Engine Warm-Up Discussion.

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Originally Posted By: JHZR2
Originally Posted By: fredfactory
High viscosity itself protects cold.


Assuming you get flow... Which isn't guaranteed using sufficiently heavy lubes in low temps. And that other issues, like hydraulic tensioning of the timing chain.


The ADBV on oil filters should keep the journal bearings wet for the next cold start. Oil is there and getting pumped quickly 'cause the galleries are full always from the pump to the bearings. (Not sure about the oil being all the way up the pickup tube though.)
Cast-Magnatec markets their oil based on its sticky and stays on the cam lobes waiting for the next start.

Hydraulic tensioning problems are something I noticed on an '04 Chrys 2.7L v6 a while back, the timing chain flopped around on startup, then settled down, so good point there.
 
Originally Posted By: Claud
I understood putting the engine under light load, ie driving gently, until it was properly warmed up was best practice.

Claud.
Yes.
 
Originally Posted By: fredfactory
Originally Posted By: Pontual

The AWs that are temperature related surfactants won't work at low temperatures, BUT, what about the solid lubricants, as MoS2 and graphite. The would shime in there reducing the wear at warm up.


Nobody uses graphite anymore AFAIK. ArcoGraphite bit the dust in the 1980's. Ceratec might help.


Never heard of Krex though.
 
There are some GM that have delayed shifts when cold, this is to warm the converter and O2 sensor. A lazy O2 sensor will keep in this mode longer. AFAIK, they do shift, just at a higher RPM. Could this be the case?

Automakers used to test engines in the cold, by a cold start, 30 seconds warm up, then WOT until fully warmed up. The engines needed to survive without excess wear. Hopefully they still do some form of cold weather testing.

Rod
 
Originally Posted By: Shannow
I don't have any experience at -10C for more than a single day or so however.

Very nice post, Shannow. Well, you could have visited Canada this winter. Both Ontario and Saskatchewan had plenty of days below -30C, so you might have enjoyed that.
wink.gif
 
Originally Posted By: fredfactory
The trick is to find AW additives which don't need high pressure and high temperature to work.

ZDDP works well at high temperatures. High viscosity itself protects cold. That middle region is served by moly, poly-esters, boron, etc.


Had a dinner one evening and was sitting with/talking to an ex Castrol chemist who worked on the Magnatec lubricants in Australia....that's their whole reason for being, the mid warm-up.
 
Interesting.

How would this model relate to (a) The old "90% of engine wear in the first 30 seconds" mantra (which I've never seen a source for), and (b) the thin v. thick oil "debate", assuming it is possible to relate it to them.

For (b) it seems (to me) that if the oil had got there ( Since (a) is generally explained in terms of an initial lack of oil) thicker oil would tend to maintain hydrodynamic lubrication of the valve train better during warm-up, and it might locally warm up quicker too, because of greater internal shear-friction(?) and lower flow rates removing less local heat. This might activate the AW additives sooner.

Does this interpretation make sense?
 
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Originally Posted By: Ducked
Interesting.

How would this model relate to (a) The old "90% of engine wear in the first 30 seconds" mantra (which I've never seen a source for), and (b) the thin v. thick oil "debate", assuming it is possible to relate it to them.

For (b) it seems (to me) that if the oil had got there ( Since (a) is generally explained in terms of an initial lack of oil) thicker oil would tend to maintain hydrodynamic lubrication of the valve train better during warm-up, and it might locally warm up quicker too, because of greater internal shear-friction(?) and lower flow rates removing less local heat. This might activate the AW additives sooner.

Does this interpretation make sense?


Repeated the calcs with two other oils, note that these are comparisons against the original

Stribeck%20Shannow.jpg


TGMO...At 100C operating temperature would move everything to the left some.
100C
* bearings moves to 6 to 11
* Pistons moves to 0.1 to 8.5
* Cams moves to 0.1 to 3.5

0C
* bearings moves to 126 to 245 (400-790 for the 5W30)
* Pistons moves to 1.6 to 190 (5.5-630 for the 5W30)
* Cams moves to 1.6 to 87 (5.5-260 for the 5W30)
55C
* bearings moves to 15 to 30 (29 to 50 for the 5W30)
* Pistons moves to 0.2 to 23 (0.3 to 40.8 for the 5W30)
* Cams moves to 0.2 to 10.5 (0.3 to 17 for the 5W30)

Castrol Edge 25W50...At 100C operating temperature moves everything to the right.
100C
* bearings moves to 13.8 to 26.7
* Pistons moves to 0.2 to 20.5
* Cams moves to 0.2 to 8.6

0C
* bearings moves to 2520 to 4600 (400-790 for the 5W30)
* Pistons moves to 29 to 3560 (5.5-630 for the 5W30)
* Cams moves to 29 to 1633 (5.5-260 for the 5W30)
55C
* bearings moves to 65 to 125 (29 to 50 for the 5W30)
* Pistons moves to 0.8 to 98 (0.3 to 40.8 for the 5W30)
* Cams moves to 0.8 to 45 (0.3 to 17 for the 5W30)

The 25W50 was for demonstration purposes...you are right, it would heat quickly due to shear in the bearings, and cause a large amount of parasitic drag (25W70 in my J-Car in winter 15 years ago was like having the handbrake on...note, no blow-ups, and the cams were recieving oil quickly), and use a lot of fuel...

