Oil and Oil...
- Thread starter lali
- Start date
Well reading what Thom and Simon have written, maybe the 10w60 starts off too thick but degrades quickly to the equivalent of a 10w50 or 10w40, if so that would make them both correct.
Thom whilst I noted and respected your experience with destroyed engines have they all been treated the same way? always used the respective oils? ,driven the same way from cold?, always run with oil at similar levels? driven to the limiter regularly or not, always the same make of filter, good thermostat so correct temps, driven mainly on repeated short journeys or long motorway runs? etc. etc.
Tony
Thom whilst I noted and respected your experience with destroyed engines have they all been treated the same way? always used the respective oils? ,driven the same way from cold?, always run with oil at similar levels? driven to the limiter regularly or not, always the same make of filter, good thermostat so correct temps, driven mainly on repeated short journeys or long motorway runs? etc. etc.
Tony
I might be being stupid here but isn't the cold viscosity of the oil the crittical factor. I would have thought that 10W/60 and 10W/40 are the same weight when cold ie they are a muti-grade oil and have the same properties as a 10 grade oil when cold but a 60 grade when hot, in the former, and a 40 grade in the latter. This being the case, if the engine can "cope" with 10 weight oil when cold it shouldn't have a problem with 60 weight when hot, assuming this isn't any thicker than cold 10 weight.
I would have to suggest that Thom's friends experiences are relative to race engines which will, by nature, run much hotter, and harder, and perhaps find advantage in the additional protection of the 10w/60 oil at a higher than average operating temperature. For "normal" use, the manufacturers recommendations are obviously a great guide.
However, as I understand, RS 10w/60 wasn't available when the 944 was produced, and is only available from Castrol at this specification. Oil technollogy has moved on in the 20 years since the 944 engine was developed. If 10w/60 had been available 20 years ago and, if it didn't mean specifying one manufacturer, isn't it concievable that Porsche might have recommended 10w/60.
From a performance, ecconomy point of view the "thinner" the oil is the better. From an engine protection point of view, assuming the oil can get to where it is needed, and doesn't blow any seals, then it is the strength of the oil which must count - its abillity to maintain a film between moving surfaces and to transfer heat is parramount.
Again, if the oil is sufficiently thin to move around the engine when cold (10w/xx) it would seem that it could give more protection if it can retain more viscosity when hot.
There is obviously a caveat here. Oil, when cold, is too thick to thrash your car. There must be an optimum viscosity when thrashing isn't going to cause problems and again a point when the oil becomes so hot that it looses film strength and metal to metal contact occurs.
I'm just a humble joiner, not an oil expert, but the above points seem to reasonably sound to me.
However!!! An oil was produced that had all the strength that you could wish for - it may have been developed for NASA? It was clear and as runny as water. Apparently, no body would buy this product because it didn't seem to have the properties they associated with oil (thick, coloured and slippery) despite the fact that it would do everything and more that their current oil would. This being the case - it would seem that may not matter a fig how "thin" the oil is provided that it has the "performance" to retain its desirable properties when subjected to heat, compression and shear.
I had a Ford racing engine built and the engine builder would only guarentee the engine if I use Castrol 10w/60. Apparently, it had to be that "heavy" to maintain pressure within the hydraulic tappets when hot. Doesn't a 944 have hydraulic tappets? [
]
I would have to suggest that Thom's friends experiences are relative to race engines which will, by nature, run much hotter, and harder, and perhaps find advantage in the additional protection of the 10w/60 oil at a higher than average operating temperature. For "normal" use, the manufacturers recommendations are obviously a great guide.
However, as I understand, RS 10w/60 wasn't available when the 944 was produced, and is only available from Castrol at this specification. Oil technollogy has moved on in the 20 years since the 944 engine was developed. If 10w/60 had been available 20 years ago and, if it didn't mean specifying one manufacturer, isn't it concievable that Porsche might have recommended 10w/60.
From a performance, ecconomy point of view the "thinner" the oil is the better. From an engine protection point of view, assuming the oil can get to where it is needed, and doesn't blow any seals, then it is the strength of the oil which must count - its abillity to maintain a film between moving surfaces and to transfer heat is parramount.
Again, if the oil is sufficiently thin to move around the engine when cold (10w/xx) it would seem that it could give more protection if it can retain more viscosity when hot.
