Which Engine Oil
- Thread starter DavidM777
- Start date
964rsdatabase
New member
Used to use Mobil 1 a few years ago, then the garage changed it to Castrol Magnatec for a couple of years. Just recently changed to a different garage and they have just replaced it for Castrol RS. The new stuff has my vote as it smells fantastic!
Basically, as long as you change it frequently enough (mine is done every year, which is about 1500 miles) i don't think it matters. Maybe too often if that's possible.
Martin
Basically, as long as you change it frequently enough (mine is done every year, which is about 1500 miles) i don't think it matters. Maybe too often if that's possible.
Martin
964rh
New member
I was recommended the Silkolene Pro s stuff. Fairly cheap as well from the oilman
No issues that I'm aware of, I don't get the small leak after a few laps that I did with the castrol RS. Not sure whether that good or bad[&:]
I know of a few others using in a 64RS.
Smells nice when burnt not sure on the taste but I'll give it a go after the Rugby on Sat.[
]
No issues that I'm aware of, I don't get the small leak after a few laps that I did with the castrol RS. Not sure whether that good or bad[&:]
I know of a few others using in a 64RS.
Smells nice when burnt not sure on the taste but I'll give it a go after the Rugby on Sat.[
]
Mobil 1 motorsport for me too. Buy it in france or anywhere but the uk as it's ridiculously expensive here.
sawood12
New member
Why Mobil 1? Sure it is a very good oil but there are many more out there that are far more technologically advanced and therefore superior. Mobil 1 is a pretty basic, albeit very good, fully synthetic oil. Silkolene Pro S is one such oil. It is an Ester oil so is clingy like Magnatec. As long as you use a fully synthetic oil and are not doing anything out of the ordinary regarding your driving, like racing (though track days should be OK), then you should be fine on any good quality fully synthetic. Semi Synthetics are a con. They have so little 'synthetic' content you should consider them to be mineral oils.
When it comes to oil my philosophy is get the best you can. Even an expensive oil is relatively cheap compared to other maintenance costs you're usually happy to pay for and it is afterall the life blood of your engine. As for oils that are supposed to be for 'older engines', well I personally wouldn't take much notice of the marketting hype. How can an oil be engineered for older engines? How would it differ from any other oil of the same grade?
When it comes to oil my philosophy is get the best you can. Even an expensive oil is relatively cheap compared to other maintenance costs you're usually happy to pay for and it is afterall the life blood of your engine. As for oils that are supposed to be for 'older engines', well I personally wouldn't take much notice of the marketting hype. How can an oil be engineered for older engines? How would it differ from any other oil of the same grade?
i asked this question here a while back,got plenty of replies most were silkolene,so i have put in pro s 10-50 which i think would be best all round for road and track use, i was going to put 15-50 mobil in but most reckon silkolene is far better oil than mobil, it is alot cheaper, mine engine is very dry and very quiet and heats up just as quick as 10-40 magnatec...which was recomended by specialist,my engine was tappety with magnatec, and is way too cheap to be any good
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ubertub
New member
I spent a small fortune on 11.5 litres of fully-synthetic Motul Racing 4T only to have 9Meister throw it in the bin with zero miles on it!!! When I went hairless Robin kindly explained the 964 type motor is basically a '60s design and modern synthetic/ semi oils do not have the detergents these engines require. Why spend a lot of cash on unsuitable oil. It made sense to me. I use 10w40 or 15w50 in summer and winter but don't bother with fully-synth at all. I imagine 9M know a thing or two about building engines... at least more than I do.
SimonExtreme
New member
I don't think I have ever disagreed with anything said by anybody at (M but I sugest you do a search on cleaning ability of and detergents in of synthetic oils. I can only assume that there has been a misunderstand on this one. Synthetics are just as good at "cleaning" and are probably slightly better at holding contaminates in suspension, although most agree not enough better to enable longer intervals between changes.
The only oils I know of without detergent are single SAE and shouldn't be used in cars.
Having said that, our engines seem to do pretty well without really flash oils. Yes, in theory the Silkolene which I used to use should give the best protection, but I doubt you could measure that better protection compared with Mobil 1.
Hi - I think you need to seperate the viscocity from the type of oil. A 10-40 Synthentic has exactly the same viscocity as a 10-40 semi / non synthetic, so the viscocity of any type oil used should match Porsches recommendations.
Modern oils have better detergent and additive packages, again whether they are synthetic or non synthetic. The advantages of synthetic oil are that the molecules are "man made" for the job, and all exactly the same, as opposed to oil derived directly from mineral sources, where the base oil can be made from molecules of differing sizes and properties. This causes mineral oil to break down sooner under shear and heat, and for the oil to start losing it's essential properties.
I would imagine that if you are changing your oil very regularly, then either type would be OK, but for a road car with long change periods, the synthetic will keep it's lubricating properties at a peak for much longer than a semi / non synthetic. If you are doing regular track days, where the engine operates for long periods at high revs, and generates high heat output, then a synthetic oil is also the one to go for.