There are studies in the OTR equipment to reduce the heat transfer in the mid stroke range to reduce the local viscosity, and move that piston line back away from full hydrodynamic at mid stroke.

Interestingly too, is that the "perfect" lubricant, which was constant viscosity with temperature would need an entirely new set of AW additives, that were functional down to sub freezing temperatures.
 
Originally Posted By: fredfactory
Originally Posted By: Pontual

The AWs that are temperature related surfactants won't work at low temperatures, BUT, what about the solid lubricants, as MoS2 and graphite. The would shime in there reducing the wear at warm up.


Nobody uses graphite anymore AFAIK. ArcoGraphite bit the dust in the 1980's. Ceratec might help.


No, you can still get graphited motor oils, and also aftermarket additives with graphite in them.

Elf sells a mos2 + graphite oil.
 
Nice post. All makes sense and I have ran the IVA at lower temperatures and see lower numbers so it is defiantly on the sweet spot of wear.

Base oil is of little impact here, it's all about the chemistry. And driving rather than letting engine warm up at idle significantly reduces the camshaft loads.
 
Originally Posted By: fredfactory
The trick is to find AW additives which don't need high pressure and high temperature to work.

ZDDP works well at high temperatures. High viscosity itself protects cold. That middle region is served by moly, poly-esters, boron, etc.

Trying to prevent the picture below from happening:
toppistionbearing-300x283.jpg

When the engine is off the parts will over time settle to the shiny positions [rods and crank] you see on the bearing as well as that is the high wear area.
 
Originally Posted By: bobbydavro
I have ran the IVA at lower temperatures and see lower numbers so it is defiantly on the sweet spot of wear.


Great information, thankyou.
 
So, IF I understand this correctly, if I want to minimise wear (especially of the valve gear) at the expense of fuel consumption, I should put straight 40W in it.

That's nice to know, since (due to "emergency" replacement following a fairly massive oil leak), that's mostly what its got.

Might adopt it as a general policy.
 
Ducked...if you want to draw that conclusion, go your hardest...that's NOT my statement, recommendation, NOR interpretation of my work.
 
Originally Posted By: fredfactory
Originally Posted By: JHZR2
Originally Posted By: fredfactory
High viscosity itself protects cold.


Assuming you get flow... Which isn't guaranteed using sufficiently heavy lubes in low temps. And that other issues, like hydraulic tensioning of the timing chain.


The ADBV on oil filters should keep the journal bearings wet for the next cold start. Oil is there and getting pumped quickly 'cause the galleries are full always from the pump to the bearings. (Not sure about the oil being all the way up the pickup tube though.)
Cast-Magnatec markets their oil based on its sticky and stays on the cam lobes waiting for the next start.

Hydraulic tensioning problems are something I noticed on an '04 Chrys 2.7L v6 a while back, the timing chain flopped around on startup, then settled down, so good point there.
Oil drains from all the bearing journals and passage ways above the filter. That is why there are rattles when you start the engine . there is air in the oil passages.
 
Originally Posted By: CT8
Oil drains from all the bearing journals and passage ways above the filter. That is why there are rattles when you start the engine . there is air in the oil passages.


From the oil filter upward to the crank, the oil should stay in those passages because of the ADBV in the oil filter. I understand how a lot of oil will leak out the clearances in the rod and main bearing surface parts, yet the passages leading to it should be full of oil.

Refer to the diagram below, although that engine has the oil filter above the crank, might be engine design differences that would influence whether or not you have a "pre-charge" of oil (less air).

crankshaft-lubrication2.jpg


This is important on startup of course for all the Stribeck physics to work, the oil has to be there. Some thick oil is there anyway, as not ALL drains out of the crank and main bearings.
 
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Originally Posted By: bobbydavro
Nice post. All makes sense and I have ran the IVA at lower temperatures and see lower numbers so it is defiantly on the sweet spot of wear.

Base oil is of little impact here, it's all about the chemistry. And driving rather than letting engine warm up at idle significantly reduces the camshaft loads.


Great inside info bobbydavro, thanks. Yet, are you talking about having the cam lobes moving across the followers at higher (than idle) engine speeds makes more hydrodynamic happen? I'm confused by your statement about camshaft loads.
 
fredfactory,
it's SOP on a rebuild to run at a couple thousand revs for the sake of the cam rather than let it idle.

Look at the bottom line on the stribeck curve...the things that push you to the right are (more) surface speed and viscosity. The things that push you to the left are more load.
 
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