WHICH OIL DO YOU USE?
- Thread starter Guest
- Start date
Be carefull because Mobile 1 and Castrol RS come in 2 different choices of viscosity.
Mobile1 0W40
Mobile1 Motorsport 15W50
Castrol RS 0W40
Castrol RS 10W60
Don't use either of the 0W rated stuff in your track car, but either of the other 2 would be fine. My personal choice is the Castrol, but I don't have a valid argument as to why.
Mobile1 0W40
Mobile1 Motorsport 15W50
Castrol RS 0W40
Castrol RS 10W60
Don't use either of the 0W rated stuff in your track car, but either of the other 2 would be fine. My personal choice is the Castrol, but I don't have a valid argument as to why.
Guest
New member
Only 1 litre which was probably not needed in 10,000 kilometres........the engine always runs very cool and as usual for a good RS is absolutely bone dry (unlike the scare stories of the C2/4 these blueprinted engines are also probably better put together with seals etc...) so in nearly two years not really needed a top up at all.........
0W versus 10W will provide better protection from cold startup and probably better for every day use. The other figure indicates its high end temperature range.
So 0W 40 great for every day use. 10W 60 fantastic for a car that starts up in the paddock and goes no where until warmed up and then thrashes round the track.
The 10W 60 and 15W 50 are not less able to withstand the high temperatures but are indeed better to withstand the high temps. Thats why the 15W 50 Mobil oil is called Mobil 1 Motorsport.
So 0W 40 great for every day use. 10W 60 fantastic for a car that starts up in the paddock and goes no where until warmed up and then thrashes round the track.
The 10W 60 and 15W 50 are not less able to withstand the high temperatures but are indeed better to withstand the high temps. Thats why the 15W 50 Mobil oil is called Mobil 1 Motorsport.
rskiwi
New member
I use Castrol Magnatec and change it twice a year myself. I was advised to use it by a well known specialist it is a great deal cheaper as well. I rang Castrol for advise and they have been testing a (11 engine for years on Magnatec (semi synthetic) with no wear. BTW last time I looked in France, Mobile 1 was a lot cheaper than here and you need 3 cans so it is worth picking up on your next trip!
My recent trip to Le Mans the RS used about 1/3 of litre 800 miles.
Jeff
My recent trip to Le Mans the RS used about 1/3 of litre 800 miles.
Jeff
Maurice
as I am sure you are aware Porsche produces a list of approved oils and that such a list requires considerable expenditure on Porsche's part to produce. Porsche Cannot possibly approve or test all oil companies products or grades. What they tend to do instead is carry an approvals list of certain makes and grades that are in general use in Porsches current model line up. For instance Porsche have tied up with mobil and use this as "factory" fill on new cars. And consequently Mobil features strongly on the approvals list.
When the 964 RS was new Porsche had close links with Shell (they were title sponsors for Carrera cup) And Shell oils were the factory approved oils of the time. I bet you won't find to many Shell oils on the approved list now.
Both the Castrol RS and Mobil 1 motorsport oils claim to be fully synthetic (it's emblazened on the package on both oils).
Race engines tend towards tight tolerances not loose ones. Well winning ones do anyway. The decision to go with the 0W or higher grades is a personal thing for most people. The differance is probably minimal and very difficult to prove or check without a full r&d team on your side. But it is possible to generalise a little. The zero winter grades will be better at providing good cold start protection in cold weather when the zero viscocity rating will have some effect. Overall they will be a thinner oil at lower temperatures. For older or higher mileage engines which have increased tolerances due to wear and tear it will be "in theory" easier for a thinner oil to bypass oil control sytems (such as old seals etc) notice I say in theory!
The motorsport oils are less concerned with cold start protection and are designed for the rigours of motor sport use (such as sustained high revs and "abuse") without regard for viscosity, they contain (or at least should if you belive the "motorsport" tag) additives or blends that are tailored for their use. As most 964RS spend a lot of time on track and a lot less time being started up in the winter it's likely that most will choose the motorsport branded oils.
as I am sure you are aware Porsche produces a list of approved oils and that such a list requires considerable expenditure on Porsche's part to produce. Porsche Cannot possibly approve or test all oil companies products or grades. What they tend to do instead is carry an approvals list of certain makes and grades that are in general use in Porsches current model line up. For instance Porsche have tied up with mobil and use this as "factory" fill on new cars. And consequently Mobil features strongly on the approvals list.
