible difference in those 2 oils.

 

[Garak]

A 0w-30, even an A3/B4, is not going to be too thin in any weather you're going to encounter. VW/Audi and others started specifying such oils partially so they could have high HTHS for hard operation and still have good winter starting, without changing from 15w-40 in the summer to something else in the winter.

 

[fdcg27]

Do you have the OM for this Subie?
If you do, find the visc/temp chart in the oil recommendations section.
You'll find that while Subaru recommended an energy-conserving 5W-30 for all conditions, they also recommended a variety of other grades.
Suffice it to say that if Subaru thought that you'd be fine using a 10W-30 or 10W-40 down to -4F, GC should be fine for the mild winters you experience in Oregon.
I've also used GC as a winter oil in two Accords with no issues and it gets much colder here than there.

 

[SilverC6]

30-40 degree temps?!?!

Heck, you could use 20W-50 without any cold start concerns.

Go ahead and use that Castrol 0W-30. It's great oil.

Who knows, it might even quiet that noisy Subaru down.

 

[Trav]

The noise is piston slap and nothing to worry about in this engine, they all do it and in the case of most horizontal engines seems perfectly normal and harmless. It bothers you more than it does the engine.
When the GC is done use Rotella T6 5w40 or 0w40.

 

[05LGTLtd]

Run the 0w-30. It's what the wife's 2010 forester gets for 8k oci. No complaints.

In M1 offerings, the 0w40 is a 'thin' 40 so it's pretty close to the 'thick' castrol 0w30 and would be a fine choice too. Subaru EJ engines didn't always agree with m1 5w30 in the SL and SM versions, but the SN version seems ok. I'd still go with the cheapest/easiest of the castrol 0w30 or M1 0w40.

If you can pick up some PUP 5w40 on clearance at AZ, there's a $2 rebate per quart. I just cached 12 quarts. After rebate it is $2/qt.

You'll need another ~1/4qt of oil to go with your four existing quarts, btw.