Start up protection differences - 10w, 15w, 20w?

[Shannow]

Originally Posted By: CT8
The starting viscosity is most important when considering how long the time it takes to travel from the sump to the oil pump.


Pretty close, and way closer than those who say it's to do with pumped oil flow.

Per the ASTM...

Quote:
The low-temperature cranking viscosity is measured according to the procedure described in ASTM D5293 and is reported
in milliPascal·seconds (centipoise). Viscosities measured by this method have been found to correlate with the ability of
engines to start at low temperature.

The pumping viscosity is a measure of an oil's ability to flow to the engine oil pump and provide adequate oil pressure
during the initial stages of operation.
.
.
.
Because engine pumping, cranking, and starting are all important at low temperatures, the selection of an oil for winter
operation should consider both the viscosity required for successful oil flow, as well as that for cranking and starting, at the
lowest ambient temperature expected.

 

[rokwldr]

I have never seen a blown engine blamed on start up wear. If you use good quality oil there will be no problems. !0-30 M1 in my GMC Canyon now but soon to use M1 10-40 HM.

 

[Garak]

In Florida, I should hope not. But, it is quite possible up here to have a very poor oil choice at the wrong time of year and wreck an engine in short order due to careless operation. One has to try some mighty stupid stuff, but hey, stupid stuff is tried all the time.

 

[Clevy]

Originally Posted By: Stelth
Hmmm... I'm no engineer, therefore I offer this anecdote (rather than a double-blind, peer-reviewed study). In my old 2001 GMC Savana, the oil pump appears to bypass at around 60-65 psig on the factory gauge. I say that because, regardless of speed or temperature, the gauge will rarely go higher than that.

When started cold, California cold that is, regardless of the oil viscosity rating, the gauge goes up to around 65 psig. It remains there when driving off. Therefore, I conclude that the pump is bypassing, since engine rpm is increasing, and oil pressure isn't. After it warms up, idle pressure is about 25 psig, increasing to 65 psig at cruising speeds.

This van specs 5w-30, and has a 4.3 V-6. I generally have used 5w-30 or 10w-30.

I tried 20w-50 once as an experiment to see if it would slow oil consumption. It didn't. However, at a cold start, the oil gauge would reach 65-70 psig, and remain there when driving off. My conclusion, of course, was that the pump was bypassing, since oil pressure didn't increase with rpm.

My final conclusion was this: the lighter oil didn't pump faster since we're talking about a positive displacement pump, but it did move faster through the system, because at the same pressure (pressure set by pump regulator bypass), a thicker fluid will flow more slowly through the same restriction.


Well said.


Beers

 

[rokwldr]

Stupid, realy. I guess in Canada you could use oilve oil and do OK. I was speaking of S.Fla. I used M1 15-50 in a 2.8 S10 that went 250,000 miles. That says a lot to me. Just saying.

 

[expat]

Did't those 2.8's have crank problems?

Question: Does the oil supply pressure matter, as long as all parts of the engine have an adequate supply. Bearings presented with oil will take what they need. You can't get more in, regardless of pressure)

How unclean is oil that by-passes the oil filter (surely it's already been through the filter many many times)

 

[Clevy]

Originally Posted By: rokwldr
Stupid, realy. I guess in Canada you could use oilve oil and do OK. I was speaking of S.Fla. I used M1 15-50 in a 2.8 S10 that went 250,000 miles. That says a lot to me. Just saying.



Really.
Considering that engine calls for a 30 grade unless oil temps are way higher than normal there's really no gain going to a 50 grade.
You've basically increased pressure forcing more bypass events and if the pump bypassed you've effectively lowered oil volume being pumped.
Ambient temps don't mean a whole lot in a thermostatically controlled engine.
What funny is you believe you've achieved something unheard of. I've seen 2.8l engines in old camaros with 300000kms using 5w-30. They ran great at that mileage.
So even though it says something to you in real life that's not a milestone nor is it impossible.
In an s-10 the engine is barely worked. The truck itself is light so the engine is under light load.
Just sayin


And before you get your butthurt re-read what Garak said. He wasn't calling you stupid.

 

[Clevy]

Originally Posted By: rokwldr
I have never seen a blown engine blamed on start up wear. If you use good quality oil there will be no problems. !0-30 M1 in my GMC Canyon now but soon to use M1 10-40 HM.



If you aren't leaking oil why a high mileage flavour? If there is some consumption I suggest m1 euro 0w-40. The more I use this stuff the more I like it. Once my stash is burned up I think I'll be stocking a single oil and presently it's a toss up between elite 222 0w-30 and euro 0w-40.
If you've got gasket leaks I highly recommend liqui-moly motor oil saver. If the gasket isn't damaged thus stuff with stop your leak.

 

[Doug Hillary]

Hi,

Here's another "two bobs" worth;

There are many theories on this subject and many practical realities too. As Shannow has pointed out the real differences appear as intended at the lowest extremes of temperature

However, in the warm up phase from a cold start to a stabilised (coolant/lubricant) operating temperature a lot depends on the engine design and application – and the lubricant.