Pete
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sawood12
New member
Fully synthetic oils are not man-made are they? Surely they are still based on mineral oils but have undergone some form of processing.
It is a good point about the longevity of fully synths and their resistance to chemical breakdown. Especially on cars that are used infrequently.
It is a good point about the longevity of fully synths and their resistance to chemical breakdown. Especially on cars that are used infrequently.
Made from various chemical compounds, some of which may originally have been extracted from crude oil, but not from modified oil itself - real designer stuff [
]It means you can produce an oil which is much closer to the ideal than if you were just working from crude oil
This is from Wikipedia: http://en.wikipedia.org/wiki/Synthetic_oil
Synthetic oil is oil consisting of chemical compounds which were not originally present in crude oil (petroleum) but were artificially made (synthesized) from other compounds. Synthetic oil could be made to be a substitute for petroleum or specially made to be a substitute for a lubricant oil such as conventional (or mineral) motor oil refined from petroleum.
The longevity I was referring to was more their stability and resistance to break down in high stress situations eg long periods at high engine revs, and in extremes of heat (turbo's etc)
Pete
metric_thumbs
New member
How does an oil break down under stress?
Are you suggesting that in a bearing there are enough stresses and great enough strain to break inter molecular bonds?
One hears often about oil break down - but I have never seen an explanation of the mechanism of the breakdown. I would be grateful for any help in understanding this.
Furthermore what is the effect and affect of this breakdown, does the oil loose viscosity or cohesion or 'slipperyness'?
As someone who has been usually lax in changing oil in a variety of classic cars, some of them real screamers, I have never noticied any adverse wear conditions caused by my laziness.
smallspeed
New member
there is some shear at work however oil breaks down in car engines mostly due to heat; the oil pressure in a car engine is piddly and the running clearances of most components (excluding bearing surfaces) are not tight enough so not really capable of creating high shear. When an oil does break down under shear its usualy around cam shafts/followers/valve tips or oil pumps. The shear occurs at an inter molecular level, and yes, the point contact shear stress in areas like valve stems do get that high..
The heat causes oil to breakdown by burning off different parts of the base stock which results in black sludge/carbon buildup within the oil. The higher the flashpoint of the oil the higher temperature it can withstand or the longer it will last at a given temperature. Synthetic oils are engineered to have higher flashpoints, therefore reducing the rate of burn-off/breakdown and sludge build up. Synthetic oils use an engineered base-stock as mentioned earlier in the thread (engineered from organic oil components and sometimes just a mineral oil with certain elements removed or reduced, or some form of chemical processing). An additive package will then be added to give the required characteristics. A semi synthetic oil is typically the same (or similar) additive package in a natural base oil.
Multigrade oils have polymers added to a base (usually a light weight in the region 0W - 20W). The purpose of these polymers is to prevent the oil from thinning too much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as if just the basestock was in use. As the oil warms up the polymers stretch into long chains that effectively thicken the oil even though the base stock element in isolation is thin. In small running clearance components and even in an oil pump these polymer chains get chopped up, causing a degridation in the multigrade element.. Now the chains are shorter hence can thicken the oil to a lesser degree.. Your 10W-50 (which previously worked as a 10W basestock oil at 0-deg and a 50W oil at 100-deg) now behaves like a 30 or 20W oil at 100-deg.. This is very important in an air cooled engine as the heat capacity of the oil really starts to play a part in the cooling of the engine; once the heat capacity is reduced, the cooling effect of the oil is reduced and engine temperatures increase.. This is then a viscious cycle; the increased temperatures cause increased break-down rates of the oil and additives..
Another thing which breaks down (again mostly due to heat) is the additive package, which is very important. This prevents rust (pure oil will not prevent rust), cleans components, helps with suspension of particulates, modifies friction, etc. This additive package is very important for protection of the internals of the engine; once this starts to break down the running friction of parts can increase, deposits form, etc.
One of the most important functions of the oil (and often overlooked) is the ability to remove particulates and take them to the filter (whcih is designed to entrap them). There is a limit of how much particulate weight can be suspended in the oil, and once this is exceded deposits will start to be formed around the engine which can cause long term damage and wear. This suspension limit will degrade also over time due to heat, and so your oils ability to flush the engine decreases; this is usually engineered into the additive package..
Interestingly (or perhaps not) hydraulic systems (my line of work) tend to have frequent filter changes (every couple of hundred hours), however only change the oil every couple of thousand hours.. The oil flushes the system clean and then the filter cleans the oil to the point where the oil which has been in the system for 4 or 500 hrs is cleaner than new oil.. This doesnt work so well in engines due to the carbon build-up and exposure to higher temperatures... Hydraulic systems tend not (although it is becoming increasingly more common) to use multigrade oils either due to the high pressures involved and close running tolerances of pumps, valves and motors which would reduce the life of the multigrade element considerably..
