VIIs & differences in 5w20, 5w30 & 10w30 oils

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286
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Phoenix-ish, Arizona
Curious newbie here, trying to understand if the different percentages of VIIs in 5w20, 5w30 and 10w30 oils affect the amount of wear protection and cleanliness an oil provides. Here's what I've gathered so far after LOTS of reading - please correct me where I'm wrong! 1) The more VIIs in an oil, the less actual oil in the formula. The lower the percentage of VIIs in an oil, the more actual oil is present. 2) Oils with a narrower spread between the cold start number and the hot number contain lower amounts of VIIs, while oils with a larger spread between the numbers contain more VIIs. So 5w20 and 10w30 oils contain less VIIs than 5w30. 3) VIIs thicken the oil but don't lubricate. It's the oil that provides the actual lubrication, so theoretically at least, the more oil the better. 4) VIIs eventually shear, causing 5w30 oils to thin down to a 20 weight. The shearing can leave residue in the engine. 5w20 and 10w30 oils are more shear-stable. 5) Thinner oils flow faster than thicker oils, providing better cooling. Thicker oils provide better film strength but take longer to warm up and don't flow as quickly at operating temp, which might cause higher temperatures? Given all of the above (or not, if I'm in error) here's my sitch and my questions: The Crown Vic's 4.6L modular engine was originally spec'd for 10w30, soon changed to 5w30 for better cold climate starting, but this got changed to 5w20 for CAFE standards. I've read that in other countries it's still spec'd for 5w30, even 10w30 in Saudi Arabia. I live in a desert where summer highs are above 110*F and winter lows average about 40*F. We occasionally have a few hours of light frost but I'm never out driving at that time of night. I put on about 9500 miles a year: about half a dozen short trips a week interspersed with two easy, 60-mile round trips that are mostly highway. No rush hours or stop-and-go traffic. The car has 119K miles on it. Before I bought it a few months ago it was a federal fleet car in NM, maintained on Motorcraft 5w20. It's current fill is Napa 5w20 synthetic blend and it's running very well, but I'm wondering if 5w30 or 10w30 would be better in this climate? If an Xw30 oil would be better, should I go with 5w30 or 10w30? I also want to make sure I burn off any water from the short trips. How much longer does a Xw30 oil take to get to full operating temp compared to a 5w20 oil? Thanks for your time. This is a great community. I'm learning so much!
 

SR5

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Down Under
How about a full synthetic 5W30, or to save some money a 10W30 semi-synthetic (or even a 10W30 full mineral). Your climate sounds much like mine, and those oils work fine in that climate with easy driving. I'm sure some people with more extensive knowledge of VIIs and Ford 4.6L engines can add some details.
 

Nick1994

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Phoenix, AZ
There's no issue with running a 5w20 or 0w20 in that car in the heat. Your car's engine temperature is regulated with a fan and a thermostat, it doesn't matter if you're in 130 degree heat or 30 degree cold. I would change once yearly with Mobil 1 0w20 AFE or EP.
 

shiny

Thread starter
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286
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Phoenix-ish, Arizona
That's good to know. The heat here is scary sometimes. I came across this post over at crownvic.net (hope it's not violating any rules at either forum to copy it here): "The reason for the 5w30 or the 5w20 motor oil is that the valve lash adjusters work using the oil pressure to maintain the pressure of the valve spring against the stops for the valves in your engine. Ford went to 5w20 to make sure that the lash adjusters did not get pushed out of their seats in the engine which would loosen the valve springs leading to all sorts of problems with your engine." So I guess 5w20 really is good for the 4.6L modular engine in that it helps oil get to the top quickly. Makes me wonder... would Ford have spec'd 5w20 way back when if 5w20 was formulated as good as it is today?
 
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3,498
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Cincinnati, OH
Any three of those grades will work in the 4.6L. That Engine is really easy on oil. since your in Arizona I would probably use a 30Wt personally, but a xw20 will certainly provide good protection. Run M1 0w30 year around and you'll be all set. Shear really isn't an issue on the modular ford, that engine has all rolling components and the timing chain really doesn't shear the oil much. 10k on any synthetic in that engine is very doable unless it is severely short tripped.
 
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Cincinnati, OH
Originally Posted By: shiny
That's good to know. The heat here is scary sometimes. I came across this post over at crownvic.net (hope it's not violating any rules at either forum to copy it here): "The reason for the 5w30 or the 5w20 motor oil is that the valve lash adjusters work using the oil pressure to maintain the pressure of the valve spring against the stops for the valves in your engine. Ford went to 5w20 to make sure that the lash adjusters did not get pushed out of their seats in the engine which would loosen the valve springs leading to all sorts of problems with your engine." So I guess 5w20 really is good for the 4.6L modular engine in that it helps oil get to the top quickly. Makes me wonder... would Ford have spec'd 5w20 way back when if 5w20 was formulated as good as it is today?
I've assembled a few of these engines and those lashers aren't going to come out of that seat at all. the cam holds the roller rocker down tight. A 30wt is thin enough to not cause an issue.
 
