...or is there no difference in how efficiently the 928 engine cools with different oils?

H2

 

Neither synthetic or dyno oil will do very well in the radiator.

 

Well...oil -is- a significant cooling agent in a motor.

The quick answer is "yes"...the best answer is "You may never know" and "Its not worth picking your oil via it's cooling properties, pick it by appropriateness to the use".

 

significant from what perspective? the oil is over the heads, (not inthem like water) , around the cams, and in the pan, squirting through the crank and pistons, but the main heat is in the cylinderwalls and through the heads where the WATER does most the work by a significant amount. probably more than 90%. you can probalby run an engine with no oil and never over heat it, but im sure other things would be failing! . look at the flow of the water pump, vs the oil pump. the water pump is exchanging water at much less pressure , and a much higher flow. With oil it is just the opposite.

the point here is, the oil types dont have much to do with cooling, especially as far as differences between types, weights and brands.

 

Your **** would fail without it cooling what it touches.



See how many words you could have saved in your lifetime by just sayin "Ya..he's right".

 

The oil removes heat from the engine and I would agree with Mark that the Lion's share of the heat removed is by the main radiator. The oil cooler is much smaller in surface area but the oil temp is doubtless quite a good bit higher than the water temperature [note: heat transfer is proportional to log mean temperature difference- if you know what that means]

Synthetics improve lubrication by providing adequate lubricity [ilm strength] at lower viscosities and retain their properties much longer due to much more even molecular chain length. If lubrication is equal [syn compared to mineral based] and the syn has lower viscosity, drag will be reduced thus more power is available to the wheels and less heat is generated due to reduced [frictional] drag. Whether the quantities are significant I'll leave to others but probably not.

My experience with synthetics is that more oil is consumed and the lighter the oil the quicker it goes through the engine. The latest Porsche turbo's [911 and Cayenne's] are filled with light weight syns [0w40 Mobil 1] and they go through oil at the rate of about 1 litre every 1000km's [can be more] but they have no issues with wear that I know of.

In the case of 928's well I guess they were originally designed with mineral oils primarily in mind. One should also consider that technology has not stood still and mineral lube oils today are quite a bit superior to mineral oils of 20 years ago. There has also been a lot of debate about the zinc content needed to support long term operation of the hydraulic tappets. My preferred oil of choice is Redline 20w50 synthetic- their tech rep told me it has adequate zinc content. Unfortunately I have not been able to get it of late so reverted to Castrol GTX mineral based oil which I change regularly [about every 5k km] and use a 20w50 weight. Using mineral oil my oil consumption dropped noticeably. In our climate no issues with cold start performance. If I was in the UK I would be looking for something 10w50 perhaps, especially for winter use.

My 50 cents worth- hope it is of interest.

Regards

 

Does synthetic oil cool "better" than dino oil......I would say no.....assuming oil of equal quality is compared

HOWEVER...synthetic oil can be ran much hotter for much longer without damage to your engine than dino oil.....

For example we ran Amsoil 15-50 racing for 18 hours on track without changing it at our last lemons race....including when the car was overheating big time and the oil temp was pegged at 300F.....I sent the sample in to be analyzed and it came back PERFECT...no indication of overheating, when clearly it was....

 

Correct no big difference in cooling "synthetic" just stays thicker at high temps.

 

Looking to lower your temp guage needle? No, the cooling system controls that.

Synth - more resilience to stress breakdown, longer change intervals, exaggerates existing leaks, more expensive.
Dino - appropriate for non-high stress use, less expensive.

There are also other considerations like Brand fluctuation, weight, typical weather the vehicle is operated.

There are some very good Dino oils and synthetic is never a “must have”, but under stress a synthetic can provide addt’l performance which makes it more attractive to lower potential failure variables.

Most people don't expose their car to extreme use.
Most people like to know they have synthetic for piece of mind.
Most people change their oil far too frequently.
Most people should save $$ running a more than adequate Dino oil.

 

Great observations...thanks! I think I'll stick with Dino for my application (mostly street) and change oil more often.

 

Yer making that up. Then again, 68% of all statistics are.

it depends on the car design. My 928 uses two-plus gallons of oil and has an oil cooler because it play a significant role in cooling the engine.

I've seen it on other cars where running the oil low, without bringing on an idiot light, is clearly seen on the temperature gauge.

to the OP question:

I'd venture that viscosity plays a bigger role. With a thinner oil you're pumping more through and that cools the parts. The specific heat of the oils will be very similar and I have no idea which will be higher or if one type is always more or less.

Reminds me of old oil threads where one gentleman always said flow was an important characteristic of oil and that viscosity, per se, was a bad thing as it limited that. Viscosity is an indirect measurement of shear strength which was what you want to keep metal parts apart.

Makes me think that if you run an engine with a thinner synthetic oil because it lubricates satisfactorily then it'll be cooler.

 

For shame!

OK, you're right. But take apart an engine that was run exclusively on synthetics and you won't go back. Since I expect to take apart my engines multiple times (because I'm a freaking Genius!) and I track the cars I will run synthetics except during break-in periods.

 

Synthetic oil doesn't smell like dino oil if you have some leaks, the rest is gravy.

 

again, sure, things will spot fail witout oil, and yes, its due to temp, so from that perspective it does its job, but then thicker oils at temp tend to protect better, and preserve oil pressure which has been noted to kill engines too.

i prefer an oil like redline or amsoil that preserves the 5 bar pressure at 280F. you may disagree. much of the evidence is weak on both sides.

the oil flow pales to the water flow which is flowing around the hot areas with a lot more surface area and flow rates. the oil is run in specific areas, with much less flow. ive run my car with and without an oil cooler and didnt see a huge difference in race temps for oil and certanly not water.

the OP asked if different TYPES of oil will have different coolign properties. i woudl say, no. if there were differences, they would be subtle at best.

so, im not goint too say your right, because you have no basis for being right!
remember you are the guy that thinks your stock mazda on street tires goes 115mph through turn 8 at thunderhill.
Hey, im just joshing with ya!!

 

anderson still runs kendal 20-50 i think (dyno oil with no issues) I did too for a long time. the graphs show synthetics after many 1000s of miles with at spec viscosity. dyno oils might only be good for 1000miles. when i ran dyno oil i just changed it more often. however, to glen's point and my experience too. an engine that runs synthetic seems to end up a lot cleaner. plus, look at the luck i have had with my racers over the past 15 years using it in 5 platforms of the 928. never had any issues, no failed engiens, lots of racing , and clean motors when they have been torn down.