5w40 completely eliminated cold knock!

Serendipity here. I've usually been a 5w30 guy. My 2.5i has always consumed about 1-1.5 qts between 5K synthetic oil changes. So now, with 80K on it, I decided to try some 5w40 because when I switched to it on my VWs, it almost completely eliminated my consumption. With only 400 miles since the change, it's too early to judge consumption, but something I didn't expect happened in that my cold knock upon start up and cold acceleration is completely gone! The engine sounds so quiet and so good. I didn't expect that because the 5w is the same flow in cold weather and I always thought the knock was the oil not flowing yet too well when cold. Since this has happened, it makes me think the knock was more likely caused by the hot oil draining off the internal engine parts like water when hot, and then having no coating upon start up. The 5w40 is thicker when hot, so maybe it's just thicker enough to leave a coating after shut down. Whatever, I'm liking it.

Oils are not created equal, but don't look for confirmation of this from rao.

Oh I am sure all oils are totally different from one another.

 

OP - you neglected to mention the most important thing - what BRAND of oil are you using?

Itzed - Different oils can do that, even different 5w30s (as you pointed out, they are supposedly within the same range).

 

Whatever, our Subies are ladies with short skirts that like the thicker lube.

Wrong viscosity, your car will blow-up!!!

Whatever, our Subies are ladies with short skirts that like the thicker lube.

 

 

Oh I am sure all oils are totally different from one another.

 

OP - you neglected to mention the most important thing - what BRAND of oil are you using?

 

Shell rotella. I know some people will say its for deisels, but its also gasoline rated. Previous 5w30 oils I used were all synthetic, and included Mobil 1, castrol syntec, and penzoil. It knocked with all of those when it was cold.

Rao - It was Shell Rotella T 5w40...what did I tell you? Is there anything that oil CAN'T do?

 

In fact, a bottle of shell showed up on my front door step the other day. Had a note on it that read, "Hi, my name is T-bone. I'm here to powerwash your siding."

 

Damn fine oil, that Shell.

Rao - It was Shell Rotella T 5w40...what did I tell you? Is there anything that oil CAN'T do?

 

In fact, a bottle of shell showed up on my front door step the other day. Had a note on it that read, "Hi, my name is T-bone. I'm here to powerwash your siding."

 

Damn fine oil, that Shell.

 

I'm old enough to recognize some darn good sarcasm when I see it. Just for clarification, I'm not saying any one brand is better or worse, only making the observation that it's the heavier weight on the hot end that seems to have made all the difference. And I do love that short skirt/heavy lube analogy. I'm going to find a way to throw that into a conversation tonight somehow.

Thanks. Please feel free to credit that to me within the Subie community, if that catches on. And, for that matter, the GM small block community (ahem, Rao).

 

Actually maybe I should modify it to: "Our Subies are ladies with short skirts that like to be stroked with thicker lube."

 

Seems appropriate.

 

Actually maybe I should modify it to: "Our Subies are ladies with short skirts that like to be stroked with thicker lube."

 

 

Perhaps that's why they are appealing to Lesbians?

This is what I use in my older 2.2 engines. Have been for a few years now. Oh yeah, Valvoline Premium Blue synthetic.

Perhaps that's why they are appealing to Lesbians?

 

The dealer I bought my used 05 from told me it was a one owner car, a lesbian couple. I said SOLD!!!

 

Oh yeah, forgot what the thread was about. My Subie enjoys the Castrol Syntec 5W40.

I thought the climate was important on which weight of oil you should use. If I am not mistaken, colder areas should use a heavier weighted oil?

I thought the climate was important on which weight of oil you should use. If I am not mistaken, colder areas should use a heavier weighted oil?

Opposite. Cold(er) climates tend to use lighter weight oils.

Remember the weight of the oil also impacts how hot it gets. Higher weight oil = cooler running temperature. Too "thick" and the oil may not get to target temperature.

More in the Oil manifests.

Remember the weight of the oil also impacts how hot it gets. Higher weight oil = cooler running temperature.

 

Sorry, but this part is not correct and is so application dependant that it can't be broadly brushed.

 

Some thicker oils will actually get and stay hotter due to reduced flow/more time spent on hot surfaces. Again, really application dependant.

Sorry, but this part is not correct and is so application dependant that it can't be broadly brushed.

 

Some thicker oils will actually get and stay hotter due to reduced flow/more time spent on hot surfaces. Again, really application dependant.

 

Great point; from what I have read all of the SAE and API specifications are actually more like suggestions and are completely meaningless

Rao - Like so many things in life, broad ranges do become meaningless in the context of specific statements and when not put against any particular context.

I totally agree. Each oil must be laboriously evaluated - it's not like you can just go into a store and pick up an oil that meets the manufactures' specifications. Those specifications themselves are suspect.

 

I'm so glad you understand! If someone had, say, used the specification of oil Subaru recommended in 2005 for the Legacy GT, and the oil change interval recommended.....well, bad things would likely have happened!

 

Hence why it's important to ignore manufacturer recommendations and carefully evaluate your usage and oil selection.

 

So glad we are in agreement

Certainly. I also have all oil and all other automotive fluids analyzed before I put them into any car - that is the only way to know if they meet the specifications (as you know the variance is so large that you can never be too careful) and the only way to have a true baseline for after-use analysis. It is a bitch with gasoline, but i t is one of the sacrifices that I gladly make to have a superior performing automobile.

You guys are the reason why newcomers get worried about whether or not M1 will destroy their engines.

You guys are the reason why newcomers get worried about whether or not M1 will destroy their engines.

 

After reading all of the oil posts, I think it would be best to drain the oil and drive around with nothing in the crankcase

Sorry, but this part is not correct and is so application dependant that it can't be broadly brushed.

 

Some thicker oils will actually get and stay hotter due to reduced flow/more time spent on hot surfaces. Again, really application dependant.

Interesting angle, all the research I did in the past ( both motorcycle and automobile ) showed a decrease in temp with higher viscocity lubricants.

Now granted it was same-vehicle mules under controlled testing parameters. Good info to chew on!

FWIW I switched to the Rotella-T 5w-40 on my last oil change. Ran regular Castrol for years on my V-8 motors ( 3000 mile OCI on average ). Tore down a few of them, clean with little/no bearing wear. So what does it mean?!? Good maintenance practices mean more than the brand oil OR filter you use...

After reading all of the oil posts, I think it would be best to drain the oil and drive around with nothing in the crankcase

 

So now it's "Our Subies are ladies with short skirts that like to be stroked with no lube?"