0w, oil cooling and other questions

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Gards

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May 29, 2005
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Hello all you grease monkeys out there.

Ok so ive been using Motul Turbo lite 10w/40 semi-synthetic on my 97 Swift GTI with 128xxxkms for about 1 year with 5000km oil changes. Havnt had any issues and my engine seems to be in great shape.

Anyways after getting a forum members opinion of this oil he said it isn't anything special for the price.

With the release of Castrol's Edge range of synthetic oils my eyes opened to their 0w/40 product. I think these castrol products use a higher base synthetic group than the motul and I love the sound of 0w starting up. It costs 70$ compared to $45 but considering I will be taking the car occasionally to the track and strip as well as my usual combo of spirited street driving better protection (if any) is worth the extra money.

Also being pretty busy these days I don't always have the time to change the oil as I found recently when I hit the 5000km mark. So even slightly extended drain intervals could be of benefit to me to give me the peace of mind the engines still being protected well with the synthetic.

Does anyone have some viscosity charts of these 2 oils so I can tell e.g. if one is a heavy or light 40?

Now some questions.

Firstly in regards to the 0w at startup. I read on a viscosity chart about 0w flowing at -30 cranking. because I dont live in the artic my car will never see such low temperature starts. Possibly at worst 5 degrees on a rare freezing winters morning. Will the 0/w's superior cold flow temperature properties still be an advantage over say the 10w even if the temperature never hits freezing temperatures or that -30 degrees for instance. I.e will it generally flow quicker than the 10w at any given cranking temp?

Can the 0w make starting the car easier when cold?

Secondly like most engines im pretty sure mine uses that system of splashing oil around to help lubricate parts. One member suggested a heavier weight can be better at startup because this flung oil sticks better to parts while another member suggested that a lighter oil will splash further and easier. Does anyone know the correct theory behind oil splashing and its relation to the oils wieght. However considering my recent learning that the first number doesnt relate to weight at all but purely flow perhaps this whole argument is irelevant if thinking in cold startup terms.

Secondly I plan to get an oil cooler installed. From what ive read these can lower oil temps by %10. Can this have a thickening effect on the oil? E.g. essentially causing a 40 weight to become 45? Same deal with electric water pump im going to intall which can decrease engine/coolant temps, perhaps this will thicken my oil a little to? Anything I should know in this regard.

Thirdly I was planning on doing a UOA on both these oils to compare them. There seems to be some critism of UOA in terms of determing a engines condition however a UOA is still useful in comparing the performance of 2 oils right? Or are there too many variables to make an accurate conclusion? I'm guessing im going to get some varied responses to this question. heh.
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Thanks for your input and time.
 
I couldn't find any visc data on Motul's site. They don't appear to publish the product data
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Secondly I plan to get an oil cooler installed. From what ive read these can lower oil temps by %10. Can this have a thickening effect on the oil? E.g. essentially causing a 40 weight to become 45? Same deal with electric water pump im going to intall which can decrease engine/coolant temps, perhaps this will thicken my oil a little to? Anything I should know in this regard.

Any temperature alteration will change the oil's viscosity. Without temp data and the visc spec's of the oil ..there's no way to figure where the visc will end up. You may be at the bottom of the 40 range normally ..and when cooled fall in the mid/upper end. Who knows
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Install an oil temp gauge and see what your temps are in various modes of operation.
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0W-xx isn't necessarily less-thick than a 5w-xx, except at the very lowest temps. The 0w-xx will show movement when tilted at minus 30-something, whereas the 5w-xx no longer shows such movement. Fast forward to 10 degrees C, the 5w-xx MAY be thinner than the 0w-xx, same at 20 degrees C, etc. That "w" number isn't really referring to viscosity...it's referring to movement when tilted at very cold temps. Since all engine oil is TOO THICK at start-up, you want the best-flowing oil at your normal ambient temps for best start-up protection...you'll have to compare temp/visc charts for oils to be able to determine which is best for your conditions. Faster flow is a better startup protectant than a film left behind since you last turned off the engine. There's not THAT MUCH difference in operating temp viscosity between a 20 weight and a 40 weight, so either drains off the engine parts easily at shutdown....however, there can be a big difference in their respective cold viscosities...THAT is where the thinest ambient viscosity is most important.