It depends on how it is operated from a cold start – most people use high revs and loading in the warm up phase and others are more “empathetic”. These factors need to be accommodated at design level to ensure driveability, durability and longevity – as well as to encompass exhaust emission regulations which have been a factor for several decades as we know and are still at excessive levels in places like Shanghai etc. The lubricant plays a vital role in this matrix!

In the 1960s for instance Daimler-Benz had a sophisticated lubricant Approval’s programme and List and did all of their lubrication system’s maintenance tests using a SAE10 lubricant!

Lubricants in IC engines must circulate to lubricate, however in modern engines they must also for instance operate as the hydraulic actuator of valve control mechanisms (one example) – this is a pressure factor which needs to be consistent. Flow rates become more important too as the circulating lubricant’s loss rate increases via the proliferation of various ancillary components, squirters (some temperature/revs sensitive) etc. – and the flow needs to be consistent. Technologies are rapidly changing the game; some engines for instance now have controlled lubricant flow matched to the engine along with ECM control of the cooling system thermostat!
All this along with cooling system integrated oil coolers/warmers in some engines designed to speed oil warm up optimise the designed viscosity requirements thereby reducing frictional losses. Base oils play a significant role in the mix too of course and the lubricant is optimally kept in a narrow operating temperature band

Lubricant issues do occur – have done in the past and will in the future. Mack, Cummins and many other OEMS that sell vehicles into very diverse markets can attest to this! Just consult Japanese Vehicle Operators Handbooks for the diversity available in some situations. As an aside, mechanical failures have occurred in the distant past for instance, with the use of a 20W-50 viscosity lubricant when it was specified in an engine originally was using 20W-20 or 20W-30 viscosity lubricants – the “A” Series BMC Mini engine being but one example. An oil system redesign was the fix!

Other more recent situations have occurred too with serious engine issues occurring in Europe recently in Artic type winter conditions, used lubricant “gelling” was the defined reason. Daimler AG have spent time on this and no doubt included the needs in their most recent listed specifications (likely to end up in ACEA specifications too)

In my own experience in repeated testing over a 30mins warm up cycle (over 50 cycles) the operating “feel” of a Porsche DOHC 32V V8 on three different lubricants; a mineral 20W-50 and 15W-50, 5W-40 synthetics there was definitely a more responsive feeling with the 5W lubricant. The commencing/ending ambient temperature varied around 12C. The actual warm up time to stabilisation was about the same but “driveability” was significantly improved with the 5W lubricant – somewhat confirmed by the OP gauge readings at various stages. This engine is equipped with a thermostatically controlled air/oil cooler, 8ltr oil capacity and a designed stabilised operating temperature of 85-90C

This situation was similar in heavy high speed diesels when changing from 15W-40 (mineral & semi-synthetic) to a synthetic 5W-40. The OP gauges confirmed this at various stages. Even “un-practiced” professional Drivers could tell the difference when starting and operating cold soaked engines from around 0C>

IMO the freer flowing 0W & 5W lubricants spend less time transiting the oil pump and filter’s differential by-passes in the warm up phase than those with a higher rating

This is but one reason why Engineers in charge of looking after expensive Classic vehicles such as in the Porsche Museum in Zuffenhausen typically warm 20W-50 lubricants to 80C before applying revs or load!

Mr Average Driver simply couldn’t care less – so the OEM must cater for the intended application’s most common situation, likely to be the worst one in our opinion!

 

[Garak]

Originally Posted By: rokwldr
Stupid, realy. I guess in Canada you could use oilve oil and do OK. I was speaking of S.Fla.

As I noted, there aren't major startup wear issues in Florida, but people live all over, people move, and some people live in variable climates. There are cases of people having licorice-sticked their distributor shafts in Canada thanks to silly oil choices. In the carb days, it was deceptively easy to start an engine in -40 despite the fact that it had something atrocious in the sump like a 20w-50 or a monograde, and there were people shedding tears over that.

I try to run something year round that isn't going to give me grief in January. I don't worry about startup wear in July whatsoever, but I'm not switching to a monograde just because I have no fear about startup wear in summer.

 

[Garak]

Originally Posted By: Doug Hillary
Mr Average Driver simply couldn’t care less – so the OEM must cater for the intended application’s most common situation, likely to be the worst one in our opinion!

Thanks for that very informative post, Doug!

 

[Capa]

Thank you Doug, Stelth, and Turtlevette---very informative!

 

[expat]

This is but one reason why Engineers in charge of looking after expensive Classic vehicles such as in the Porsche Museum in Zuffenhausen typically warm 20W-50 lubricants to 80C before applying revs or load!



[/quote]


Why would they not use a 5w-50?

 

[Shannow]

Originally Posted By: Shannow
Originally Posted By: CT8
The starting viscosity is most important when considering how long the time it takes to travel from the sump to the oil pump.


