colder thermostat effect on oil

[demarpaint]

Changing a properly operating thermostat to a cooler running thermostat is a bandaid. At least that is what I was taught. Find the root cause of the problem and fix that.

 

[EvanD]

Originally Posted By: evandostert
I just dropped off my truck today for a colder thermostat from lingenfelter 160 vs 195 from chevy. I was wonderering what effects this will have on my oil???




ok back to the question please.

 

[UNC017]

Originally Posted By: demarpaint
Changing a properly operating thermostat to a cooler running thermostat is a bandaid. At least that is what I was taught. Find the root cause of the problem and fix that.


If you're trying to fix overheating, its a bandaid. If you're doing a complete re-tune for more power/performance and more aggressive timing advance WITHOUT having to use racing fuel, then not only is it NOT a bandaid, its a common approach used by everyone from Roush, Hennesey, Ligenfelter, etc. to Mopar Performance, Ford, and GM in various aftermarket and factory-supported modification packages.

It DOES have an application- this gentleman knows that and is simply trying to find out what price (in terms of shorter oil or engine life) he might have to pay for the choice to tune his engine this way.

WHY is that so complicated???? Aren't we gearheads here, or are we mindless slaves to keeping everything showroom stock??

 

[demarpaint]

Mindless slave? That's a new one. He is trying to fix an overheating issue it appears, perhaps a larger radiator to handle the additional heat is needed. As already stated all the 160* T stat does is deal with the minimum amount of heat, it appears it is the maximum amount that is the issue here.

As far as price paid, it could be increased engine wear when the vehicle is not loaded up, and sludge?

What do you suggest?

 

[Gary Allan]

Originally Posted By: evandostert
Originally Posted By: evandostert
I just dropped off my truck today for a colder thermostat from lingenfelter 160 vs 195 from chevy. I was wonderering what effects this will have on my oil???




ok back to the question please.


Quote:
Sorry, the question. If you're not out of open loop, plan on a substantial amount of fuel dilution. I don't expect any effects of moisture or whatever since you will have more than enough time at temp.


Well, you are out of open loop - so CHECK ...so no "inordinate" fuel dilution ...just normal from any potential shorter trip stuff.

So, my original .....(way back there) statement stands. I guess you'll experience less oxidation.

 

[Unleashedbeast]

Let me say again, my 1999 LS1 Trans Am had a massive sludge buildup after using a 160* thermostat.

Yes, I'm fluent with HPTuners and owned the software. My engine was tuned by me using a wideband over the course of a month. The tune was perfect, zero knock, perfect fuel trims (open and closed loop), etc...

After four years....went to install camshaft....and OMG!!!!

SLUDGE!!!!

This was with 3-5K OCI of Mobil 1 and German Castrol

 

[demarpaint]

That is "many times" the unfortunate outcome of the wrong T-Stat, tuned engine or not.

 

[Thermo1223]

Originally Posted By: evandostert
Originally Posted By: evandostert
I just dropped off my truck today for a colder thermostat from lingenfelter 160 vs 195 from chevy. I was wonderering what effects this will have on my oil???




ok back to the question please.


If you use an good syn-blend or syn. and change based on a used oil analysis which would be priceless if you spent lots of cash of mods. Then nothing you can't forsee.

IE You'll be just fine.

IMO I'd do this, pick a grade recommended for sustained high temp driving and then get that grade in syn since you will be towing. It can better withstand potential heat. Sample at 3k miles and see where your at and proceed from there.

In reality though you should try upping the octane next time anyway. From what I've read the SS can put out some impressive HP/TQ with boltons but all power may need a bit of extra protection if you tow. You can't have the ECU start pulling timing when you really need to get up that hill!

 

[EvanD]

Originally Posted By: Unleashedbeast
Let me say again, my 1999 LS1 Trans Am had a massive sludge buildup after using a 160* thermostat.

Yes, I'm fluent with HPTuners and owned the software. My engine was tuned by me using a wideband over the course of a month. The tune was perfect, zero knock, perfect fuel trims (open and closed loop), etc...

After four years....went to install camshaft....and OMG!!!!

SLUDGE!!!!

This was with 3-5K OCI of Mobil 1 and German Castrol

Now thats a great 1st hand experience to look at. Thank You good post.

 

[Gary Allan]

Quote:
Let me say again, my 1999 LS1 Trans Am had a massive sludge buildup after using a 160* thermostat.


How was this typically operated? A couple of scenarios should play out with a cooler thermostat in regard to oil temp. The peak temp might be shaved, or the curve to peak temp will be elongated beyond the point where the coolant starts to bleed off excess btu's instead of shoving them out to the oil as the next most sensible escape path.

I guess a couple of minutes could tip some scale if one never made the temp threshold to the point of purging event accumulations before that point.

I don't see the OP encountering this condition.

