Synthetic: Use the LOWEST 1st number available ?

[A_Harman]

Don't get sucked in by the pattern of numbers in the SAE low-temperature viscosity grading system. Here are the limiting specifications:

0W = 6200 Maximum cranking vis @ -35C
5W = 6600 @ -30
10W = 7000 @ -25
15W = 7000 @ -20
20W = 9500 @ -15

Notice the 35% jump that SAE allows for only a 5C increase in temperature that occurs between 15w and 20w. So even though the w-number doesn't change much, it's a big difference in cold cranking viscosity.

 

[CATERHAM]

What manufacturer recommends M1 15W-50?

You might find the following post of some value:
http://www.bobistheoilguy.com/forums/ubb...279#Post2226279

 

[lomez]

the recommendation is for 10W40, but that's just the generic recommendation, for everywhere on earth. Since I live in the SW US, where it gets to 110 ambient, 50 is where I need to be on the hot side. This is probably why they say 20W50 for climates that stay above like 50 degrees F. They realize that a larger spread, say 5W50, would degrade to a 40, where the 20W50 probably would not. My goal is a 0W50 that will not degrade to a 40 weight at operating temps, except after 3,000 miles or something. That's the oil I want to use. Running a 20W50 is just too heavy to get on the gas until the oil gets all the way up to temp. In fact, I wouldn't want to do more than idle.

 

[Quattro Pete]

Originally Posted By: lomez
In my motorcycles, I run Eneos 0W-50 with SM API service (while the manufacturer recommends 20W-50 in summer).

What motorcycles? Do they have wet clutches? If so, you should be running oil with JASO MA certification.

 

[lomez]

wet clutch. Dl1000 for example. never had a problem

 

[CATERHAM]

Okay so this is presumably a sportbike application.
I'd stick with 4T oils of the 10W-40 grade.
In your climate, comparing the KV40 spec's from the oil companies PDS is the best way to determine the lowest start-up viscosity. You could go with a 5W-40 but most of my biker freinds find the 10W-40 grade to be more shear resistant and therefore maintain a higher operational viscosity.

 

[lomez]

Originally Posted By: CATERHAM
Okay so this is presumably a sportbike application.
I'd stick with 4T oils of the 10W-40 grade.
In your climate, comparing the KV40 spec's from the oil companies PDS is the best way to determine the lowest start-up viscosity. You could go with a 5W-40 but most of my biker freinds find the 10W-40 grade to be more shear resistant and therefore maintain a higher operational viscosity.


Even knowing that ambient temps WILL get to 100-115 F in the summer? I mean, I've driven across the Mojave desert where it was 115 the entire time. You wouldn't jump to a 50 under these conditions? Just wondering.

 

[Steve S]

I hope you are not reading oil 101 and using the authors opinion as fact.

 

[vinu_neuro]

You guys realize that Mobil1's racing oils are 0W right? It's a fallacy that 0W oils are less stable. Look at M1 0W-40 and it's using in 24hr endurance racing. In the 24hr of Le Mans M1 0W-40 covers 3000 miles+ of continuous racing.

 

[glum]

1. Don't all 0W-X oils have VMs/VIIs?

2. Doesn't the presence of VMs/VIIs mean less base oil?

3. If yes, isn't it a trade-off to add more VMs/VIIs?

 

[Gokhan]

According to the Exxon - Mobil synthetic-lubricant recipe book, not only that synthetics have viscosity-index improvers (VIIs) but Group IV synthetics have more viscosity modifiers than the Group III/Group IV or Group II+/Group IV synthetic blends.

Therefore:

Myth 1: Group IV synthetics have no VII: false
Myth 2: Group IV synthetics are better than Group III synthetics: false
Myth 3: Synthetics have always less VIIs than dino: false
Myth 4: Group IV synthetics have always less volatility than Group III: false

If you go through the Mobil recipes linked above, you will see why these myths are false.

This is not to say that all synhetic oils have VIIs; there might be Redline or such that have none but chances are that Mobil 1 etc. that you are getting have plenty of VIIs; in fact possibly more VIIs than good dino oils.

Coming to the first question: No, 0W- is not necessarily better than 5W- or 5W- is not necessarily better than 10W-. Yes, the fuel economy and cold-start performance will be better but there will be compromise with the NOACK volatility, high-temperature performance, and oil durability. This is not to say that there is no 0W- oil out there that outperforms 5W- oil in all respects but just be cautioned and at least check to see if the oil meets all the manufacturer standards you need.

