Engine Start-Up Wear

[friendly_jacek]

Originally Posted By: edhackett
Quote:
So if it's not that oil flow is less right after start up, then what causes wear?


The largest contributor to wear when cold is the fact that the operating clearances are not to specification. Different metals expand at different rates. Until the engine is fully heat stabilized the clearances are off. The most striking example is pistons being oval. They are machined out of round so that as the various thicknesses of metal heat up the piston achieves a round shape. A cold piston can have clearances that are four to five times normal operating clearance on one axis.

Some anti-wear additives are not effective until the oil warms up.

Rich mixtures wash oil from cylinder walls. This is less of an issue with fuel injection, but is returning as a real problem with direct injected engines.

Ed


Good explanation. There is also effect of water condensing in cold cylinders mixing with combustion products (especially sulfur) and the resulting acid reacting with rings and also mixing with oil.

Most people don't understand that synthetic or thin oil is not always the best solution for startup wear. Some of it is probably due to synthetic oil marketing that is frequently misleading about benefits. I bet engine block heater will protect engine more than the 0W20 oil. Not that I'm against 0W20, I use it in my Prius (helps with MPG).

 

[aquariuscsm]

I think start-up wear is just a marketing ploy. I simply don`t buy it at all.

 

[d00df00d]

Originally Posted By: edhackett
The largest contributor to wear when cold is the fact that the operating clearances are not to specification.

Not what I heard.

I remember reading the results of a study that said that oil temp was the biggest contributor. They tested all combinations of hot or cold oil, and hot or cold engine. Oil temp made a big difference, engine temp made very little difference, and hot oil on a cold engine was better than a hot engine with cold oil.

If I find the link, I'll post it up....

 

[friendly_jacek]

Originally Posted By: d00df00d


If I find the link, I'll post it up....


Please do, I'm looking forward to the link. I want to learn something new.

 

[CATERHAM]

But is it hot oil or the fact that the hot oil has an optimum viscosity; i.e., a 5-30 with a 10cSt at 100C vs 150cSt at 20C or 500cSt at 0C?
A ultra light 0W-20 such as Castrol Edge with it's 20C vis of 82cSt and 0C vis of 215cSt would appear to have a clear advantage in this regard.
Many OEM's who specify high VI oils certainly see an advantage in having the lowest start-up viscosity possible.

 

[d00df00d]

Good point. I'm not sure that that question was answered.

 

[Steve S]

Originally Posted By: CATERHAM
But is it hot oil or the fact that the hot oil has an optimum viscosity; i.e., a 5-30 with a 10cSt at 100C vs 150cSt at 20C or 500cSt at 0C?
A ultra light 0W-20 such as Castrol Edge with it's 20C vis of 82cSt and 0C vis of 215cSt would appear to have a clear advantage in this regard.
Many OEM's who specify high VI oils certainly see an advantage in having the lowest start-up viscosity possible.
Well yeah because they do not want bubba using straight 40 wt in 0* weather . Usually a really thick oil isn't needed.

 

[Steve S]

Originally Posted By: d00df00d
Originally Posted By: edhackett
The largest contributor to wear when cold is the fact that the operating clearances are not to specification.

Not what I heard.

I remember reading the results of a study that said that oil temp was the biggest contributor. They tested all combinations of hot or cold oil, and hot or cold engine. Oil temp made a big difference, engine temp made very little difference, and hot oil on a cold engine was better than a hot engine with cold oil.

If I find the link, I'll post it up....
oil up to temps is important for the heat activated additives .

 

[Steve S]

Originally Posted By: aquariuscsm
I think start-up wear is just a marketing ploy. I simply don`t buy it at all.
To totally eliminate startup wear ,,,, A Bob Is the Oil Guy first is and keep it secret. If you want to totally eliminate startup wear never and I mean never start up you engine. Otherwise just drive your vehicle and enjoy it and do not worry. Too much worrying not enough enjoying.

 

[flatlandtacoma]

Originally Posted By: JOD
Originally Posted By: flatlandtacoma
Originally Posted By: HBCALI
So switching from 5W-20 in my 2001 Accord to 0W-20 could help avoid start-up wear?
It depends. If you are routinely starting your engine at 40 below zero with no block or pan heater, then yes. Otherwise, probably not.

