Cold start wear vs. hi/low viscosity

[LarryL]

We stopped UOA's years ago. On some engines we have weighed and measured parts before rebuilding an engine and done the same after final tear down. I remember that we tried to figure out UOA's and apply them to design and maintenance but too many times one or more values would spike or drop. Experts looked at the stuff but we relied on tear downs to find out how the engines were doing. We do pay attention to TBN but, really, the maintenance schedules are pretty consertive and fixed. We don't look to any analitical information to tell us much. Actually the engine packages are easy to work on and if we need to pull an oil pan and look at the bearings, we do just that. What I wanted to say was that different viscosities of oils haven't showed us much and we are not going to anything lighter than 0w-30 any time soon. and we do use a lot of 10w-40 and it works just the same as far as we can tell for our application.

I have talked to our customer and late this summer we will put one engine on 5w-30 dyno oil and do all that measurement stuff and some UOA's and publish the numbers, if anyone is interested. We can compare this with a 5w-30 synthetic oil. I just have to talk, some more to our customer. He's not into analysis, just performance so we'll see what happens, as long as everyone takes the numbers for nothing more than an isolated case of non-auto engine operation.

 

[oilyriser]

If the UOA's on 15w40 tend to be better than 0w30, it might be due to the climates where the two grades tend to be used. 0w30 tends to be used in very cold areas, where cold starts involve a lot of moisture and fuel condensing on cylinder walls.

 

[AEHaas]

The temperature thing is important. If you ran the 15W-40 in Canada for a year and the 0W-30 in Texas you may find that the thick stuff gives a terrible UOA whereas the thin stuff in Texas gives the best UOA. This certainly goes along with my 0W-20 results in the Ferrari.

aehaas

 

[TallPaul]

quote:

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Originally posted by Gary Allan:

quote:

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Therefore, the cold gen-set engine probably sees less overall cold operation wear for the same amount of cold operation than an automobile does (excluding the 1970s mindset of 5 minute driveway warmups).

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I dunno

I reason that it would have much more wear per hour than an automotive application due to the full load in the warm up state.

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Good point. The automobile is generally driven with a lighter touch until somewhat warmed up. Still the changes in load and operating speed may have a substantial effect. Also, would need to know what full load is on the stationary engine, as they should not be running at full capacity, but some fraction of it I would guess.

 

[Rev440]

A) You said that thin oils obtain pressure quicker?..........what?????? The pressure is always higher at any RPM when the oil is thicker and that is why the bypass valve opens with thick oil...cause the pressure is too high.

I took MGBV8 statement as pressure on the gage would show quicker and for academic discussion, "neglecting the running pressure".
...Being; Thinner oil will be pumped quicker to the first oriface after the pressure gage. If the oil hits the oriface quicker, the gage will show a reading in less time than a thick oil.
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B) And then you said the RPM drops with thicker oil???????????WHAT????????? When you start our cold motor, it goes from 0 rpm to idle speed and hits every RPM in the middle on the way up. Most engine computers set the cold idle at higher RPM. Basically, your right foot controls the RPM when your on it and your computer controls it when you are idling.......what on God's green earth ar eyou talking about here?

Prior to BITOG, my Edelbrock carb'd 330 hp GM engine would idle at 700 +- 50 rpms with 15w40 rotella. After digesting some BITOG I promptly went out and changed to 0w30 M1. The engine off start idles between 850~900 rpms. Monitoring the performance at start up after several cold weekends, I found I could turn the idle down a bit. I am always impressed at the cranking speed upon startup.

 

[Ugly3]

quote:

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Originally posted by LarryL:
We stopped UOA's years ago. On some engines we have weighed and measured parts before rebuilding an engine and done the same after final tear down. I remember that we tried to figure out UOA's and apply them to design and maintenance but too many times one or more values would spike or drop. Experts looked at the stuff but we relied on tear downs to find out how the engines were doing. We do pay attention to TBN but, really, the maintenance schedules are pretty consertive and fixed. We don't look to any analitical information to tell us much. Actually the engine packages are easy to work on and if we need to pull an oil pan and look at the bearings, we do just that. What I wanted to say was that different viscosities of oils haven't showed us much and we are not going to anything lighter than 0w-30 any time soon. and we do use a lot of 10w-40 and it works just the same as far as we can tell for our application.