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1,769
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Laramie, WY
Originally Posted By: Nick1994
There's no issue with running a 5w20 or 0w20 in that car in the heat. Your car's engine temperature is regulated with a fan and a thermostat, it doesn't matter if you're in 130 degree heat or 30 degree cold. I would change once yearly with Mobil 1 0w20 AFE or EP.
that's coolant temperature, not oil temperature. oil temperature can and will vary depending on many factors and one of them would be the outside temperature.
 
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CT8

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Idaho
"The reason for the 5w30 or the 5w20 motor oil is that the valve lash adjusters work using the oil pressure to maintain the pressure of the valve spring against the stops for the valves in your engine. Ford went to 5w20 to make sure that the lash adjusters did not get pushed out of their seats in the engine which would loosen the valve springs leading to all sorts of problems with your engine." [/quote] I have a bridge in Brooklyn I would love to sell you.
 
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472
Location
Hampshire, UK
Regarding your original post... 1) Correct but a tad misleading. An oil might be blended up from say 10% DI additive, 10% LIQUID VII and 80% base oil. Typically the liquid VII that blenders use for convenient handling is made up of 10% SOLID VII and 90% base oil. Also the DI pack might typically contain 30% base oil. So the oil you made up actually contains 92% base oil, not 80%. Oils are mainly oil.. 2) Correct for a given set of base oils but more complicated otherwise. It also matters if the blenders blend to 'tight' or to 'slack' viscometric limits. Typically a full 'proper' synthetic 5W30 blended tight will contain less VII than a full mineral 5W20 blended slack. 3) I've heard this theory before but I'm not sure it's based in fact. When a VII molecule uncoils at high temperature it adsorbs a lot of base oil so all the metal in the engine will see is oil, so it does lubricate. 4a) Yes VIIs can and do shear under the influence of high temperature and mechanical force. However some of the industry tests are very severe and suggest that oils shear more than they do in actual service. The HTHS test is run at 150C. I'll bet a penny to a pinch of salt that the oil in my car has never, ever gone above 100C. Likewise, the Kurt Oban mechanical shear test pushes the oil through a diesel fuel injector. The force you impose on the oil far exceeds anything you will see in the oil pump, bearings, etc. 4b) Yes, VIIs tend to be bad for engine deposits (especially in diesel engines) but I wouldn't say this was because of deposits left by shearing. Shear stable VIIs are often worse on engine deposits than high SSI VIIs because you need more overall polymer to make the viscometric balance work. 5) I'd say largely incorrect. You car's oil pump is a volumetric pump. The speed that oil flows through your engine is essentially fixed by the speed of the pump, not by the viscosity of the oil. Oils, thick or thin, have to all intents and purposes the same Specific Heat value so they all cool the engine in the same way. All oils are good for a Vic in the desert...
 
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860
Location
SD - South Dakota
With regard to #5 and the pump being a volumetric pump. I would say that is correct but with a caveat: http://m.youtube.com/watch?v=6QPahVJJqFw&feature=youtu.be The stock pump has a known weakness in the backing plate for the pump, so going with a heavier oil could reduce flown to the engine because of the inherent internal leak with the pump body. Something to consider before going to extremes with oil viscosity. My summers are far less harsh than yours, bit I've found 5w30 makes for a much quieter engine.
 

SR5

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Down Under
Speaking of oil temps., in the thread "How Thin can it go?", Shannow posted some directly measured oil temperatures. Depending on outside temp., and driving conditions, the same engine showed a 40 degC temperature swing. http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3810182/1
Originally Posted By: Shannow
Have been playing, sticking a type K thermocouple down the dipstick tube in my supercharged V-6 after driving...so the T/c is right where the oil is draining down from the crank. Normal oil temperature after my 25km commute is 105-110C, but if I hold it in 2 for the last 10km, raising the revs from 1,800 to 4,000RPM, same road speed, and tractive load, I can pull 130-135C. (Same cooling system)
Originally Posted By: Shannow
0C this morning it only got to 95C...coldest I've ever seen it after the 25km trip.
 
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472
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Hampshire, UK
My 1.0 litre N/A 3 cylinder which never goes much above 2500 rpm vs Shannon's Supercharged V6 might go some way to explaining the difference in our respective oil temperatures! Regarding the other point you raised (How thin can it go?). I am prepared to accept that from the viewpoint of basic lubrication (bearing loss, cams wear etc) that the arguement has been made and won. However from the viewpoint of thinness, in so far as it impacts on oil volatility, oil consumption and 'over-the-top' deposit formation, I'm not even sure that that argument has even been considered yet, let alone won. There is an excellent SAE paper from 2004 by Ertan Yilmaz titled 'The Contribution Of Different Consumption Oil Sources To Total Oil Consumption In A Spark Ignition Engine'. I would put the link in but when you Google it, it comes up as a PDF file (free to download). It's an excellent read. The technical language in it a bit impenetrable but it's one of the very few studies that looks at the effect of higher volatility oils and higher operating temperatures on oil loss. Sadly it didn't look at how this additional oil loss impacted deposits but I'm sure that if they had if looked at it, it would have been horrible! In my opinion, if you want use thin mineral, drive slowly and live in England. If you want to drive fast and hot in the US, don't use thin mineral, use thick mineral or thin synthetic.
 
