What are the mechanics behind start up wear?

[Velo_Fello]

AFAIK, Grp I & Grp II oils stick well to engine internals; Grps III & IV do not. Grp V esters stick excellently well to engine internals, in my direct personal experience.

Hence, cold starts on Grps III & IV could lead to some engine internals e.g. pistons, rings, wrist pins, going unlubricated for some time.

These days, cold starts with synthetic oils containing esters seem to be the least harmful. There's always a film of oil there until splash gets there.

As an example, I have a Dodge Caravan 3.3 ltr with a shot crank. Starting it up cold on bulk 5-30 produces an atrocious anvil chorus. This goes away with ester based motorcycle oil or Royal Purple, which I understand has around 15% esters. This won't please the Grp V haters on this site, but there it is.

 

[fsskier]

Originally Posted By: SteveSRT8

I own American made V8's with pressure fed oil all the way to the wrist pins. In no way is the cylinder wall dry for more than a second or two. I have yet to see any modern engine in our shop that did not feed oil all the way up through the rod.


If you carefully examine the oil path that you describe you will find that the flow to the cylinder walls will be very poor with cold thick oil...... The flow is through the drilled crankshaft, with only marginal connections through both the main and rod bearing shells, then somehow through your apparently hollow connecting rods, to the piston pins... which do not contact the thrust faces of the piston....

Anyway, your argument is with a multimillion dollar GM research paper, not with me.

 

[SteveSRT8]

^^^A very old one as well!

 

[SteveSRT8]

C'mon, guys, does anyone here really believe a modern reciprocating car engine is splash lubed?

 

[friendly_jacek]

Yap, people are barking wrong tree here.
Studies actually showed the start up wear is indeed mostly located in rings and liners, but is mostly chemical in nature. The colder and more sulfur in fuel, more wear detected by Cr isotope tracer. And thus more failures in northern engines would be expected.

 

[expat]

Cyl wash from over rich A/F ratio on a cold start is also a factor.

But as I said, there are many.


Yes modern engines DO rely on Splash to some degree, after all, All the oil fed to the crank gets thrown off somewhere!

Most con rods are drilled, but many get oil to thr small end via a depression and hole at the top end (a designe I like, as the oil enters the un-loaded side, via splash, on the up stroke. Also, rod strength/weight is not compromised)

 

[aquariuscsm]

Castrol needs to bring back that "Startup" oil :^P

 

[Shannow]

Originally Posted By: SteveSRT8
C'mon, guys, does anyone here really believe a modern reciprocating car engine is splash lubed?


You are purposely using outdated nomenclature to make a case.

Splash lube is troughs of oil that "dippers" on the bottom of connecting rods dip into to provide mixed lubrication of bearings, and "splash" of other surfaces.

The mechanism of cylinder lubrication relies on oil flying around, which, is understandably lacking early on in the operational cycle.

You don't seriously believe that engines have pressure lubricated piston faces...so how does the oil get there ?

 

[Shannow]

Originally Posted By: aquariuscsm
Castrol needs to bring back that "Startup" oil :^P


They haven't dropped it down here.

There's umpteen different "Magnatec" oils.

 

[Zaedock]

I've always felt it has more to do with cold engine/components than cold oil. Several of my SAE30/10W40 UOA's in my trail Jeep had single digit Fe numbers in a design known to shed. Seasonal trail time consists of starting, heading to the first obstacle, shutting down for the guy in front of you, starting up - driving the obstacle, shutting down to wait for the next guy, so on and so forth - all season and a few snow runs. The Jeep is also tailered to the tails.

The oil temp definitely never reaches operating temp. The block remains warm throughout the day. The only difference I would offer in this case compared to a stock Jeep, would be that I run a high volume oil pump (IMO, Jeep valvetrain lubrication is lacking).

 

[Corvette Owner]

Here's a 2009 post of how cylinder walls are lubricated:

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1629295&page=1

 

[expat]

I have often wondered about making a device ,that could inject a small amount of upper cyl lube into the fuel rail, when the ignition is turned on prior to a cold start??

 

[Zaedock]

Originally Posted By: expat
I have often wondered about making a device ,that could inject a small amount of upper cyl lube into the fuel rail, when the ignition is turned on prior to a cold start??


To keep the mosquitoes away?

A system like that is not needed. Engines have the potential to go hundreds of thousands of miles. More often than not, the vehicle's body rots before the engine dies.

 

[mechtech2]

Originally Posted By: SteveSRT8
C'mon, guys, does anyone here really believe a modern reciprocating car engine is splash lubed?


Yes, I do. And that is because many parts ARE splash lubed/incidentally lubed.

[I realize that Chevy is putting oil pumps on cars since the early 50s. They are no longer fully splash lubed.]

 

[mechtech2]

Originally Posted By: SteveSRT8
Splash lube cylinder walls? I thought we were talking about car engines! What century are we talking about?

I own American made V8's with pressure fed oil all the way to the wrist pins. In no way is the cylinder wall dry for more than a second or two. I have yet to see any modern engine in our shop that did not feed oil all the way up through the rod.

And CorvetteOwner, my car is naturally aspirated and uses oil squirters aimed directly at the piston crowns from underneath. I'm pretty sure it's a bit over lubricated!


Oil through the rods to the pins was really rare, and still is not as common as holes in the piston to lube the pins. Most rods are not drilled. Useless on a pressed pin, anyways.