 

[edhackett]

Here's a good article on 160 thermostats that covers the effect on oil, wear, and performance.

http://www.carnut.com/ramblin/cool3.html

Ed

 

[EvanD]

I am going to follow up with a black-stone after a couple months. Will that show oil sludging? if so what reading are you looking at?

 

[Gary Allan]

Originally Posted By: edhackett
Here's a good article on 160 thermostats that covers the effect on oil, wear, and performance.

http://www.carnut.com/ramblin/cool3.html

Ed


Noted. It's not, however, going to necessarily alter his abuse on the oil.

This is a generalised statement and can vary with load and engine design but you can see why you want your oil over 212 degrees to boil out the moiture immediately!

The blow by itself is at some temp in the form of a saturated vapor. It will flash as it decompresses in the crankcase. I don't think that the coolant being @ 160F means that crankcase temps are conforming to it. Nor is it directly related to oil temp. Oil temp of less than 200F is flashing off moisture in excess of that being produced in the blow by. Just sat in the sun it will surrender it in vapor. The trick is to have it at a temp where it can release more moisture than is being produced by the combustion process.

..but it's something to think about. We're sorta taken out of that discussion in THIS case since he IS using a 160f thermostat. I think that it can and will impact a few things, but as long as his event duration is long enough and his time to temp is short enough, he won't be destroying the oil or forming sludge.

That's my opinion on it anyway. FWIW

 

[edhackett]

I think you are basically right Gary. I also thought the 212F comment was over the top, but the article is essentially correct.

As far as the effect on the oil goes, this would be a good case for the 3K/3 month OCI.

I am under the, maybe mistaken, impression that the OP thinks that installing a 160F thermostat and 160 tune will make is truck run at 160F in 115F heat pulling a boat with the AC on. That is just not the case. It's going to run at the same temp it did with the 195F thermostat in those conditions. What's worse an engine tuned for 195 F at 2XXF or one tuned for 160F at 2XXF? Intuition tells me the latter. His use and conditions have nothing to do with the benefits available from doing a power tune with a 180F vs 195F thermostat in a performance car.

Ditto on the that's my opinion on it anyway. FWIW

Ed

 

[Gary Allan]

Yeah, he will ultimately fall back on the capacity of the system. My personal choice would be to abandon the tune, go with 195F thermostat ..and just hang as much cooling hardware as required (bigger rad/oil coolers/whatever) to assure that it stays there.

The use of a 180F would probably served his needs for the lighter duty time with less impact on other things. When I had gauges to measure bypass coolant flow, I found that a 195F thermostat rarely maintained 195F coolant. 20F variance wasn't uncommon in the bypass/recirc circuit.

 

[UNC017]

NOW we're getting some constructive discussion.

I would also like to know what the driving cycle was in the 99 LS-1 that sludged. If you put an aggressive tune in a street car and then loaf it to and from work most of the time, I can certainly see this kind of thing happening. And its something that the OP should consider- but his application sounds like he's going for fairly frequent heavily-loaded use, and that should be less likely to generate sludge issues.

As for the use of used oil analysis to look for warning signs of sludge- I'd keep an eye out for high insolubles, high fuel dilution, high moisture, low TBN or excessive loss of TBN for the mileage on the oil (but that is very dependent on the type of oil you use since some oils resist TBN drop much more than others), and maybe even pay for a TAN test to look for acidic components. AFAIK there's no single parameter that warns of sludge building up, unfortunately.

 

[UNC017]

Originally Posted By: edhackett

I am under the, maybe mistaken, impression that the OP thinks that installing a 160F thermostat and 160 tune will make is truck run at 160F in 115F heat pulling a boat with the AC on

Ed


I'm not sure if that's his thinking or not. The impression I got was that he was getting some detonation and wanted to reduce that. If he's cooling system capacity limited, then you're dead right- a 160F stat won't change a thing because the cooling system's ability to reject heat to the environment gets *better* the higher the coolant temperature (IOW it takes a BIGGER radiator and/or cooling fan to keep an engine producing X horsepower at 160 degrees than it does to keep the same engine producing the same X horsepower at 195 degrees). But if he's not capacity limited and isn't actually overheating, a cooler tune could enable higher engine loading without detonation. I've twiddled with these very parameters on my '66 440 (see sig) because I built it with a tad more compression than I really should have. Lowering the coolant temperature actually lets me run a little more ignition advance without rattling, so in my case I get better efficiency with a cold T-stat. Yes, it would OVERALL have been better to lower the compression, run HOTTER coolant, and the same timing. But that would be a complete re-build of the engine. The down-side to running cooler is that it DOES sometimes become capacity-limited and the temp creeps up above the T-stat setpoint (sitting in heavy traffic with the AC blowing on a 100-degree day), but its infrequent and manageable in my case.

 

[djb]

There is an oil-related point you are missing.