There are many other factors in degredation of engine oil, and Im no expert so im going to stop before either I or you fall asleep..
but to answer the original question.. I use Mobil 1 15W50 and hang the price... its what Porsche, our oil supplier and my specialist recommended, and thats good enough for me []
The heat causes oil to breakdown by burning off different parts of the base stock which results in black sludge/carbon buildup within the oil. The higher the flashpoint of the oil the higher temperature it can withstand or the longer it will last at a given temperature. Synthetic oils are engineered to have higher flashpoints, therefore reducing the rate of burn-off/breakdown and sludge build up. Synthetic oils use an engineered base-stock as mentioned earlier in the thread (engineered from organic oil components and sometimes just a mineral oil with certain elements removed or reduced, or some form of chemical processing). An additive package will then be added to give the required characteristics. A semi synthetic oil is typically the same (or similar) additive package in a natural base oil.
Multigrade oils have polymers added to a base (usually a light weight in the region 0W - 20W). The purpose of these polymers is to prevent the oil from thinning too much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as if just the basestock was in use. As the oil warms up the polymers stretch into long chains that effectively thicken the oil even though the base stock element in isolation is thin. In small running clearance components and even in an oil pump these polymer chains get chopped up, causing a degridation in the multigrade element.. Now the chains are shorter hence can thicken the oil to a lesser degree.. Your 10W-50 (which previously worked as a 10W basestock oil at 0-deg and a 50W oil at 100-deg) now behaves like a 30 or 20W oil at 100-deg.. This is very important in an air cooled engine as the heat capacity of the oil really starts to play a part in the cooling of the engine; once the heat capacity is reduced, the cooling effect of the oil is reduced and engine temperatures increase.. This is then a viscious cycle; the increased temperatures cause increased break-down rates of the oil and additives..
Another thing which breaks down (again mostly due to heat) is the additive package, which is very important. This prevents rust (pure oil will not prevent rust), cleans components, helps with suspension of particulates, modifies friction, etc. This additive package is very important for protection of the internals of the engine; once this starts to break down the running friction of parts can increase, deposits form, etc.
One of the most important functions of the oil (and often overlooked) is the ability to remove particulates and take them to the filter (whcih is designed to entrap them). There is a limit of how much particulate weight can be suspended in the oil, and once this is exceded deposits will start to be formed around the engine which can cause long term damage and wear. This suspension limit will degrade also over time due to heat, and so your oils ability to flush the engine decreases; this is usually engineered into the additive package..
Interestingly (or perhaps not) hydraulic systems (my line of work) tend to have frequent filter changes (every couple of hundred hours), however only change the oil every couple of thousand hours.. The oil flushes the system clean and then the filter cleans the oil to the point where the oil which has been in the system for 4 or 500 hrs is cleaner than new oil.. This doesnt work so well in engines due to the carbon build-up and exposure to higher temperatures... Hydraulic systems tend not (although it is becoming increasingly more common) to use multigrade oils either due to the high pressures involved and close running tolerances of pumps, valves and motors which would reduce the life of the multigrade element considerably..
There are many other factors in degredation of engine oil, and Im no expert so im going to stop before either I or you fall asleep..
but to answer the original question.. I use Mobil 1 15W50 and hang the price... its what Porsche, our oil supplier and my specialist recommended, and thats good enough for me [
]
What smallspeed said [
]With regard to adverse wear conditions, I think you can only judge over a long period of time - this is one of my beefs with Independents recommending semi synthetics ( can contain a minimum of 30% synthetic base stock....) What are they basing their judgements on? - how many of them are that familiar with a specific vehicle over the period of time required to judged the differences.
The cams on my engine were worn out after 113,000 miles, and the engine needed a £6000 rebuild (before I bought it [
]) who knows what oil was used by the 4 different Independents that serviced it, and whether it contributed to the wear. Porsche recommend synthetic oils almost exclusively, there is enough non marketing flim flam related evidence that they are better, so that is what I use, even though my indy says "we've never had any problems" [
]Pete
metric_thumbs
New member
Thanks you two
I agree the only place there is sufficient shear at a high enough rate for any oil distress is at cam tips on solid lifters. Some shaped lifters and roller lifters avoid the high shear by clever design. I agree the wrong oil can exacerbate this sliding wear, and as oils are 'impoved' for modern engines they are loosing a lot of the additives which helped cam follower wear.
Some racing oils and 'break in oils' have a lot of these old additives which can remove any reasonable follower wear.
Also motorcycle oils are good as they have to endure a hard life inside a Japanese multicylinder.
I find Simon at http://www.opieoils.co.uk is a good source to discuss oil types
I agree the only place there is sufficient shear at a high enough rate for any oil distress is at cam tips on solid lifters. Some shaped lifters and roller lifters avoid the high shear by clever design. I agree the wrong oil can exacerbate this sliding wear, and as oils are 'impoved' for modern engines they are loosing a lot of the additives which helped cam follower wear.
Some racing oils and 'break in oils' have a lot of these old additives which can remove any reasonable follower wear.
Also motorcycle oils are good as they have to endure a hard life inside a Japanese multicylinder.
I find Simon at http://www.opieoils.co.uk is a good source to discuss oil types
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