I'm not sure I agree with this. If you're comparing oils among a product grouping, the 0W oil will generally be thinner/flow better at any ambient temperature, not just 40 below??
Yes but how much thinner? Maybe 10%? I'm just saying that 10% thinner viscosity at startup at normal temperatures isn't going to make a noticeable difference in my opinion. Can you tell the difference between starting your cold engine on a 28 degree morning vs. a 30 degree morning? There is probably more viscosity difference in the oil in your sump at those two temperatures vs. having a 5w20 or 0w20 at either temperature.

You have to get down to really cold temperatures before the 0w20 and 5w20 diverge significantly. Just my experience.

 

[CATERHAM]

Originally Posted By: Steve S
Originally Posted By: d00df00d

.

oil up to temps is important for the heat activated additives .

Yes, for ZDDP IIRC you need contact surface temp's of at least 80C for the plating action to take place. But once it has occurred you've got the protection at colder temp's.
I believe moly activates at lower temp's.

 

[flatlandtacoma]

Originally Posted By: CATERHAM
A ultra light 0W-20 such as Castrol Edge with it's 20C vis of 82cSt and 0C vis of 215cSt would appear to have a clear advantage in this regard.
BTW, where are these numbers from? Are they published, measured? I'd like to see more on this.

 

[tig1]

Originally Posted By: addyguy
A pre-luber/warmer will pump oil throught the engine and almost completly eliminate start-up wear.

Most won't want to go through the hassle of doing that....!
Originally Posted By: Chris142
I think that you could somehow pressurize the oil system before starting the engine. This would stop most if not all of the start up wear.


Fine idea, but that won't happen. Recently I wanted to see the cam lobes on both Duratechs, however the only lobe I could see was pointing down on both engines. Little oil was seen on the backside of the lobe, so I just bumped the starter to rotate the cam 1/2 turn. Just doing that brought a lot of oil onto the cam, enough so that I had to wipe off the oil to clearly see the lobe. Thinner oil vs thicker oil has to help with start up wear.

 

[CATERHAM]

Originally Posted By: flatlandtacoma
Originally Posted By: CATERHAM
A ultra light 0W-20 such as Castrol Edge with it's 20C vis of 82cSt and 0C vis of 215cSt would appear to have a clear advantage in this regard.
BTW, where are these numbers from? Are they published, measured? I'd like to see more on this.

Sorry, I should have mentioned the source. I used the Widman Viscosity Chart which is based on an oil's KV40 and KV100 spec's.

Regarding an ultra light 0W-20 and a typical 5w20 conventional, using the Edge example it will be 35% lighter at 20C and as much 50% lighter at 0C.

 

[Mitch Alsup]

Originally Posted By: HBCALI
Ok, so on the front page article of BITGO (oil 101), it states that "...90% of engine wear occures at initial start-up..." Fine, I can agree with that. But along with that, the author dosn't really tell us how to get around start-up wear. It seems it can only be mitigated, but never avoided.


If you have a block heater, keep the block at operating temperature, and start the car with warm oil, you can mitigate most of the startup wear.

 

[flatlandtacoma]

Originally Posted By: CATERHAM
Originally Posted By: flatlandtacoma
Originally Posted By: CATERHAM
A ultra light 0W-20 such as Castrol Edge with it's 20C vis of 82cSt and 0C vis of 215cSt would appear to have a clear advantage in this regard.
BTW, where are these numbers from? Are they published, measured? I'd like to see more on this.

Sorry, I should have mentioned the source. I used the Widman Viscosity Chart which is based on an oil's KV40 and KV100 spec's.

Regarding an ultra light 0W-20 and a typical 5w20 conventional, using the Edge example it will be 35% lighter at 20C and as much 50% lighter at 0C.
edit: Good Point, I was not considering Castrol Edge. Yes, comparing Castrol Edge with a VI of 220 to a conventional with a VI of 145, you could notice a difference!

In my comments above I was thinking along the lines of Mobil 1 or Pennzoil Platinum where the 5w20 VI is in the 160 range and the 0w20 VI is in the 170 range.

 

[Beagle2000]

I am going to start using my block heater every night from now on, summer and winter so its toast warm everytime!!!!!

 

[rshunter]

Originally Posted By: Beagle2000
I am going to start using my block heater every night from now on, summer and winter so its toast warm everytime!!!!!

Imagine the electric bill for that...

 

[ZZman]

Start up wear can be affected by:

1. Oil flow
2. Additives in the oil and their ability to cling to the engine parts
3. ZDDP only works well after it has heat and load applied to it.
4. Higher moly content could help until the ZDDP kicks in.

 

[JasonBraswell]

http://www.mobiloil.com/USA-English-LCW/carengineoils_product-comparison-chart.aspx

"Excellent Startup Protection" hmmmm?