There is obviously a caveat here. Oil, when cold, is too thick to thrash your car. There must be an optimum viscosity when thrashing isn't going to cause problems and again a point when the oil becomes so hot that it looses film strength and metal to metal contact occurs.
I'm just a humble joiner, not an oil expert, but the above points seem to reasonably sound to me.
However!!! An oil was produced that had all the strength that you could wish for - it may have been developed for NASA? It was clear and as runny as water. Apparently, no body would buy this product because it didn't seem to have the properties they associated with oil (thick, coloured and slippery) despite the fact that it would do everything and more that their current oil would. This being the case - it would seem that may not matter a fig how "thin" the oil is provided that it has the "performance" to retain its desirable properties when subjected to heat, compression and shear.
I had a Ford racing engine built and the engine builder would only guarentee the engine if I use Castrol 10w/60. Apparently, it had to be that "heavy" to maintain pressure within the hydraulic tappets when hot. Doesn't a 944 have hydraulic tappets? [
]
oilman
New member
The truth is relatively simple.
If they'd been around when the 944 was built, Porsche would have specified 0w-30/40 or 5w-40 oils as they do today. The move towards thinner oils is where the OEM's are going not thicker.
The benefits of thinner oils outweigh the benefits of thicker ones and the basic ones are:
Fuel Economy
Better Power delivery
Better flow when cold
Narrow viscosity range
Better all year round compatibility
The key point here is about viscosity range and the additives required (VI improvers mainly) to make a multigrade work as a 10w and an sae 60.
A petroleum based 10w oil requires bucket loads of VI improvers (polymers) which uncoil with temperature increasing the viscosity, unfortunately these polymers are prone to "shear" meaning that the oil stays in grade for less time.
This is the main problem with wide viscosity oils unless they are made with "synthetic" basestocks which require little or no VI improvers to prop them up because they are thermally stable to start with.
The whole point that I'm making is that a 10w-50 or 15w-50 if it's a good oil using decent basestocks is a better bet anyday than a "dino" 10w-60 as it will stay in grade for longer, giving better protection.
You are indeed right about the 5w, 10w protection, believe me a 20w is not much good for your car on chilly mornings!
Cheers
Simon
If they'd been around when the 944 was built, Porsche would have specified 0w-30/40 or 5w-40 oils as they do today. The move towards thinner oils is where the OEM's are going not thicker.
The benefits of thinner oils outweigh the benefits of thicker ones and the basic ones are:
Fuel Economy
Better Power delivery
Better flow when cold
Narrow viscosity range
Better all year round compatibility
The key point here is about viscosity range and the additives required (VI improvers mainly) to make a multigrade work as a 10w and an sae 60.
A petroleum based 10w oil requires bucket loads of VI improvers (polymers) which uncoil with temperature increasing the viscosity, unfortunately these polymers are prone to "shear" meaning that the oil stays in grade for less time.
This is the main problem with wide viscosity oils unless they are made with "synthetic" basestocks which require little or no VI improvers to prop them up because they are thermally stable to start with.
The whole point that I'm making is that a 10w-50 or 15w-50 if it's a good oil using decent basestocks is a better bet anyday than a "dino" 10w-60 as it will stay in grade for longer, giving better protection.
You are indeed right about the 5w, 10w protection, believe me a 20w is not much good for your car on chilly mornings!
Cheers
Simon
ClubSport 911
New member
Didn't you argue earlier, that friction modifiers have limited effect on the performance of a car, because friction is a very small component of the losses ? I concurr.
So, why does a heavy oil tend to reduce "performance" ? (whatever that is)...
oilman
New member
The heavier the oil, the more oil drag you get.
It has been proven in tests that you will get more more bhp and torque with thinner oils (see my posts related to these tests done by Silkolene using 15w-50, 5w-40 and 0w-20), the results are below.
Quote:
Must Have MORE Power!
Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power. To get more power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat. For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system. A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25% actually shows up as BHP at the flywheel. 6% goes in pumping air into the engine, 6% as oil drag losses and 2-3% as engine friction. The oil deals with 97% of the friction; so reducing the remaining few percent is not easy. If you doubt that even ordinary oil has a massive effect, take a clean, dry 200 bhp engine, connect it to a dyno and start it up. It will only make 1 bhp for a few seconds. Now that's real friction for you!
Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly "magic additives", which have not the smallest effect on friction but rapidly corrode bearings and wallet contents. In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two bhp or a couple of extra miles per gallon.
Even More Power!
He place to look for extra power is in that 6% lost as oil drag. In a well-designed modern motor, the oil doesn't have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin. How thin? Well take a look at these dyno results.
A while ago now, we ran three Silkolene performance oils in a Honda Blackbird motorcycle. this fearsome device is fitted with a light, compact, naturally aspirated 1100cc engine which turns out 120+ bhp at the back wheel. The normal fill for this one-year-old engine was 15w-50, so the first reading was taken using a fresh sump-fill of this grade. (The dyno was set up for EEC horsepower, i.e. Pessimistic)
15w-50
Max Power 127.9 bhp @ 9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm
After a flush-out and fill up with 5w-40 the readings were;
5w-40
Max Power 131.6 bhp @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm
Then we tried an experimental grade, 0w-20 yes, 0w-20! This wasn't as risky as you may think, because this grade had already done a season's racing with the Kawasaki World Superbike Team, giving them some useful extra power with no reliability problems. (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan)
0w-20
Max Power 134.4 bhp @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm
In other words, 3.7 bhp / 2.9% increase from 15w-50 to 5w-40, a 2.8 bhp / 2.1% increase from 5w-40 to 0w-20 or a 6.5 bhp / 5% overall. Not bad, just for changing the oil! More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust/intake mods, ignition re-mapping etc.
Unquote:
The above only serves as an illustration of what can be achieved with less oil drag.
Cheers
Simon
It has been proven in tests that you will get more more bhp and torque with thinner oils (see my posts related to these tests done by Silkolene using 15w-50, 5w-40 and 0w-20), the results are below.
Quote:
Must Have MORE Power!
Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power. To get more power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat. For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system. A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25% actually shows up as BHP at the flywheel. 6% goes in pumping air into the engine, 6% as oil drag losses and 2-3% as engine friction. The oil deals with 97% of the friction; so reducing the remaining few percent is not easy. If you doubt that even ordinary oil has a massive effect, take a clean, dry 200 bhp engine, connect it to a dyno and start it up. It will only make 1 bhp for a few seconds. Now that's real friction for you!
Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly "magic additives", which have not the smallest effect on friction but rapidly corrode bearings and wallet contents. In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two bhp or a couple of extra miles per gallon.
Even More Power!
He place to look for extra power is in that 6% lost as oil drag. In a well-designed modern motor, the oil doesn't have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin. How thin? Well take a look at these dyno results.
A while ago now, we ran three Silkolene performance oils in a Honda Blackbird motorcycle. this fearsome device is fitted with a light, compact, naturally aspirated 1100cc engine which turns out 120+ bhp at the back wheel. The normal fill for this one-year-old engine was 15w-50, so the first reading was taken using a fresh sump-fill of this grade. (The dyno was set up for EEC horsepower, i.e. Pessimistic)
15w-50
Max Power 127.9 bhp @ 9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm
After a flush-out and fill up with 5w-40 the readings were;
5w-40
Max Power 131.6 bhp @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm
Then we tried an experimental grade, 0w-20 yes, 0w-20! This wasn't as risky as you may think, because this grade had already done a season's racing with the Kawasaki World Superbike Team, giving them some useful extra power with no reliability problems. (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan)
0w-20
Max Power 134.4 bhp @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm
In other words, 3.7 bhp / 2.9% increase from 15w-50 to 5w-40, a 2.8 bhp / 2.1% increase from 5w-40 to 0w-20 or a 6.5 bhp / 5% overall. Not bad, just for changing the oil! More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust/intake mods, ignition re-mapping etc.
Unquote:
The above only serves as an illustration of what can be achieved with less oil drag.
Cheers
Simon
Diver944
Active member
This thread is even more pertinent to me today as it was the day that my S2 got it's half yearly 6000 mile oil change (Castrol 10w40 BTW [] )
Tomorrow I shall be continuing to mop up the mess I made of my driveway.
You'd think I'd make less mess each time as I become more proficient - sadly this is not the case [&:]
] )Tomorrow I shall be continuing to mop up the mess I made of my driveway.
You'd think I'd make less mess each time as I become more proficient - sadly this is not the case [&:]
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