When the 964 RS was new Porsche had close links with Shell (they were title sponsors for Carrera cup) And Shell oils were the factory approved oils of the time. I bet you won't find to many Shell oils on the approved list now.
Both the Castrol RS and Mobil 1 motorsport oils claim to be fully synthetic (it's emblazened on the package on both oils).
Race engines tend towards tight tolerances not loose ones. Well winning ones do anyway. The decision to go with the 0W or higher grades is a personal thing for most people. The differance is probably minimal and very difficult to prove or check without a full r&d team on your side. But it is possible to generalise a little. The zero winter grades will be better at providing good cold start protection in cold weather when the zero viscocity rating will have some effect. Overall they will be a thinner oil at lower temperatures. For older or higher mileage engines which have increased tolerances due to wear and tear it will be "in theory" easier for a thinner oil to bypass oil control sytems (such as old seals etc) notice I say in theory!
The motorsport oils are less concerned with cold start protection and are designed for the rigours of motor sport use (such as sustained high revs and "abuse") without regard for viscosity, they contain (or at least should if you belive the "motorsport" tag) additives or blends that are tailored for their use. As most 964RS spend a lot of time on track and a lot less time being started up in the winter it's likely that most will choose the motorsport branded oils.
oilman
New member
Another interesting oil thread here. I have a couple of points to make.
Firstly, I think you'll find that Castrol 10w-60 is Porsche Approved anymore (since 1990) as Porsche have been recommended lower viscocity oils for a few years now.
The market is moving to thinner oils because of emmissions, fuel economy and power delivery.
Secondly, a thinner more "shear stable" oil (true synthetic) will outperform a thicker MC/HC oil every time as it remains in grade without thinning for longer periods.
Thirdly, better oils today are generally ones with narrower viscosities, by this I mean 5w-40 as opposed to 10w-60. The reasons for this is because wide viscosity oils (10w-60 for example) unless made of shear stable basestocks such as PAO or Esters need propping up with loads of VI Improvers which make them more prone to "shearing" with use. For example an oil may be a 10w-60 when hot on day one but will "shear" to a 10w-30 within a couple of thousand miles - It's the use that sorts them out.
Finally, a thick oil will give you good oil pressure but, pressure is a measure of resistance not flow and oil flow is more important.
Here is some reading in case I haven't explained myself clearly:
TRUE SYNTHETICS ARE MORE "SHEAR STABLE"
SAE has a test called HT/HS (High Temperature/High Shear).
The higher the HT/HS number the better because this indicates less shearing. Petroleum based oils tend to have low HT/HS numbers which barely meet the standards set by SAE. Because petroleum based oils are made with light weight basestocks to begin with, they tend to burn off easily in high temperature conditions which causes deposit formation and oil consumption.
As a result of excessive oil burning and susceptibility to shearing (as well as other factors) petroleum based oils must be changed more frequently than synthetics.
Not all multi-viscosity oils shear back so easily. True synthetic oils (PAO's and Esters) contain basically no waxy contamination to cause crystallization and oil thickening at cold temperatures. In addition, synthetic basestocks do not thin out very much as temperatures increase. So, pour point depressants are unnecessary and higher viscosity basestock fluids can be used which will still meet the "W" requirements for pumpability.
Hence, little or no VI improver additive would need to be used to meet the sae 30, 40 or 50 classification while still meeting 0W or 5W requirements.
The end result is that very little shearing occurs within true synthetic oils because they are not "propped up" with viscosity index improvers. There simply is no place to shear back to. In fact, this is easy to prove by just comparing synthetic and petroleum based oils of the same grade.
Synthetics will generally have significantly higher HT/HS numbers. Of course, the obvious result is that your oil remains "in grade" for a much longer period of time for better engine protection and longer oil life.
A BIT ABOUT VI IMPROVERS.
As a lubricant basestock is subjected to increasing temperatures it tends to lose its viscosity. In other words, it thins out. This leads to decreased engine protection and a higher likelihood of metal to metal contact. Therefore, if this viscosity loss can be minimized, the probability of unnecessary engine wear will be reduced.
VI improvers are polymers that expand and contract with changes in temperature. At low temperatures they are very compact and affect the viscosity of a lubricant very little. But, at high temperatures these polymers "expand" into much larger long-chain polymers which significantly increase the viscosity of their host lubricant.
So, as the basestock loses viscosity with increases in temperature, VI improvers "fight back"
against the viscosity drop by increasing their size. The higher the molecular weight of the polymers used, the better the power of "thickening" within the lubricant. Unfortunately, an increase in molecular weight also leads to an inherent instability of the polymers themselves. They become much more prone to shearing within an engine.