I have talked to our customer and late this summer we will put one engine on 5w-30 dyno oil and do all that measurement stuff and some UOA's and publish the numbers, if anyone is interested. We can compare this with a 5w-30 synthetic oil. I just have to talk, some more to our customer. He's not into analysis, just performance so we'll see what happens, as long as everyone takes the numbers for nothing more than an isolated case of non-auto engine operation.

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What type of engines are you talking about here?

 

[MGBV8]

Rev 440

Yes, observations from driving old cars.

M1 description of 0W from information to Scooby owners.

ulta quick circulation offered by the 0W rated product.

I assume quick circulation not only provides oil film but also puts in place the aw additives.

The drainback issue is interesting as 0W oils should drainback quicker and warm up slower. Esters should remain on surface and I believe Molakule mentioned that the GC PAO derived ester was as polar as mineral, so perhaps a mineral or semi has an advantage re drainback unless compared to an ester based oil?

Fast engine warm up and avoiding thermal shocks may be more important than oil choice.


information from Mobil re Scoobies.

Mobil 1 0W-40
Subaru Japan have stated that all oils with a 0W rating will invalidate engine warranty. This is because 0W viscosity has not been tested by Fuji Heavy Industries and is unlikely to be tested by them in the near future. It is not a result of engine problems and is not related to synthetic technology or oil quality. This oil which operates at temperatures as low as minus 54 degrees exceeds the quality level required of Subaru vehicles. This oil was used by customers for 2 years in Subaru engines without any claims for engine failure before the Warranty Bulletin was produced regarding OW oils.
Mobil recommend Mobil 1 0W-40 for vehicles outside warranty.


Mobil 1 15W-50

Mobil 1 Motorsport 15W-50 uses the same synthetic technology which results in fast flow rates and reduced friction. It is designed for ardous race and rally use at the highest temperatures where a thicker more stable oil is required. Again this lubricant has not been tested by Fuji Heavy Industries so they cannot give approval.
Mobil recommend 15W-50 for use outside of the warranty.


Mobil 1 5W-40

Using the same technology as Mobil 1 0W-40, MOBIL HAS MADE MOBIL 1 5W-40 EXCLUSIVELY AVAILABLE TO SUBARU DEALERS.
This product fulfils the viscosity requirements of Subaru for use in all of their model range. Mobil 1 5W-40 makes available the same benefits achieved by Mobil 1 without the extreme low temperature capability and ulta quick circulation offered by the 0W rated product. Mobil 1 5W-40 will be available exclusively to Subaru dealers for routine servicing. For interim lubricant top-up, we advise customers to either return to dealer for top-up or use Mobil 1 Motorsport 15W-50 for DIY top-up. While Motorosport is 15W-50m, the viscosity will have negligible effect on the sump viscosity and the lubricants are totally compatible.


Semi-synthetics 10W-40

Mobil Super S 10W-40 and Duchams QXR 10W-40 have been accepted for use during the warranty period and whilst not delivering the optimum performance of fully synthetic engine oil, they still exceed the performance requirements necessary to meet the Subaru warranty.


Summary

During the warranty period and in order to adhere to the viscosity requirements of the Subaru warranty, Mobil recommend the use of Mobil 1 5W-40, Mobil Super S 10W-40 or Duckhams QXR 10W-40. Out of warranty, Mobil recommend Mobil 1 OW-40 or Mobil 1 Motorsport 15W-50"

 

[1sttruck]

Another consideration in favor of HDEOs is that one could use a 15w40 in a number of vehicles that normally use a PCMO, and a 10w30 dino HDEO in most, but few of the PCMOs, dino or synthetic, would fare well in a diesel calling for a current spec like CI-4. A 5w40 synthetic HDEO will do very well in hard use vehicles that would normally use a PCMO, and a 0w30 synthetic HDEO will do well in almost all. It suggests that the additive pac in the HDEO might provide protection similar to a PCMO synthetic where a PCMO is used. I'll guess that HDEOs do well in cold start situations due to the large amounts of anti-wear additives.

