temp bet test !!!

[swarfeater 49]

I was arguing (discussing) the benefits of synthetic oil, as I know from experience with my own devices, with a friend of mine. I am a strict user of synthetics and use them in every application, except 2 strokes. my friend is a " any quality oil is good enough for anything".  he would not believe the evidence I saw with my own eyes and was willing to put his money where his mouth was( when I suggested it).  the horse was the tool, and a field of grass (hay field, with very good grass) nearly a foot high and wet was the test. the grass was tough enough that the 312-8 needed low range, 2nd gear to do it !!! we divided the grass into 3 equal sections, drained the 5w50 mobil 1  that I run and poured in the 30w (brand name).  I used a fluke with a thermocouple and the temp measurements were taken by shutting off the engine, pulling the dipstick and measuring the oil temp( all temps are oil).the engine was restarted and allowed to cool a bit with a fast idle for a few minutes, then oil drained and changed.  the 3rd test was wrapping(rewrapping) the muffler with header wrap.  this I have been using on the horse for a year or so and is worth every penny !!!  my friend paid up, and vowed to switch.. the wrap may be hard to believe, but the fact is that everyone knows  how much heat the muffler pours off when working the motor hard. I guess the radient heat pouring off just bakes the block more efficiently than the air cooling can remove it. the fluke was not calibrated so the numbers are relative to each other only, but accurate in their spread. anyway, take it for what its worth. but numbers don't lie, and the cooler ride when driving into a headwind are something you have to do to know how much better it is.

[Racinbob 11,925]

That's interesting. I never thought about heat wrap on a muffler. Synthetic is certainly a better oil that conventional but in some ways I's have to agree with your friend. For 40 years I was using conventional and had several vehicles with well over 200k miles. I never had an issue or any sludge buildup. Granted, a big part of that was due to my religious oil changing but it worked for me. Even after synthetic became the 'thing' I didn't use it because I was changing oil every 4-6 weeks due to the miles I was driving and the cost difference. Longer intervals were out of the question and synthetic couldn't sway me to extend them. Now that I'm retired I am using synthetic in my truck because I'm not putting the miles on it.

[Tankman 3,523]

Nice test. Of course I never would have imagined the results.

 

I too believe the synthetics are #1, the bestest!

 

I use conventional engine oil but, think I'll make the switch. I always use Mobil 80W90 synthetic gear lube.

Years ago I used to deliver the gear lube to UPS, was all they used in their delivery trucks; rear axle.

 

With their data base, the synthetic lube was profitable. 

 

Then a friend who raced autos told me he got one race per rear until he changed to Mobil 80W90 synthetic gear lube. His race car rear then lasted for three races. 

[Save Old Iron 1,571]

will combustion chamber deposits increase at lower engine temperatures ?

 

will fuel efficiency drop off at lower engine operating temperatures ?  Carnot thermal efficiency concerns?

 

if the purpose of the experiment is to lower oil temperatures then yes, synthetics do indeed transfer heat better - usually about 6 - 8% better and that agrees with your findings.

 

if the lowest temperatures possible are the holy grail, why not run automotive engines without a thermostat in summer months?

 

Discuss.

Edited May 15, 2014 by Save Old Iron

[C-101plowerpower 1,606]

Nice test. Of course I never would have imagined the results.

 

I too believe the synthetics are #1, the bestest!

 

I use conventional engine oil but, think I'll make the switch. I always use Mobil 80W90 synthetic gear lube.

Years ago I used to deliver the gear lube to UPS, was all they used in their delivery trucks; rear axle.

 

With their data base, the synthetic lube was profitable. 

 

Then a friend who raced autos told me he got one race per rear until he changed to Mobil 80W90 synthetic gear lube. His race car rear then lasted for three races. 

 

i think i have read this before? i've heard that synthetic oil lubricates better, but if you just overhauled the engine it's better to use mineral oil in it so the engine breaks in faster. don't know if this is true or not, it's just what i've heard

 

 

Koen

[bmsgaffer 2,053]

will combustion chamber deposits increase at lower engine temperatures ?

 

will fuel efficiency drop off at lower engine operating temperatures ?  Carnot thermal efficiency concerns?

 

if the purpose of the experiment is to lower oil temperatures then yes, synthetics do indeed transfer heat better - usually about 6 - 8% better and that agrees with your findings.

 

if the lowest temperatures possible are the holy grail, why not run automotive engines without a thermostat in summer months?

 

Discuss.

 

Haha, engineer! (I was going down the exact same path)

 

I use dino oil because my engine has run for 30+ years on it so I'm thinking that it will be alright for the long haul. Anyway its hard to find synthetic 30W and the kohler manual specifically states more carbon build up by using a multi-weight (i.e. 10w30) in the summer.

 

I DO use synthetic in the hydro trans because of the significant shear/wear there and heat is NOT wanted there. I use whatever I got in the proper weight for the 8 speeds syn or dino doesn't matter.