As these polymers are sheared back to lower molecular weight molecules, their effectiveness as a VI improver decreases. Unfortunately, because petroleum basestocks are so prone to viscosity loss at high temperatures, high molecular weight polymers must be used. Since these polymers are more prone to shearing than lower molecular weight polymers, petroleum oils tend to shear back very quickly. In other words, they lose their ability to maintain their viscosity at high temperatures.
Synthetic basestocks, on the other hand, are much less prone to viscosity loss at high temperatures. Therefore, lower molecular weight polymers may be used as VI improvers.
These polymers are less prone to shearing, so they are effective for a much longer period of time than the VI improvers used in petroleum oils. In other words, synthetic oils do not quickly lose their ability to maintain viscosity at high temperatures as petroleum based oils do.
Some synthetic basestocks are so stable at high temperatures they need NO VI improvers at all. Obviously, these basestocks will maintain their high temperature viscosities for a very long time since there are no VI improvers to break down.
Hope this helps
Cheers
Simon
Firstly, I think you'll find that Castrol 10w-60 is Porsche Approved anymore (since 1990) as Porsche have been recommended lower viscocity oils for a few years now.
The market is moving to thinner oils because of emmissions, fuel economy and power delivery.
Secondly, a thinner more "shear stable" oil (true synthetic) will outperform a thicker MC/HC oil every time as it remains in grade without thinning for longer periods.
Thirdly, better oils today are generally ones with narrower viscosities, by this I mean 5w-40 as opposed to 10w-60. The reasons for this is because wide viscosity oils (10w-60 for example) unless made of shear stable basestocks such as PAO or Esters need propping up with loads of VI Improvers which make them more prone to "shearing" with use. For example an oil may be a 10w-60 when hot on day one but will "shear" to a 10w-30 within a couple of thousand miles - It's the use that sorts them out.
Finally, a thick oil will give you good oil pressure but, pressure is a measure of resistance not flow and oil flow is more important.
Here is some reading in case I haven't explained myself clearly:
TRUE SYNTHETICS ARE MORE "SHEAR STABLE"
SAE has a test called HT/HS (High Temperature/High Shear).
The higher the HT/HS number the better because this indicates less shearing. Petroleum based oils tend to have low HT/HS numbers which barely meet the standards set by SAE. Because petroleum based oils are made with light weight basestocks to begin with, they tend to burn off easily in high temperature conditions which causes deposit formation and oil consumption.
As a result of excessive oil burning and susceptibility to shearing (as well as other factors) petroleum based oils must be changed more frequently than synthetics.
Not all multi-viscosity oils shear back so easily. True synthetic oils (PAO's and Esters) contain basically no waxy contamination to cause crystallization and oil thickening at cold temperatures. In addition, synthetic basestocks do not thin out very much as temperatures increase. So, pour point depressants are unnecessary and higher viscosity basestock fluids can be used which will still meet the "W" requirements for pumpability.
Hence, little or no VI improver additive would need to be used to meet the sae 30, 40 or 50 classification while still meeting 0W or 5W requirements.
The end result is that very little shearing occurs within true synthetic oils because they are not "propped up" with viscosity index improvers. There simply is no place to shear back to. In fact, this is easy to prove by just comparing synthetic and petroleum based oils of the same grade.
Synthetics will generally have significantly higher HT/HS numbers. Of course, the obvious result is that your oil remains "in grade" for a much longer period of time for better engine protection and longer oil life.
A BIT ABOUT VI IMPROVERS.
As a lubricant basestock is subjected to increasing temperatures it tends to lose its viscosity. In other words, it thins out. This leads to decreased engine protection and a higher likelihood of metal to metal contact. Therefore, if this viscosity loss can be minimized, the probability of unnecessary engine wear will be reduced.
VI improvers are polymers that expand and contract with changes in temperature. At low temperatures they are very compact and affect the viscosity of a lubricant very little. But, at high temperatures these polymers "expand" into much larger long-chain polymers which significantly increase the viscosity of their host lubricant.
So, as the basestock loses viscosity with increases in temperature, VI improvers "fight back"
against the viscosity drop by increasing their size. The higher the molecular weight of the polymers used, the better the power of "thickening" within the lubricant. Unfortunately, an increase in molecular weight also leads to an inherent instability of the polymers themselves. They become much more prone to shearing within an engine.