If you have a 40 weight oil, using a properly functioning oil cooler will not result in the oil being thicker. Sure, the hotter the oil, the lower the viscosity, but, a 40 weight at 100 C is a 40 weight. You don't want your oil too cool, you just want to make sure it doesn't exceed some pre-determined temperature. Make sure your oil cooler has a thermostat so you get to at least 180 F. 200 F might be even better. Seems I've read that maximum efficiency occurs somewhere around 212 F....but, not sure maximum efficiency is what you are looking for. With regard to oil temp, remember, it depends upon where you are measuring the temperature!


Electric coolant pump...not going to have an effect on your sump temp, unless your previous cooling system was faulty or inadequate for your conditions.

UOA usefulness: It depends on your ability to understand the numbers. If it's just a bunch of numbers to you, it's meaningless. Terry Dyson seems to be able to make sense of the numbers, so, to him, a UOA is chock full of valuable information.
 
quote:
Originally posted by Titan:
0W-xx isn't necessarily less-thick than a 5w-xx, except at the very lowest temps. The 0w-xx will show movement when tilted at minus 30-something, whereas the 5w-xx no longer shows such movement. Fast forward to 10 degrees C, the 5w-xx MAY be thinner than the 0w-xx, same at 20 degrees C, etc. That "w" number isn't really referring to viscosity...it's referring to movement when tilted at very cold temps.
Click to expand...
Titan are you saying that oil companies don't use any type of measuring equiptment to determine their products viscosity? Are you saying it's determined by a formulator or tribologist or janitor that picks up a container of oil that has been cooled to a certain temperature and tilts it then measures the movement of the oil and assigns a viscosity to it? Please clarify this for me because I have been under the impression that they had labs full of equiptment and highly trained professionals to measure an oils ability to flow at various temperatures.
 
quote:
Titan, explain what all oil is TOO THICK on startup means?
Click to expand...
Your engine was designed for an oil with a viscosity of 10-12 centiStokes. Your engine does not care if the oil is at -50dF or +200dF it wants a 10-12cSt oil. This is the viscosity where the oil flows at a rate that will properly cool the various parts, and be thick enough to support the loads and prevent metal-to-metal contact; thus minimizing wear.

Even the thinnest 5W-20 oil is above 36cSt at 100dF (40dC) and is thicker than what your engine wants.
 
quote:
Originally posted by farrarfan1:

quote:
Originally posted by Titan:
0W-xx isn't necessarily less-thick than a 5w-xx, except at the very lowest temps. The 0w-xx will show movement when tilted at minus 30-something, whereas the 5w-xx no longer shows such movement. Fast forward to 10 degrees C, the 5w-xx MAY be thinner than the 0w-xx, same at 20 degrees C, etc. That "w" number isn't really referring to viscosity...it's referring to movement when tilted at very cold temps.
Click to expand...
Titan are you saying that oil companies don't use any type of measuring equiptment to determine their products viscosity? Are you saying it's determined by a formulator or tribologist or janitor that picks up a container of oil that has been cooled to a certain temperature and tilts it then measures the movement of the oil and assigns a viscosity to it? Please clarify this for me because I have been under the impression that they had labs full of equiptment and highly trained professionals to measure an oils ability to flow at various temperatures.
Click to expand...
I'm guessing the tilting remarks were just an example.

The key is, a 0W oil while having better cold cranking performance and pumpability at very low temperatures may in fact be thicker than a 5W or 10W oil at any more normal temperature.
 
jsharp you might be right I don't know. I was intrigued by his last sentence that says "w" isn't referring to viscosity, it's referring to movement at very cold temperatures. That implies someone has to look at it and then assign a number to it based on how much it moves or doesn't move at "-30 something" when the bottle is tilted. Seems rather subjective and inaccurate to me.
 
The "w" grades are binary (pass/fail). An oil must have a viscostiy less than X at temp Y. The minimum viscosity and the temperature at which it is measured varies by grade. I think that the measurment is made with a rotary viscometer.
 
