Idea for picking right oil?

[mark pruett]

So I've been thinking about how to choose the correct oil for my truck.

Since I live in Dallas, and almost never see temps lower than about 15-20F, and most of the time, the startup temperatures range from the upper 20s to about 80, depending on the time of year, I got to wondering if worrying about the Xw-Y viscosities is really the important thing.

My thinking is that possibly the 40C viscosity is the one that's really the more useful one to look at for startups - it was pretty close to ambient for the last month or so.

Even when it's not ridiculously hot, 40C is a lot closer than 100C to startup temps, and I may be wrong, but the Xw viscosities are measured at a considerably colder temp than 20F.

So assuming that the oil meets the right SAE grade (30) for my truck, I might actually be better off in terms of practical startup viscosity if I get the one with the lowest 40C viscosity, all else being equal.

Does this hold up? Or do the temp/visc curves really vary that much between oils? Or is there another reason that this wouldn't stand up?

 

[Eddie]

In a theoretical sense you are correct but, in the real world, I think it makes no difference. Within grades you don't find much difference in the vis-temp curves from what I have seen.

 

[ARCOgraphite]

What are you trying to accomplish with the oil? Less startup noise? Lower warmup viscosity that may lead to improved economy? There are so many things an oil has to do, and can do, I wouldnt focus on just one spec unless y ou are trying top correct a specific problem. Note that some oils use better base stocks and additive in their 5w than the 10w.

 

[StevieC]

Good quality dino year round would be my choice... Try them all to find what gives you the best sound, engine smoothness and best UOA and sleep good.

 

[Steve S]

Why the worry about the startup viscosity when there is no worry about below 0f* ? a 10W-XX dino oil will be good to 0*f. easy. 5w30 even better.

 

[mechtech2]

When you have a lower viscosity at 0 F, you generally are a bit lower at mid temperatures, also.

For instance: a 0-30 vs 5-30 vs 10-30:
The 0-30 is thinnest from 0F up to operating temp -212F
The 5-30 is thicker all the way, but the same or similar at 212F.
And the 10 -30 is of course even thicker in all ranges up to the 212F point.
Which one to use in the Dallas area?
Zero difference in real life.
One thing - 0-30 and 5-30 are more modern, and may provide incidental benefits from their compilation.

 

[ARCOgraphite]

In Dallas, I would say you dont need a 0W/5W . Pick a 10w30 with the highest VI and you got what you are asking for - a flatter viscocity 'CURVE'.

 

[sicko]

Idea:

Step 1) Check what weight oil is recommended in the vehicle's owner manual.

Step 2) Use that weight oil.

Step 3) Start the never ending journey of deciding what oil of that weight you should be using.

 

[Spyder7]

You summed it up nicely in my case, at least. Manual approved grades are 5W30 and 10W30, with 5W30 being recommended. Now I find myself wanting something a little thicker than most 5W30s, but not as thick as the average XW40.

I've been lost ever since.

I'm starting to think the solution to everything I'm looking for in an oil will be found in a 5W30 HM oil. Only down side is they rarely go on sale, so at regular price I'd pay double what a good conventional dino costs. That and I have yet to find a good comparison amongst them to decide which way to go. Anyway its a moot issue right now. I'm still a few OCIs away from going that route if I'm ever going to.

-Spyder

 

[shpankey]

Originally Posted By: ARCOgraphite
In Dallas, I would say you dont need a 0W/5W . Pick a 10w30 with the highest VI and you got what you are asking for - a flatter viscocity 'CURVE'.

Out of curiosity (rather ignorance on my part really) what does a higher viscosity index do for one?

 

[shpankey]

Originally Posted By: Spyder7
You summed it up nicely in my case, at least. Manual approved grades are 5W30 and 10W30, with 5W30 being recommended. Now I find myself wanting something a little thicker than most 5W30s, but not as thick as the average XW40.

I've been lost ever since.

I'm starting to think the solution to everything I'm looking for in an oil will be found in a 5W30 HM oil. Only down side is they rarely go on sale, so at regular price I'd pay double what a good conventional dino costs. That and I have yet to find a good comparison amongst them to decide which way to go. Anyway its a moot issue right now. I'm still a few OCIs away from going that route if I'm ever going to.

-Spyder


I think you have a good idea. I'd say the M1 10w30 HM. It's only $21 for a 5 qrt jug at walmart has a great HTHS rating and awesome specs all around.

You could also go with GC.

 

[CATERHAM]

Mark, I agree with your thinking.

But keep in mind that the 40C vis' spec' is a kinematic measure that is at best a ball park figure when comparing oils but not accurate in absolute terms.
Take M1 AFE 0w30 for example. It's kinematic vis spec's are quite high; 40C KV 63.1 cSt, 100C KV 11.0 cSt but it likely is the lightest 30wt oil at ALL start-up temp's on the market.

 

[Eastexan]

Since I'm just a novice, some of what you all say just goes over my head, so pardon me if this question sounds stupid, but if 90% of engine wear is at startup, as some claim, wouldn't it be best to use a 0W oil at all times?
Since parts are starved for oil at startup and needs the oil to get there ASAP, I would think that the oil needs to be as thin as possible to get there quickly.

 

[mechtech2]

East - Yes.
That is why some say, "No oil is too thin at start up".

 

[HTSS_TR]

"wouldn't it be best to use a 0W oil at all times?"

Yes, but 0Wxx oils that you can buy on the shelve are synthetic only and very few is available, at least for now.

 

[CATERHAM]

Yes indeed.
Of course a 0w30 is lighter at start-up than a 0W-40 and 0W-20 is lighter still.
Then there are thick 0W-20's (Amsoil) and thin 0W-20's (Castrol Edge).

So Mark's suggestion of checking out the 40C vis KVis spec' is a good place to start.

 

[Tempest]

Originally Posted By: Eastexan
Since I'm just a novice, some of what you all say just goes over my head, so pardon me if this question sounds stupid, but if 90% of engine wear is at startup, as some claim, wouldn't it be best to use a 0W oil at all times?
Since parts are starved for oil at startup and needs the oil to get there ASAP, I would think that the oil needs to be as thin as possible to get there quickly.



Start up is more than just cranking the engine. It's the entire warm up cycle. That's why having a super thin oil just for start up is something of a misnomer.

 

[Patman]

In the past year or so I've been finding myself a little bit more obsessed with finding oils that have lower 40c viscosities as well. I almost cringe now at the thought of the 40c viscosity of GC 0w30, which is in the low 70s! That's a big difference compared to the oil I run in my wife's Honda now, which is a 40c viscosity in the low 40s. For cars like hers that do mostly shorter trips, I think it's important to have an oil with a low viscosity at 40c.

I'm actually looking forward to the day when 0w10 oils start coming out, as I have a feeling most of them will end up with 40c viscosities in the low 30s!