As these polymers are sheared back to lower molecular weight molecules, their effectiveness as a VI improver decreases. Unfortunately, because petroleum basestocks are so prone to viscosity loss at high temperatures, high molecular weight polymers must be used. Since these polymers are more prone to shearing than lower molecular weight polymers, petroleum oils tend to shear back very quickly. In other words, they lose their ability to maintain their viscosity at high temperatures.
Synthetic basestocks, on the other hand, are much less prone to viscosity loss at high temperatures. Therefore, lower molecular weight polymers may be used as VI improvers.
These polymers are less prone to shearing, so they are effective for a much longer period of time than the VI improvers used in petroleum oils. In other words, synthetic oils do not quickly lose their ability to maintain viscosity at high temperatures as petroleum based oils do.
Some synthetic basestocks are so stable at high temperatures they need NO VI improvers at all. Obviously, these basestocks will maintain their high temperature viscosities for a very long time since there are no VI improvers to break down.
Hope this helps
Cheers
Simon
oilman
New member
I don't think there is any justification for using an oil thicker than 10w-50 or possibly 15w-50 so long as the 50 is a "true" synthetic even then this thickness may be "overkill" for many engines. 10w-50 would be my preference for better cold start protection as well.
Cheers
Simon
Cheers
Simon
Diver944
Active member
ORIGINAL: oilman
You could always email us, we're full of nice surprises[]
Guys I received a pricelist from Simon a few weeks ago and I am very pleased with his prices for club members [
]For example Mobil 1 0w40 for £27.49 (or 4 packs for £102.49), Mobil1 Motorsport 15w50 for £26.49 (or 4 packs for £102.49) and Castrol RS 10w60 for £25.49 (or 4 packs for £98.49)
One fully synthetic brand I have noticed is Silkolene Pro S 10w50 in 5 litre packs for £27.99 or 25 litres for £108.99 and this is listed as having Porsche approval
I think if you had a nice advert in Porsche Post with some of these prices you woud get a lot of orders from the general membership (there are only very few of us who regularly use the forum)
oilman
New member
Maurice,
There seem to be a number of things here that contribute to this situation regarding approvals.
Approvals are renewed every few years and they cost the oil Companies a lot of money, as much as £200,000 a product with some OEM's so oil manufacturers usually seek approval on limited products, relying on API and ACEA approvals to meet specs.
I believe that like all major OEM's (VAG, MB, BMW, FORD, HONDA, GM etc) the market is moving toward thinner oils 0w, 5w etc and Porsche is no exception so the cost of seeking approval or reapproval of 10w and 15w oils is commercially not a viable proposition.
This doesn't mean that these oils are not suitable for your car, they're just not approved by Porsche and therefore during the warranty period it would not be wise to use them if you want to keep it in tact.
In some cases, Oil Companies work with the OEM's to develop specific oils for their cars at factory fill level and these days the oils developed remain the spec for the life of the car. One good example of this is Fuchs in Germany who work with BMW, VAG, MB and with Porsche to develop the next generation of oils for your car.
There are a good number of Porsche Approved oils on the market, I sell a number and the grades are quite wide ranging
0w-30
0w-40
5w-40
5w-50
10w-50
However, none of my 10w-60's or 15w-50's carry the Porsche Approvals.
Hope this helps
Cheers
Simon
There seem to be a number of things here that contribute to this situation regarding approvals.
Approvals are renewed every few years and they cost the oil Companies a lot of money, as much as £200,000 a product with some OEM's so oil manufacturers usually seek approval on limited products, relying on API and ACEA approvals to meet specs.
I believe that like all major OEM's (VAG, MB, BMW, FORD, HONDA, GM etc) the market is moving toward thinner oils 0w, 5w etc and Porsche is no exception so the cost of seeking approval or reapproval of 10w and 15w oils is commercially not a viable proposition.
This doesn't mean that these oils are not suitable for your car, they're just not approved by Porsche and therefore during the warranty period it would not be wise to use them if you want to keep it in tact.
In some cases, Oil Companies work with the OEM's to develop specific oils for their cars at factory fill level and these days the oils developed remain the spec for the life of the car. One good example of this is Fuchs in Germany who work with BMW, VAG, MB and with Porsche to develop the next generation of oils for your car.
There are a good number of Porsche Approved oils on the market, I sell a number and the grades are quite wide ranging
0w-30
0w-40
5w-40
5w-50
10w-50
However, none of my 10w-60's or 15w-50's carry the Porsche Approvals.
Hope this helps
Cheers
Simon
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