[swarfeater 49]

you have to consider that the lower temps are from one reason and one reason only, less friction. I don't know what or any side effects may be, but I do know that a switch to synthetics everywhere, exhaust wrap and electric fans raised the fuel mileage 3.5 and 5+ on the highway on my 4 liter ranger. running temp is the same, but that cannot change with a thermostat, but the truck sure does take longer to warm up. oil temp dropped 20+ degrees, to near 30 below water temp. circle track magazine did an article a while back, some of you may have seen, where they took a 500 hp circle track race motor and used a dyno to drive it rather than the other way around. what it found was that it too 275HP to drive the motor at 6000 rpm. that's 275 hp worth of friction in a 500 hp motor. one big thing it found was that oil in the case is not in the form of droplets, but rather a sludge that was dragged around by the crank and had to be beaten through by the rod big ends every revolution, hench the reason every performance motor in the world now uses crank scrapers and screens. anyway, the heat wrap on the muffler is a winner, period !!! the hood alone runs 150 degrees cooler and the heat pouring back to the driver is history, just plain more comfy, and it a bit quieter too.

[bmsgaffer 2,053]

Well, technically the lowered temps can be from at least two things: less friction and/or better heat transfer as SOI stated. Synthetic conducts heat better.

 

I cant argue with the exhaust wrap, that's neither here nor there.

 

With the air-cooled engines there is no thermostat, so they have no control of the temperature other than what the engineers designed into it with the size of fins, type of oil, size of blower, etc. If you cool down combustion too much you can cause incomplete burn which will cause additional carbon build up. Hot combustion will be more complete and efficient.

 

HOWEVER, (the BIG if here) on these engines without water cooling, oil temps are NOT an accurate gauge of combustion temperatures. There's a LOT of heat transfer between the combustion chamber and the pool of oil in the pan. It MAY just be cooler oil now that it conducts heat so well and didn't change the combustion at all.
 

Just my :twocents-02cents:  (thats $0.04 )

 

Basically all the theory is speculation until accurate tests can be done on controlled environments with controlled loads and lots of temp monitors... too many variables... Basically, far more than is worth on these old engines

[Racinbob 11,925]

Well put Brandon. Basically what I was trying to say is that synthetic is a better lubricant but it comes with a price. If conventional has worked 100% for me for 40+ years why change. OK, I am using synthetic in my truck now that I can justify it with the lower miles I drive now. I think it might be a bit of an advantage for me now due to the much longer time between changes. Not mileage wise but time wise. I can compare it to something I heard at a range not long ago. A guy was shooting trap and got a perfect 25. He was shooting his low/mid range field gun. One of his buddies told him that he should get 'one of these'. It was a high end specifically build trap gun. The guy simply told him "Would I shoot a 26 with that?" Good answer.

[Save Old Iron 1,571]

you have to consider that the lower temps are from one reason and one reason only, less friction.

not even close to being true

 

example - leave everything in the engine the same, install an external oil cooler - much lower oil temp and friction stays the same.

 

familiarize yourself with the property called specific heat. it explains 80% of the lower temps w/ synth oils.

Edited May 15, 2014 by Save Old Iron

[dcrage 630]

not even close to being true

 

example - leave everything in the engine the same, install an external oil cooler - much lower oil temp and friction stays the same.

 

familiarize yourself with the property called specific heat. it explains 80% of the lower temps w/ synth oils.

 

So synthetics have that much greater 'heat capacity' than petroleum based oils??

[Save Old Iron 1,571]

I haven't had my thermal dynamics books out since the late 70's when I worked at the Corning Glass Works. I used to know a bit about the subject but Heat Capacity and Specific heat are two different terms but define similar properties of materials.

 

I don't argue synthetics do lower friction, but the overall lowering of the "system" temperature the oil is used in (the Kohler K engine) has to do with many variables in the oil. The ability of the synthetic oil to absorb more heat from the system (mostly thru contact with the aluminum piston that has a much higher thermal conductivity than the cast iron cylinder walls) is greater than conventional oils. The ability of the synth oil to TRANSFER the heat to the cast iron oil pan is also greater than the conventional oils. I also believe the contact between the synth molecules is better with the cast iron due to smaller and more consistent size of the synth oil molecules - i think that's the right term ???  Imagine transferring heat thru two large aluminum spheres that only have a little contact surface between them  versus hundreds of smaller aluminum spheres occupying the same area. The contact between the smaller spheres is greater and more heat is transferred thru the material.

 

The MPG increase in the Ranger is substantial. Replacing a defective thermal clutch on a pulley mounted fan with  electric fans can by itself make a substantial increase to MPG. The wrapping of the headers lowering the under hood temp - a no brainer as you limit the exhaust heat lost in the headers and force the heat under the floor boards and into the under car portion of the exhaust system. Underhood temps will undoubtedly go down. As far a wrapping the whole exhaust system, I believe most car manufacturers address this issue by using stainless steel in the exhaust system. Stainless has a much lower heat transfer ability than carbon steel and will not allow the heat in the exhaust system to be dissipated as rapidly under the vehicle.

 

The biggest gain in MPG I have seen in my vehicles comes when I am conscious about my driving habits. Driving at speeds closer to the speed limit, limiting unnecessary fast acceleration. keeping tire pressure correct and consolidating trips into one all lead to greater increases in my "miles per tankful" than any other addition to  vehicle.

Edited May 16, 2014 by Save Old Iron

[dcrage 630]

Thanks for the tutorial -- I had never heard about the greater ability of synthetics to transfer heat -- Doesn't suprise me in the least that this is the case -- Just never thought or heard of it before