A 160F thermostat is pointless in 115F weather. Under load the coolant temperature will increase well above that temperature, until there is a high enough temperature differential between the radiator and coolant air.

When the load is reduced, such as going slightly downhill or coming to a stop, the engine will quickly cool down to 160F.

The result will be many thermal cycles, not quite as severe as cold starts, but still putting high wear on tight clearance parts.

This use calls for a carefully monitoring wear products, and eventually switching to a thicker oil to maintain oil pressure with the looser parts. Right now you want an oil with lots of EP additives, but quickly switching to avoid high concentrations of metallic additives such as ZDDP to avoid needing to buy a new cat every emissions inspection.

I guessing someone is going to leap in with "get a bigger radiator to keep the temp at 160F". It won't work. The temperature differential has to be high enough to transfer the heat. It reminds me of a mil-spec that any part a soldier might touch had to be cooler than 160F. We couldn't meet that spec. If you put a camo painted piece of metal in the desert sun it will get hotter than that. No matter how big the heat sink, you must have a significant temperature differential to reject heat without evaporative cooling.

 

[EvanD]

Well I changed it out last night. Filled it up and then had a el-cheapo special coolant exchange done at pep-boys $79 special. I had a slight amount of dex sludge in the overflow tank.

Weather typical vegas sun still out 108 out still.

The results
Before at idle temps up to 220+ in traffic with A/C and normal driving in heat cruise at 195-210 slight amount of K/R on highway up to 8* (computer pulls a little timing to avoid detonation for those unaware of ls1 engines)

Now at idle temps at 190ish with A/C on and normal driving in heat 175-185 K/R almost unnoticible I saw 1.5* Without as much timing pulled the truck pulled harder and faster felt smoother.

For the guys who are overly concerned about the oil temps. This is a thermostat these are simply coolant readings so yes while my coolant is cooler and my engine runs a few degrees less, I am pretty sure my oil is still plenty hot enough and must be running at 200+ I will be checking that next.

 

[Gary Allan]

Quote:
avoid needing to buy a new cat every emissions inspection.


Tell me more about this here. I've yet to hear of mass cat failures over a lifetime of higher additive levels than are currently available unless you go out of your way to find them. SJ/SL ..all in use for a very long time and no one I've ever known has had cat change out due to additive levels. Old age (200k/13-15 years), falling apart inside, oddball design ..but never additive poisoning in any "premature" manner. You'll hear of a unicorn sighting every so often.

I'll speculate that the newer lower add levels are a preemptive reduction to allow the new wave of DI engines that are actually polluting more in actual engine emissions and relying on the cat to soak up the added unburned hydrocarbons. To get the 100k (or whatever it is now) they need increased cat efficiency retention beyond the former level.

Quote:
When the load is reduced, such as going slightly downhill or coming to a stop, the engine will quickly cool down to 160F. The result will be many thermal cycles, not quite as severe as cold starts, but still putting high wear on tight clearance parts.


..and this is different if the cycles were 195F-220F under the same conditions? My simple view sees cycling as cycling. Again, I don't necessarily support the use of a 160F thermostat, but I'm struggling to see your point.

Quote:
This use calls for a carefully monitoring wear products, and eventually switching to a thicker oil to maintain oil pressure with the looser parts.


I didn't see any report of substandard pressure. What might he expect as liabilities here.

Quote:
Right now you want an oil with lots of EP additives, but quickly switching to avoid high concentrations of metallic additives such as ZDDP to avoid needing to buy a new cat every emissions inspection.


Are there vendors that provide "quick change sumps"

If his conditions don't change ..and he needs lots of EP and whatnot now, why would this requirement quickly disappear? One would reason that additive concentrations under like conditions would somewhat be a constant.

Quote:
I guessing someone is going to leap in with "get a bigger radiator to keep the temp at 160F".


Well, no. Everyone would tend to say put in a big enough rad that it can maintain setpoint under most likely conditions that you are going to encounter. The setpoint itself doesn't have a whole lot to do with it over a given realistic span in reference to ambient. You can't set it at -32 and flash freeze your leftovers.

Quote:
The temperature differential has to be high enough to transfer the heat.


Isn't that sorta a self correcting thing? You'll have a given exchange medium that is what it is. You'll reach whatever temp that given medium allows in it's limits. High differential is not a requirement. For example, I can run my cooling towers at 170F and at a very slow flow rate. The ^T is tremendous. Nice and cool 100F cooling water for my condenser. Unfortunately now I can't slam the heat on the front end since the flow rate is so low and dwell time so long that I can't effectively cool the thing. So I open my valves ..send 3x the flow rate through the cooling jackets and reduce the differential to WHO CARES, but lower both inut temps radically. Now I slam the production end of the equation as much as I please ..and ITS differential to the cooling mass is greatly increased.