Titan was right on with that first paragraph on 0W vs 5W. For an example, consider the viscosity of an oil at 10F. GC (0W30) oil is thicker at 10F than almost any other 5W30. At some temps GC is thicker than some 10W30 oils. That is because GC is fairly thick at 212F. It's cold flow properties do not really shine until you reach the below 0F temps.

As far as the oil cooler making your oil to thick. I feel that is a possiblity on cold days. When you have an oil cooler your oil temp could be below optimum. However, as Titan said, if your oil cooler has a thermostat, then it would not be a problem.

The best way to find out what is happening to your oil temp is to get an oil temperature gauge. That will help you determine whether you need a cooler and will help you pick the proper viscosity.

Some examples:

code:
TEMP GC 0W-30 M1 5W30 M1 10W30

C SM SM

-35 12061 12508 19610

-30 6947 7110 10423

-20 2609 2612 3424

-10 1127.1 1109 1332

0 546.6 531 595

10 291.8 281 298

20 168.8 161 156

30 104.4 99 95

40 68.4 64.8 62

100 12 11.3 10


Click to expand...
 
Ok guys thanks that answers my main question of whether a 0w would be useful and I guess the conclusion is that it probarly wouldn't be and that the recommended 10w startup is likely the best for cold flow although in summer maybe not but the 10w should still be pretty close and work well.

Very interesting conclusion this after reading an article suggesting in all circumstances the lowest cranking W should be sought after.

So I'm basically saying stuff the Castrol, Ill get a refund on it and continue to use my Motul at hopefully 5000km intervals.

For track days as suggested (I considered this previously) might shove some Chrono 800v in there for extra protection from the strains of circuit racing.

I have had an oil temp guage sitting in my room for a while but havn't got round to getting it in. Was qouted fairly lofty prices to get it installed because of all the labour involved. My mate suggested it would be cheaper to hook it up to the sensor on an oil cooler so might have to wait till then to get a temp readout on oil.


Btw why ive got your attention Im gunna ask what is probarly a common question your sick of around here.

If I do use the fully synthetic Chrono 800v am I likely to get oil leaks as it can tend to expose any little gaps previously held by sludge ect? I recently had my cam and crank seals replaced so they should be fine and since then I havnt had any leaks from using my semi-synth motul turbolite.

quote:
Originally posted by Titan:

Seems I've read that maximum efficiency occurs somewhere around 212 F....but, not sure maximum efficiency is what you are looking for. With regard to oil temp, remember, it depends upon where you are measuring the temperature!

Click to expand...
I find this interesting because I have read to that hotter engine temps can increse effeciency and lower oil/engine temps can increase power. However lower oil temp means thickening of the oil possibly which goes against theories of thicker oil while providing thicker films takes more to pump ect --> less power while suggesting the thinner oils are what are more effecient and power gaining!

Also what is the ideal place to fix a oil temp sensor to for the most accurate readout. Weld in the sump pan? How would it go hooked up to an oil cooler sensor? -prob depends where oil cooler is located I guess.

[ May 25, 2006, 11:54 PM: Message edited by: Gards ]
 
Your coolant temp will determine your combustion efficiency ...I would think. I don't think it's an issue in circuit racing where total cooling and power output kinda trump "efficiency".

Oil temp is a variable in an otherwise adaquately cooled engine. It's merely a matter of "indexing" your target viscosity with your max oil temp. If you're routinely above 120C then you need to figure out what the adjusted visc is. 100C is just what it's spec'd at. A 50 weight is a 40 weight is a 30 weight is a 20 weight at different temps above 100C ..and so on if you reverse it. What weight do you want to run? What temp keeps it where you want it? It's not always practical ..but I think you see what I'm getting at. Overly cooled oil (of any ultimate resultant weight) is typically shunting btus that would be soaked up and rejected in the coolant, or sent out the crapper in the exhaust.


Synth will not leak any more or less then a dino. Some agents that some synth are composed of allegedly swell seals that may cause leaks. Otherwise ..a leak is a leak.
 
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