Cold Start Thickness - Dr. Haas

[Gary Allan]

I don't think anyone attributed you with the assertion. I would assume that you quoted a quote from the fine doctor who was quoting someone who has some misconceptions ..and that was quoted..

No ADFD reputation damage occurred in that post

 

[ADFD1]

Well thanks, I'll sleep better tonight.

AD

 

[Steve S]

Originally Posted By: BuickGN
Originally Posted By: oilyriser
Is cavitation during start up an issue? High viscosity should prevent oil from re-entering the suction region downstream of the load carrying part of the oil film, in a bearing.


You would have to be using an oil that was way out of the specified viscosity vs temperature range. As long as you're in this range there's little to no difference between say a 0w-20 and a 20-50.

I hate always using my GN as an example but I have never had signs of oil starvation in the bearings even though I set up my rods at factory clearances (mains are on the loose end of factory). I use 20w-50 in it year round and it's even seen Valvoline straight 60 and again these are stock clearances. I believe factory called for a 10w30 to a 15w40 but it's been a long time since I looked at the factory recommended oil.

What I'm trying to say is there's little gray area. You either have full lube to the bearings or no lube.
You didn't read the article ,there is supposed to be .

 

[Steve S]

Pull off a valve cover and start the engine.

 

[ADFD1]

Been there done that, makes a mess if you let it. But they claim the most engine wear occurs until that oil hits operating temp of 100C, then dramatically decreases. What exactly is the oil bath proving?

AD

 

[Gary Allan]

As we've more or less figured, it's a hard thing to factor/isolate. It's obvious that while you may alter where the curve starts in amplitude, you don't alter its duration. Hence while startup flow can surely alter it for lack of it ..having more of it doesn't eliminate it.

We're still left with having to breaking some thermal threshold for the cessation of startup wear.

 

[SpitfireS]

The high revving at start up is also (IMO) to warm up the cat as quickly as possible to reduce emissions.
More and more engines have some sort of air injection in the exhaust manifold for the same season.

It would be nice to see a start-up wear test of 2 indentical engines with only one difference: one has an coolant to oil heat exchanger.
The heat exchanger should be in the primary coolant loop, so coolant goes through it with the thermostat closed.
Coolant warms up quicker than oil, in most engines.. right?
That way you (slowly) transport extra heat into your oil when the engine is warming up and remove heat when the oil gets (too) hot.

How many of the engines in modern cars have a coolant to oil heat exchanger?

 

[Steve S]

There is plenty of oil ,the wear comes from the metals not at proper temps ,the pistons are oval till they heat up,the clearances change as the engine heats up, the air feul mixture is richer etc. The engines that last the longest are the ones that spend most of their lives at operating temperatures.

 

[Taylor]

So get an oil heater, a block heater, use a "thin" oil, and put a de-humidifier on your intake. Your motor will outlast you!

 

[Doug Hillary]

Hi,
ADFD1 - I was aware you were quoting from Chapter 102 from where ever (Mr Haas?)

I was just endeavouring to establish that the quote was wrong - I was aware that it was not from you

Seems funny that quotes from "experts" from all over the world get legs and just keep running....................................

 

[Gary Allan]

Quote:
How many of the engines in modern cars have a coolant to oil heat exchanger?


Most Audi/VW ..a few others. Mid 80's through some 2000+ Fords.

 

[BuickGN]

Originally Posted By: demarpaint
Great point Jim! I'm enjoying this thread too.

It's a shame they can't program into the EFI start-up a second or two of lower rpms just to get some oil around before the engine goes up to 1500 rpms. My new Jeep seems to come to life a lot faster when starting than my older Fords do, the seem to crank a tiny bit longer.


This is something I hate about the Murano, it instantly shoots to 1,500rpm on a cold morning. It only stays there for 10 seconds or so but I hate the fact that so much load is placed on it and so many rpms instantly. Oil pressure light goes out instantly too but I would feel more comfortable with a more gradual ramp up, even if ramped up over the course of a second or two. I got to this one early, dumped the factory fill and refilled with ACD for use year round.

My TL barely has a high idle. It will hit 1,200rpm only on mornings that are colder than 15F. At 32 it hits about 900rpm. The coolant warms up extremely quickly, it's at the normal spot on the guage within a minute and a half on a 32 degree start if I drive it immediately. I've given serious thought to adding an oil to coolant heat exchanger but I'm afraid this will slow the heating of the coolant.

Any thoughts (Gary) on the potential slower coolant warm up?

I believe that it's the lack of heat in metal parts, specifically pistons and cylinders that cause the warm up wear. I'm not sure if it makes sense (assuming I'm right) to install an oil to coolant exchanger since I put priority on getting the cylinders up to temp over bearings.