Pretty close, and way closer than those who say it's to do with pumped oil flow.

Per the ASTM...

Quote:
The low-temperature cranking viscosity is measured according to the procedure described in ASTM D5293 and is reported
in milliPascal·seconds (centipoise). Viscosities measured by this method have been found to correlate with the ability of
engines to start at low temperature.

The pumping viscosity is a measure of an oil's ability to flow to the engine oil pump and provide adequate oil pressure
during the initial stages of operation.
.
.
.
Because engine pumping, cranking, and starting are all important at low temperatures, the selection of an oil for winter
operation should consider both the viscosity required for successful oil flow, as well as that for cranking and starting, at the
lowest ambient temperature expected.


Supportive of the above quotes, and my statements re pumping/protection, are the results from some cold weather multigrade testing.

Columns to the right are time taken to see rocker arm flow, and the time to full oil pressure.

SAE30 at freezing, took 3 seconds to have flow out of the rocker arms, and 6 seconds to full oil pressure.
at 20F, still 6 seconds for full oil pressure, 15 for rocker arm flow.

The 5W20 at 12F produced rocker arm flow in 5 seconds, and 6 to full oil pressure...

The 5 and 3 for rocker arm flow are all but the same, and there's no way that at 30F the 5W20 is going to outflow the SAE30, as I say, it's a Positive Displacement Pump, espacially in the gallery filling phase.

Drop the temperatures some.
SAE30 at 20F, 10W30 at 9F, and 5W20 at -11F all offer about the same levels of "start-up protection". As per the ASTM quote, pick a viscosity suitable for you ambient.

SAE30 would be OK in my environment, which has probably only seen three 20F mornings in two decades...in the oft quoted Floridan context, the 5W would offer noting in terms of protection over either the SAE30, or the 10W30 that those debates usually pertain to.

(As an aside, I use 5W, 5W30 A3/B4 is my favourite ATM, with less VII than the more popular 40s, and still an HTHS over 3.5).

As the the other part of the quote, "cranking and starting", I've never pulled apart a dry engine, there is always copious oil in the bearings, and pistons/rings.

This is thick, and at the extremes of temperatures, can have the term "breakaway torque" applied to it - my old physics teacher from Calgary described a beetle, SAE30, and a hill as the only way to overcome breakaway torque in his youth.

OVERKILL has mentioned many times "ease on the battery" with the lower "W"s

Same engine as the above tests, this time cranking speed and startability (diesel engine). Diesels need speed to get the compression temperatures high enough for ignition.

The lower "W" grades, as expected give better cranking speeds at colder temperatures....above freezing, VI probably comes into it.

 

[tig1]

This video was posted some time ago, but I thought it shows very well the difference in oil flow through the engine with different wt oils at cold temps many here at BITOG experience. Yes, PD Pumps do pump oil at the same rate, but as you can see it certainly doesn't flow through the engine at the same rate.

https://www.youtube.com/watch?v=OWiQyR7PWII

 

[Shannow]

tig1, that video has been discussed many many times, and really while impressive, that video only shows the difference between an oil that's chosen appropriate for the test conditions (-35C) than being representative of the flow rates of different oils through the engines.

The 10W and 15W are grossly inappropriate oil choices for -35C...that's the video in a nutshell.

 

[tig1]

Originally Posted By: Shannow
tig1, that video has been discussed many many times, and really while impressive, that video only shows the difference between an oil that's chosen appropriate for the test conditions (-35C) than being representative of the flow rates of different oils through the engines.

The 10W and 15W are grossly inappropriate oil choices for -35C...that's the video in a nutshell.


As I said, this video was played some time ago, but clearly shows the flow rate of different wt oils. Warmer temps can not display the difference heavier wt oils flow through an engine. For our norther brothers where extreme cold starts can cause more engine wear because of slow oil flow, I thought they might find this interesting if they missed it before.

 

[aquariuscsm]

My take on this,is if it's that cold where oil will not flow whatsoever,sump warmers/block heaters make more sense imo than uber thin oil.

 

[tojo1968]

Originally Posted By: rokwldr
Stupid, realy. I guess in Canada you could use oilve oil and do OK. I was speaking of S.Fla. I used M1 15-50 in a 2.8 S10 that went 250,000 miles. That says a lot to me. Just saying.

I owned 2 vehicles with the 2.8 in them.
84 Firebird
88 S10
Both went well over 200k with the engines running like a top. Zero oil consumption. Used Castrol GTX 20w-50 and AC Delco filters(PF47and PF52)in both because I was young and "thicker was better". Firebird spent its life in Pensacola and the S10 lived between Pensacola and New Orleans.

 

[kschachn]

Originally Posted By: aquariuscsm
My take on this,is if it's that cold where oil will not flow whatsoever,sump warmers/block heaters make more sense imo than uber thin oil.


Which one of 10W, 15W or 20W is an uber thin oil?