 

[Stinky Peterson]

I don't know if this is a good place to post this but I though since we are talking about low temp and viscosity it might be appropriate. This also does a good job of showing the "cold soak" phenomena.

This slide shows different commonly used oils that were cold soaked for 16 hours at -35°C (-31°F).

In ten seconds only the amounts of oil shown flowed out of the beakers. Flowability is poor for all except the 0W-30 and synthetic lubricants.

If the oil is cold soaked for 48 hours at -35°C (- 31°F), the flowability is much worse.

Longer exposure to cold allows more wax crystals to form in petroleum base oils, but the synthetic base oil is virtually unaffected by the longer cold soak because synthetic oil contains no wax.

 

[Drew99GT]

Yup, better be running that 5w-20 on the surface of the sun or your risking cold start wear

Thanks Stinky. The difference between 5w-20 and 10w-30 is indestinguishable. It looks like the 10w-30 is more molasses like, but the same amount of oil flowed for each

 

[Steve S]

Notice the syn. oils are great for cold . Maybe by looking at the cold oil the people who think they know about cold start wear will understand what cold start wear means. Stinky would you know what groups the petro oils are?.

[ April 27, 2005, 09:55 PM: Message edited by: Steve S ]

 

[Steve S]

Could the moderators put Stinkys cold soak post on the home page for future reference .Also this would be good for every one to see.

 

[Drew99GT]

This doesn't exactly simulate pumping or cranking. Don't go out starting your car at -20 with 10w-30!

 

[Ugly3]

I look at Stinky's oil flow pics and I wonder what I did to my old car. I had a 1956 Mercury and ran straight 40W oil all year around. One winter (must have been in the mid 1960's) we had 2 days back to back of -20F temps at night. I brought the battery in the house at night and kept in on a charger (the battery was a really good one, it cost $12 new). Anyway, the car started both days but it was a chore. Probably added 5000 miles of wear those two days.

 

[TallPaul]

quote:

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Originally posted by Ugly3:
Probably added 5000 miles of wear those two days.

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And still the body probably rusted out long before the engine would have worn out.

 

[Stinky Peterson]

I don't know anything about the oils used in the picture. I'm a bit puzzled by the terms 0W30 and Syn Oil as I've not seen any 0W30 that are not synthetic. The cold soak time did surprise me as I've heard people talk about vehicles being harder to start the longer they were exposed to low temps. I hadn't thought about crystal growth occurring over time as my experience with crystals has been in aqueous solutions where it happens quite fast. DanG viscosity has tripped me up more than once!

I'm just thankful we have positive displacement pumps that pump the same amount of oil per revolution (regardless of viscosity) otherwise we couldn't use the 15W40 when it gets to -40 like it does around here.

 

[Ugly3]

quote:

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Originally posted by TallPaul:

quote:

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Originally posted by Ugly3:
Probably added 5000 miles of wear those two days.

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And still the body probably rusted out long before the engine would have worn out.

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Actually, you are right. The body was "bondo'ed" in the following year or two and the car was sold with 110,000 miles on it.

 

[TallPaul]

quote:

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Originally posted by Stinky Peterson:
I'm just thankful we have positive displacement pumps that pump the same amount of oil per revolution (regardless of viscosity) otherwise we couldn't use the 15W40 when it gets to -40 like it does around here.

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0wXX and 5wXX are for sissies! Real men run 15w40 year round.

 

[MGBV8]

Andy

Warranty wise its best to use oils recommended and may be worth checking with SoA.

Latest UK information I have (the quote was from 2000, so may be out of date) Impreza 2.0i WRX/STi Turbo 2001 onwards

Motul technical dept 5w-30 or 5w-40
Silkolene technical dept 5w-40
OATS database 5w-30 or 5w-40

 

[Steve S]

0wXX and 5wXX are for sissies! Real men run 15w40 year round.

[/QB][/QUOTE]
Synthetic 15w/40.