 

[demarpaint]

It's funny that we think 1200-1500 rpms are a lot, and they are. But how about the days of the carb when some of them idled at about 2000 rpms and you had to mash the pedal to get them off that fast idle cam. Those were the days.

I really think they should/could program the idle speed to step up 2 seconds after a start from lets say 600 rpm to 1200 rpm and then back down again.

Just the change over from the carb to EFI increased engine life a tremendous amount.

 

[Gary Allan]

Quote:
Any thoughts (Gary) on the potential slower coolant warm up?

Sure. I don't think there's any free ride on heat. But the issue with that is fuel enrichment and not total engine warm up. There's lots to think about. You'll shorten the time to temp for the oil by about 40%+/-. Where it normally takes 20 minutes or 12-15 miles as it evidences full engine warm up, it will now take 9-10 minutes for the oil to reach coolant temp.
Quote:

I believe that it's the lack of heat in metal parts, specifically pistons and cylinders that cause the warm up wear. I'm not sure if it makes sense (assuming I'm right) to install an oil to coolant exchanger since I put priority on getting the cylinders up to temp over bearings.


I tend to lean toward the ill fitment of expanding parts but I don't see the pistons and jackets suffering here beyond a little more time to end the fuel enrichment process.

Let me see if I can express this well enough since you kinda get into a thermal rob Peter to pay Paul situation. You've normally got tons of waste btu's just going out the rad via the thermostat. This is typically way before you ever reach anywhere near coolant temps with the oil in a non-exchanged environment.

With oil temps usually being the indicator of full thermal saturation, I can't see it NOT shortening the event by applying the waste heat to the oil. You're flooding the oil with thermal energy that would normally only get to it via the warming parts that are soaking them up in the warming/expansion process. You're providing less outlet differential/potential for the migrating heat attempting to leave the engine via the oil.

There's one side effect that I really can't explain ..but it's an observation in my usage. Once you reach equilibrium, it appears that it's easier overall to cool the engine. I imagine it's the flow differential of the coolant vs. the oil flow, but I'm always locked down against my thermostat setting unless I'm sitting still. Before I installed the exchanger, I'd be up a tad at highway speeds in summer temps with the air on. It's rock solid after the install.

That is, before oil cooler heat exchanger - hotter coolant temps at higher engine output. After exchanger install, lower coolant temps at higher output levels.

 

[Big Jim]

Originally Posted By: demarpaint
It's funny that we think 1200-1500 rpms are a lot, and they are. But how about the days of the carb when some of them idled at about 2000 rpms and you had to mash the pedal to get them off that fast idle cam. Those were the days.

I really think they should/could program the idle speed to step up 2 seconds after a start from lets say 600 rpm to 1200 rpm and then back down again.

Just the change over from the carb to EFI increased engine life a tremendous amount.


The Lincoln LS goes right to nearly 3,000 RPM on a cold start. It prompted a lot of owners to request it to be adjusted down. Too bad there is no adjustment, it is computer controlled.

 

[BuickGN]

It would be nice to let the coolant get up to full temp and then allow the heat exchange with the oil begin. Seems like the best of both worlds. Coolant would warm up like normal and I doubt it would make a difference in time to full oil temp.

 

[Gary Allan]

Most of the advanced and exotics have oil thermostats. They also may have bigger sumps.

In my observations over varied starting temps (like mid teens through just 85F), you reached the major gains at about 9miles/9minutes. The number may vary (let's say 155-170f) but the time to full temp would be the same. It's really creeping for the last 10f and will back right down when power is removed. It was, in my case (reading from oil filter output) immediate. Like from 213-215f to 190-195f in seconds.

The difference in time to thermostat setting, other than the natural impact of lower ambient temp, in my case have been on smaller engines with unremarkable power density. For example, my 2.5 engine probably doesn't even need the radiator in sub freezing weather for anything other than highway usage.

When I first started my 0w-10 oil trials, I attempted forced heating and cooling on my 3.0 Mitsubishi. My goal to simulate a smaller sump for startup (the idea came from a member named Curious Kid, iirc) and introduce more oil after warm up. I couldn't make a 5 quart sump into a 2 quart, but I could make a 7-9 sump look like a 5. I also wanted to have the advantages of a 0w-10 for warm up, but wanted to manipulate its hot temp to 180f to make it appear like a 20 grade. I used Ford Crown Vic adapted heat exchangers (they take a 1/2 NPT or 3/4-16 JIC thread easily, btw). I also used a couple of tandem'd Eaton tow motor transmission heat exchangers. There I used oil thermostats as coolant thermostats for the Eatons in an attempt to sequester the coolant until it reached 180F.