Bottom line: Oil blending is more of an art than science. Oil manufacturers will blend things any way they want and chances are that you aren't getting what you think you're getting. Synthetic, Group IV, etc. have little meaning and your best way to ensure that you're getting a good oil is to make sure that oil officially satisfies the standards you need, you looked at UOAs, and went through the user posts here about others' experiences (which you should take with a grain of salt). Then you can buy and try it and even do your UOA and be your own judge.

 

[CATERHAM]

Originally Posted By: lomez
Originally Posted By: CATERHAM
Okay so this is presumably a sportbike application.
I'd stick with 4T oils of the 10W-40 grade.
In your climate, comparing the KV40 spec's from the oil companies PDS is the best way to determine the lowest start-up viscosity. You could go with a 5W-40 but most of my biker freinds find the 10W-40 grade to be more shear resistant and therefore maintain a higher operational viscosity.

Even knowing that ambient temps WILL get to 100-115 F in the summer? I mean, I've driven across the Mojave desert where it was 115 the entire time. You wouldn't jump to a 50 under these conditions? Just wondering.

In a liquid cooled sportbike I don't think you can do any better than Motul 300V 10W-40, M1 4T 10W-40 or Amsoil 4T 10W-40.
These oils are used in racing so I don't think you're going to have anything to worry about even on a high speed blast through the canyons or the desert in S.Cal.

 

[fdcg27]

I think you have the right idea, but I think you might be going about it from the wrong side.
A thin oil is desirable at start-up, but how much of your time is spent at low oil temps?
A thicker grade might be desirable at sustained high temps, but do you really know how hot the bulk oil temps of your engines are in sustained running at high ambient temps?
You do understand that a really wide spread requires the use of VIIs, whether the oil is labeled synthetic or not?
Therefore, maybe you should look at the operating temperature of the oil in your engines, and based upon that, decide just how thick a grade you need to use, while minimizing the spread.
I gather that you are primarily looking at oils for bikes.
Many users do well with dual rated 15w40s.
The time you'll spend at the thick and cold end will be brief compared to the time you'll run the engine at operating temperatures.
Engines do wear.
They're made to.
Any reasonable oil changed on any reasonable interval will allow the engine to outlast the rest of the machine, at least in terms of wear.

 

[lomez]

Well, my entire strategy (lowest "cold" number possible when using a synthetic, so long as the hot # meets your 100 C need) and theory is based on the simple statement (read on this site and other places), that "pure synthetic oils use NO viscosity modifiers.....and will NEVER degrade into an oil which is less than their 100 C viscosity rating states" BITOG: synthetics are a different story

So, assuming this is not always the case, and that many, perhaps most synthetics use modifiers to obtain a viscosity range, then I have to adjust the whole approach. This is the case since we all know that the modifiers are 1) taking a naturally thinner oil, and making them act like a thicker oil at temperature; and 2) will degrade over time and use. Thus, over time, a 0W50 is probably a thinner oil than a true 50; and, will degrade to a 0W40 or worse over time. But again, this is assuming that all synthetics with more than a xx "range" in cold-hot viscosity will use modifiers.

I just dumped what I have in there and replaced with some 20W50 Motul. I guess I'll just get used to warming the bike at low rpm and zero load until the oil is warm. I guess that's the best strategy for cold oil operation rather than using a 0weight oil?

 

[lomez]

Originally Posted By: fdcg27

The time you'll spend at the thick and cold end will be brief compared to the time you'll run the engine at operating temperatures.


Yes, but its pretty universally accepted that the vast majority of wear happens during COLD operation, because the oil is not flowing. That was the whole point of my strategy. However, IF pure synthetics also have the modifiers which will degrade over time, and thus negatively affect the high-temp (100 C) viscosity of the oil....then I don't think I want the trade-off. Or do I? It gets complex when you start considering sheer and how that's affected when/if a 0W40 degrades to a 0W30 in an engine that asks for a 40W at temp.

 

[lomez]

Originally Posted By: lomez

I just dumped what I have in there and replaced with some 20W50 Motul.


make that 15W50 Motul...just in case it matters

 

[CATERHAM]

You really are on the wrong track.
Firstly it is a newbie mistake to look at the SAE grade and not the underlying viscosity spec's of the actual oil in question.
Secondly, if you read the link to the post I mentioned, you'd know that the first number of the SAE grade (XW) only applies to the sub zero celcius performance of an oil and it is the viscosity index (VI) that determines how thick or light an oil will be at temp's above freezing; the higher the better.