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65
Location
Ca
Originally Posted By: Nick1994
There's no issue with running a 5w20 or 0w20 in that car in the heat. Your car's engine temperature is regulated with a fan and a thermostat, it doesn't matter if you're in 130 degree heat or 30 degree cold. I would change once yearly with Mobil 1 0w20 AFE or EP.
Water temp is regulated, oil temp is not. Ambient temps affect oil temps more than water temps affect oil temps and load and rpm have the largest effect on oil temps. In a hot area like Phoenix, not only is a 5-30 or 10-30 ok, I recommend it. If 5-20 is ok in your engine in a cold climate, say Michigan, it stands to reason that a 5-30 has to be ok in your climate seeing how the 5-20 will be thicker at startup and at full operating temp in a cold climate vs a Phoenix climate on any given day. You could make the argument that a 0w40 on a 100F day will be about the same viscosity as a 5-20 on a 50F day or running at 230F vs 180F I live in a Phoenix-like climate and have run Redline 0-40 in my Acura that specs 5-20 for a while. From its first oil change around 4,000 miles it got RL 5-30. From 90k to its current 135k it's had 0-40 in it. i wouldn't think twice about a 5-30 or 10-30 in your climate. It's absolutely no thicker than a 5-20 in a slightly cooler area. Use the oil best suited for your environment and driving conditions, not this dumbed down one size fits all mentality as applied to 20wt oils. I would also have no problem recommending a 0-20, especially a high VI oil like Toyotas 0-20 if the conditions called for it. The whole reason I went to the 0-40 was a change in my conditions. The car usually sees starting temps of at least 69F year round with much of the year being 80F+ at startup. For a week of the year it's started up in ~17F weather. The 0-40 is about the same viscosity at 17F as the 5-30 so the 0-40 made more sense as the year round oil. Admittedly the 4.0 HTHSv is pushing it but at the 113,000 mile valve adjustment, the cam lobes almost looked as it there had never been contact with the followers. The machining is still visible even on the nose of the cam. The cylinders looked new with perfect cross hatching using a scope to view. I'm just going to leave it alone and keep doing what I'm doing unless I move to a cooker area. On the flip side I use a very thin ATF which works very well with the Honda 5at but that's a different thread. But yeah, a cheap 10-30 or a decent 5-30 will be great in a Phoenix climate in a car that calls for a 5-20 in all climates.
 
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472
Location
Hampshire, UK
In the immortal words of Monty Python (the 'Bruce's' sketch), Australia is 'Hot enough to boil a monkey's bum!'...hence the 105 - 110C oil temps... G'day Bruce..
 
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43,651
Location
'Stralia
Nah, it pulls those temperatures in freezing conditions too. As a lubricant traverses the bearings, the engine performs work on it, and raises it's temperature 10-20C, add another 10 for the big end. So if the sump temperature is 100C (say), that exiting the mains is 110-120C, and the big ends more like 130C. Not carrying away the heat of combustion, as some here posite, but getting hotter due to the work done on it. My V-6, at 100km/h will obviously require the same tractive power to the ground at 1,800RPM in "D" or 4,000RPM in "2"...the difference on RPM providing 25-30C increases in lubricant temperature in the dipstick location. My old Erith machines (RIP, sisters to Kingsnorth) used to take oil, ISO 32 at 45C supply temperature, and have that oil leave the bearings at 85-90C.
 
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472
Location
Hampshire, UK
Water temperatures are regulated, oil temperatures are not... That's what I'd always thought until I started reading BITOG. Read this recent post... http://www.bobistheoilguy.com/forums/ubb...er_#Post3750542 It seems some vehicles are now fitted with an integrated coolant/oil heat exchanger as standard fit. The clever thing about these things is that not only does the rapidly heated engine coolant warm up the oil from cold but the direction of heat flow reverses if the engine oil gets too hot (the coolant can't ever go much above 100C otherwise it would boil). So it also acts as an oil cooler. Very clever!
 
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472
Location
Hampshire, UK
Ha! Freezing conditions to the average Australian is 'having to put your T-shirt back on!'... On the whole I don't regret leaving the asylum that work became but it's at times like this that I wish I could go and grab some thermocouples and check out what my oil is doing...
 
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43,651
Location
'Stralia
Joe90_guy, mines a type K found with a $20 multimeter, marked it to the length of the empty/full mark on the dipstick, run the vehicle on my calibrated circuit (commute), and throw it down the dipstick hole. IR gun on the sump shows 15+C lower than the T/C. We don't wear T-Shirts every day...this from a few weeks ago.
 
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