The bottom line in that whole setup (above) was that I found that actual coolant temp varied more than I expected. That is, even a 195f thermostat produced 20f+ dips in intake manifold outlet temp (temp sensor location).

Granted I couldn't really take the time to explore any and all interesting side effects as I was playing around in novice/hobby grade experimentation. It did teach me that there's a lot more complexity to managing things into the narrow confines that we want ..but also that there's an ample amount of forgiveness in the margins.

 

[SpitfireS]

Originally Posted By: Gary Allan
With oil temps usually being the indicator of full thermal saturation, I can't see it NOT shortening the event by applying the waste heat to the oil. You're flooding the oil with thermal energy that would normally only get to it via the warming parts that are soaking them up in the warming/expansion process. *During warm-up I don't think you're flooding the oil with heat as the coolant itself is heating up and from the start it can slowly exchange heat with the oil, the heat exchanger is in the primary loop* You're providing less outlet differential/potential for the migrating heat attempting to leave the engine via the oil. *You mean during the start-up period?*


IMO you're not robbing Peter to pay Paul.
At a cold start, Peter and Paul have the same amount of money, being none.
Peter and Paul are only happy if they have they have roughly the same amount of money.
As soon as the engine starts, Peter is making lots of money while Paul has a moderater income.
Pretty soon Peter has more money than he can handle and is asked to give it to the IRS.
There is your robbery!
IOW there is a third party involved here.
Pauls account is still slowly building up.
Both are not happy.
Before Peter has more than he can handle he should give some of his money to Paul.
Advantage: they both get equally rich a lot sooner.
Where is the catch?
Is there a catch?

The IRS will get their share anyhow.

The visosity of the oil during start up could be the amount of money Peter is giving Paul and/or the hight of Paul's income.

 

[BuickGN]

Originally Posted By: SpitfireS
Originally Posted By: Gary Allan
With oil temps usually being the indicator of full thermal saturation, I can't see it NOT shortening the event by applying the waste heat to the oil. You're flooding the oil with thermal energy that would normally only get to it via the warming parts that are soaking them up in the warming/expansion process. *During warm-up I don't think you're flooding the oil with heat as the coolant itself is heating up and from the start it can slowly exchange heat with the oil, the heat exchanger is in the primary loop* You're providing less outlet differential/potential for the migrating heat attempting to leave the engine via the oil. *You mean during the start-up period?*


IMO you're not robbing Peter to pay Paul.
At a cold start, Peter and Paul have the same amount of money, being none.
Peter and Paul are only happy if they have they have roughly the same amount of money.
As soon as the engine starts, Peter is making lots of money while Paul has a moderater income.
Pretty soon Peter has more money than he can handle and is asked to give it to the IRS.
There is your robbery!
IOW there is a third party involved here.
Pauls account is still slowly building up.
Both are not happy.
Before Peter has more than he can handle he should give some of his money to Paul.
Advantage: they both get equally rich a lot sooner.
Where is the catch?
Is there a catch?

The IRS will get their share anyhow.

The visosity of the oil during start up could be the amount of money Peter is giving Paul and/or the hight of Paul's income.


I totally agree with that. Only thing I would change is to let Peter make his entire fortune before he starts giving excess away and bringing Paul out of the ghetto.

 

[Gary Allan]

Quote:
*During warm-up I don't think you're flooding the oil with heat as the coolant itself is heating up and from the start it can slowly exchange heat with the oil, the heat exchanger is in the primary loop*


Coolant warms much faster than the oil. You're prematurely introducing heat to the oil at a higher rate at an earlier point.

Quote:
*You mean during the start-up period?*


Yes ..as SAE defines start up as anything other than "steady state" (and Castrol for that matter: "90% of all wear occurs at startup!" - same "startup" ..different impression) ..which is typically the first 20 minutes of operation. Most engines spend the vast majority of their lives in the start up state (keep in mind that the wear curve isn't linear).

Oil temp, in non-exchanged engines, tracks the thermal saturation curve and, when normalized, marks the onset of "steady state" ..and the cessation of all startup wear. This takes about 20 minutes.

Coolant temp is normalized at a much earlier point in the startup process. It's dumping heat long before 20 minutes. Taking that waste heat, and artificially inducing it into the oil, shortens this oil warming process. One may reason or could reason (READ: SPECULATE)that introducing this abundant waste heat into the oil would limit or decrease the normal shedding heat path that normally occurs in the 20 minute process that occurs in non-exchanged engines. That is, pistons and all other parts that are amassing heat, won't have as cold a medium to deal with in "warming up". The oil won't "drag them down" with being cold for as long.

Did I assemble that logic train in a digestible manner? I'd love Doug Hillary to shed any insightful input.