Any reason not to go w/ the 0w equivalent?

[bagtagley]

Given the past and recent discussion regarding Mobil 0w30 vs 5w30, I'd like to exclude it from this question.

In my specific application, I'm referring to oils where the 0w starts lower on the VI curve than the 5w equivalent, but is similar at operating temperature (Red Line, for example). I know the viscosity curve is merely an estimate, but, in the case of Red Line, it shows the 0w being thinner right up to operating temp, when it is just slightly thicker (.3 cST) than the 5w. In light of that, is there any reason not to get the oil that will flow better at startup and warmup?

 

[StevieC]

Assuming that they aren't using a ton more VII's to achieve this lower 0w rating I see no disadvantage. If they are then the disadvantage is that it's more prone to shear. So the ideal situation would be to go with a 0w with a very high HTHS rating like Redline to prevent shearing from happening so it remains in grade through the OCI.

 

[demarpaint]

I see no downside. Having said that I was told by two oil companies that in older engines a 0w-xx oil could be a little more prone to leaking.

 

[addyguy]

Having to pay synthetic prices - there aren't any 'conventional' 0W-30's.

 

[Kaboomba]

I think the biggest issue with oh-dubs can be finding one that your engine likes across the full range of operating temps, since the temp-to-viscosity relationship can vary among mfrs, etc.

 

[StevieC]

There might be soon with the GF-5 oils demanding so much in terms of performance so some syn may have to be blended in to meet these requirements so they might be able to offer a 0w30.

 

[d00df00d]

Originally Posted By: StevieC
Assuming that they aren't using a ton more VII's to achieve this lower 0w rating I see no disadvantage. If they are then the disadvantage is that it's more prone to shear.

Exactly.

 

[J. A. Rizzo]

The primary disadvantages I know of have mostly already been mentioned, but they include having to pay synthetic prices, possibility of more VIIs and higher potential for shearing, generally lower HTHS values, and the one I haven't seen yet is higher volatility than 5W or 10W products. The volatility probably isn't a big issue, but there can be implications for valve and intake deposits depending on the vehicle and what the volatiles are comprised of. With API SM oils, I think it's less of an issue than it was in the past.

 

[ARCOgraphite]

Many folk don't need a -35C cold flow properties - so why pay for them. It may guarantee you are buyuing a "real" synthetic oil though, if passenger car synthetic has any worth to you.

 

[Jasper8146]

Although it's been mentioned, I thought I would expand on the HTHS difference. I looked at a lot of numbers trying myself to decide between 0W-20 and 5W-20 for an Acura and 5w30 and 0w30 for a Mini Cooper. In most cases, even if there was the same or virtually the same operating viscosity, there was always a difference in the HTHS number, with HTHS being lower every time in the 0W weight. Sometimes the difference was surprisingly large, but the amount of variation depended on the brand. Since HTHS, in my understanding, is a measurement of oil film strength, how important that number would be would depend upon the vehicle and how it's driven, I would think. For example, in Redline, the 5-30 has a 3.8 HTHS and 0-30 has a 3.3. Although the 3.3 is a hair under the 3.5 required for the ACEA A3-B3 standard recommended by Mini, I'm going with the RL 0-30 because our vehicle is never driven hard. On the Acura however, the RL 0-20 is 2.7 and the 5-20 is 3.2 or 3.3, I can't remember which. That is so much of a difference I think I'm going to continue to go with the 5-20 here in Kansas. In Canada, I'd probably make a different choice.

 

[bagtagley]

I thought I read that Red Line didn't use VII's? What about RLI?

 

[StevieC]

Redline doesn't in most of its oils but does in some but in minor amounts as I understand it so it's really a non-issue.

RLI does use them but in small quantities like Redline.

 

[Robenstein]

Other than price I say no reason not to. Unless you live in a warm climate where you really dont need the extra low pour point of a zero weight oil cold.

 

[jstutz]

As stated above, most of the time the 0w30s have a lower HTHS than there 5w30 brothers. Do you want better very low temp performance or better HTHS.

 

[iunderpressure]

If you have an oil with a high HTHS say over 3.5, but the oil was a 0w10 weight, could you safely run it in a car that calls for a HTHS of 3.5 and a 30 or 40 weight oil? So basically what I'm asking is does the weight really matter if you have the HTHS?

 

[jmb106]

Originally Posted By: StevieC
Assuming that they aren't using a ton more VII's to achieve this lower 0w rating I see no disadvantage. If they are then the disadvantage is that it's more prone to shear. So the ideal situation would be to go with a 0w with a very high HTHS rating like Redline to prevent shearing from happening so it remains in grade through the OCI.

I agree!

 

[mechtech2]

Costs.

 

[Spyder7]

Cost & availability. The synthetic oils I've been finding, where I am, on sale are 5W or higher. The 0W selection is more limited here, and they cost more.

My winter oil this year is looking good enough for a 5W30 (PP): it has a -49 PP and its cold crank score is excellent as well. NOACK is a little high, relative to some other syns, but in cold winter operating temps that's a moot point to me.

I see not enough incentive to switch to a 0W for me personally. Maybe next year the market will dictate otherwise.

-Spyder

 

[Gary Allan]

Originally Posted By: iunderpressure
If you have an oil with a high HTHS say over 3.5, but the oil was a 0w10 weight, could you safely run it in a car that calls for a HTHS of 3.5 and a 30 or 40 weight oil? So basically what I'm asking is does the weight really matter if you have the HTHS?


You won't find a 0w-10 oil with a high HTHS.

I look at HTHS as a durability spec ..right along with volatility. I don't look at it for its stand alone level. People like to imagine that some parts of their engine are routinely at that temp, but no matter how you manage to measure it ..on some time weighted average, if that were the case, your sump would be toast and everyone would be consuming oil due to the volatility (measured at the same 150C temp) in very few hours of operation. Now there are some who do see these temps, but they are extremely rare for what most of us consider normal service ..and outside of everyone's propensity to consider themselves unique, I'd say that it's rare for even what some would call severe duty. This is why, or so I reason, why in most cases where truly severe duty is experienced, there's no recommendation to up to a higher HTHS fluid, but rather to shorten the OCI.

 

[21Rouge]

Originally Posted By: addyguy
Having to pay synthetic prices - there aren't any 'conventional' 0W-30's.


But as you had pointed out to me there are synthetic blends that are 0W30 which narrows the price gap.

Heck PC 0W30 is a full synthetic (albeit GRP III) and one can buy it for well under $6 a litre.