Finally, when a manufacturer spec's an oil grade you can rest assured ambient temp's of at least 120F are factored in along with oil temp's higher than what you can possibly generate on the street. Your choosing to run a grade heavier than spec' has no logical basis.
You haven't mentioned the make and model of your bike, but if you have concerns it would make sense to contact the manufacturer regarding the adequacy of the recommended oil grade.

 

[lomez]

Originally Posted By: CATERHAM
You really are on the wrong track.
Firstly it is a newbie mistake to look at the SAE grade and not the underlying viscosity spec's of the actual oil in question.
Secondly, if you read the link to the post I mentioned, you'd know that the first number of the SAE grade (XW) only applies to the sub zero celcius performance of an oil and it is the viscosity index (VI) that determines how thick or light an oil will be at temp's above freezing; the higher the better.

Finally, when a manufacturer spec's an oil grade you can rest assured ambient temp's of at least 120F are factored in along with oil temp's higher than what you can possibly generate on the street. Your choosing to run a grade heavier than spec' has no logical basis.
You haven't mentioned the make and model of your bike, but if you have concerns it would make sense to contact the manufacturer regarding the adequacy of the recommended oil grade.



Yea, I get all that, and I did read the link you sent. I was just using jug label #s for reference purposes. I can't find detailed viscosity information for oils, so that I can compare viscosity at different temps. Where can I find detailed viscosity/temp specs?

The bike I'm currently dealing with is a Suzuki DL1000, v-twin. The manual calls for 10W40. However, it also says that "if 10W40 is not available, use a different grade according the the chart below"......this chart indicates 15W40, 15W50 and 20W50 would be acceptable with ambient temps above 15 F. So, I gather a xW50 is perfectly acceptable in terms of protection at operating temps, in the SW US, in summer. Correct? Incorrect??

I used a 15W50 Motul (300V 4T). Again, I'd like to be able to compare 75 F and 212 F thickness for different oils, including Motul.....but can't seem to locate such a thing. Any thoughts on a 15W50 Motul?

 

[Gokhan]

The two most critical viscosities are cold-cranking viscosity and HTHS viscosity. 20W-50 oils usually have an HTHS viscosity of 4.5 or higher. Mobil 1 15W-50 has an HTHS viscosity of 4.5. Pennzoil Platinum has a lower HTHS viscosity of 4.1.

Since 20W-50 is recommended for your bike for the summer, any conventional or synthetic 20W-50 should be fine for the summer.

For winter, if your temperatures don't go below freezing, you can simply stick with a conventional or synthetic 20W-50. For colder temperatures, use a synthetic 15W-50 with a high HTHS viscosity (such as Mobil 1). For really cold temperatures (that you won't dare riding a motorcycle at), a good 5W-40 synthetic with a high HTHS (~ 4.0 or higher) should be fine.

This is not rocket science. In fact, you can use the Mobil Delvac 1300 Super 15w40 (HTHS viscosity 4.3) I am using throughout the year and you will be just fine.

 

[Gokhan]

Originally Posted By: lomez
The manual calls for 10W40.

I thought you said 20W-50 in your original post. If it says 10W-40, why don't you use 10W-40? There is no reason to go to higher viscosities, which will put more stress on your engine and reduce your fuel economy, unless your engine isn't working well with the recommended viscosity (oil consumption, wear problems, etc.).

A conventional 10W-40 would be just fine in your case. In Southern California you would really never need a 5W-40 or 0W-40 oil for cold starts.

You can use Rotella T6 5W-40, Delo LE 5W-40, or similar synthetics but there is really no need, unless you're trying to achieve longer oil-change intervals.

You can also experiment with fancy synthetic 0W-40/5W-40/10W-40 oils such as Amsoil, Redline, Royal Purple, etc. at your $$ expense if you like experimenting.

If you want to pick up an xW-40 out of a bunch, choose it based on HTHS. It's always a difficult compromise: larger the HTHS less the fuel economy, more stress on the engine, less protection on the piston rings, but more protection on the bearings; smaller the HTHS more the fuel economy, less stress on the engine, more protection on the piston rings, but less protection on the bearings.