Engine Oil - 2.7 - what do you use

944 man · Jun 8, 2009

ORIGINAL: sawood12
I'm pretty sure you can get fully synths in pretty much any multi grade combo you need can't you? You can get 0W through to 20W and 30 through to 60 and any combination of the two sets. You can also get fully synthetic single grade oils for race purposes and other specialist purposes.

You can. Unfortunately theyre far more common/popular in 0W- and 5W- gardes and its these unsuitable grades which are recommended, frequently by the oil manufacturers... Mobil being a good example of a company recommending a wholly unsuitable oil, which suits them (0W- in a 924S ffs!).

Simon

333pg333 · Jun 8, 2009

Scott, the idea that a thinner oil is going to offer you more protection than a thicker one based on wiping the bottom of a porridge bowl with your finger is categorically wrong....however scientific. [

] I'm not sure if you've read either article I posted links to, but there is a lot of 'in the field info' there.
As for no engine failures due to the wrong oil, well I know of plenty. Many of the failed #2 rod bearings could be put down to this. Obviously there is an inherent design fault too, but many of these were using M1 5w/40 or similar oil. The thicker oils actually act as the 'bearing' when under stress. As the oils heat up, especially on the track, they get thinner and don't offer enough protection when metal parts are trying to smash into each other.
I'm very happy to sacrifice a small bit of petrol mileage by using a suitable oil. Also when using a thicker oil it does leave a film up top for cold start as opposed to the fuel economy oils that leave the cam etc almost dry after periods of inactivity. This has been witnessed in the workshop of Bruce Buchanan, the Aussie mechanic in the 2nd link.

Copperman05 · Jun 9, 2009

As for low grade synthetic oils not being suitable here is what my 944 manual says.

Firstly the manual lists the different oils to use at differing temps, it lists single grade oils (Listing SAE 30,40), Multigrade oils (listing SAE 20W-40 - 15W-40 - 5W-20, etc) and Fuel Economy Oils (Listing SAE 10W-30 5W-40 and 5W-50 for temp range from -30 to +40C)

Then later on the same page in the text headed 'Fuel Economy Oils' it says;

'Fuel economy oils require low viscosity at low temperature and high thermal stability at high temperatures. As high-performance oils, these oils are manufactured only as synthetic or hydrocrack oils at present. On account of their low viscosity, these oils are also fuel economy oils and are termed "all season fuel economy oils" in the Porsche Approval.'

So it appears that synthetic oil was recommended in my Porsche 944/944 Turbo manual (May 1988) and it is clear to me that Porsche approved this so called all season fuel economy oil (due to its large viscosity range and improved fuel economy), that is also states was only available as a synthetic or hyrocrack oil.

So far from being unsuitable it would seem that synthetic oils, including those in the 5w-40, 5w-50 range are suitable for the 944 engine and were actually approved by Porsche.
[

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Edd

333pg333 · Jun 9, 2009

Fuel economy oils and Porsche Turbo are not what I'd call good bedfellows. If you want fuel economy and drive sedately, why buy a Porsche Turbo??
I say this respectfully knowing how much you guys are robbed when filling your tanks, but really.....Heck you can put 0w/30 in there if you like and perambulate Miss Daisy down to the village to pick up her Sherry......but if you drive the car how it was designed for then these oils could easily see you with some expensive repairs ahead. Best of luck.
BTW there is no such thing as a fully synthetic oil used in cars. They all come from a base stock of mineral oil.

Copperman05 · Jun 9, 2009

ORIGINAL: 333pg333

Fuel economy oils and Porsche Turbo are not what I'd call good bedfellows. If you want fuel economy and drive sedately, why buy a Porsche Turbo??
I say this respectfully knowing how much you guys are robbed when filling your tanks, but really.....Heck you can put 0w/30 in there if you like and perambulate Miss Daisy down to the village to pick up her Sherry......but if you drive the car how it was designed for then these oils could easily see you with some expensive repairs ahead. Best of luck.
BTW there is no such thing as a fully synthetic oil used in cars. They all come from a base stock of mineral oil.

I think you are missing the point here slightly, no one is saying they bought a porsche 944 Turbo for good fuel economy. The manual is simply stating that if you use a good synthetic oil such as 5W-40 the low viscosity reduces drag on the engine and therefore improves fuel economy. I think any efforts to be more fuel efficient are worthy whatever size or type of car you drive.

At the same time the manual is stating that low vicosity synthetic oils are suitable and recommended for the 944 which seems is the opposite to what some are purporting to be the case.

944 man · Jun 9, 2009

As far as I recall: and as far as I can see now, Porsche only 'recommends' 5W- oils where the vehicle is being operated in enviroments which reach -30c and never even approach freezing.

Copperman05 · Jun 9, 2009

Porsche recommends in the manual to use 5W-40 and 5W-50 in the temperature range -30 - +40 (the whole of the temperature bar at the top of the graph).

I can provide a scan of the manual if this would help...

Edd

944 man · Jun 9, 2009

In my manual the fuel efficient oils are 10W-. Empirical evidence still suggests that these oils dont suit the cars and even if they did then, they are far from ideal now.

Simon

333pg333 · Jun 9, 2009

Here you go.

Notice that they put these oils in their own little section titled Fuel Economy Oils. Nobody wanted to use them much in reality, but you could use them though they're not ideal. I know I won't convince many who want to use these oils. Luckily we live in a free part of the world. All I can say is that you and I might theorise, whereas people like Bruce Buchanan is a Porsche factory trained mechanic and was close friends with Klauss Kessner (sp) who was one of the Porsche engineers. Neither has any doubts over the matter. You will open your engine up to the possibility of increased wear or worse by using some of these oils. Even the ones that the Porsche factory recommended.

Copperman05 · Jun 9, 2009

ORIGINAL: 944 man

In my manual the fuel efficient oils are 10W-. Empirical evidence still suggests that these oils dont suit the cars and even if they did then, they are far from ideal now.

Simon

Surely they were ideal then and they are ideal now, the lower the viscosity oil at lower temp the better, better for cold starts when most damage occurs, better for fuel economy. Unless you have a particularly high mileage car where the highmilage oils maybe more appropriate I cant see why the oils such as those recommended by porsche in including 5W-40 synthetic shouldnt be used and in fact offer the best all year round performance, fuel economy and engine longevitiy.

Edd

Copperman05 · Jun 9, 2009

This graph is Porsche Recommeded oils, and yes they ARE ALL ideal as that is why porsche is recommending them. They have there own little section because they are high performance synthetic oils (porsches words not mine) and have a high temperature range that enables them to be used in all seasons. They are also more fuel efficient due to less drag on the engine.

Read the text under 'Fuel Economy Oils'

Hilux · Jun 9, 2009

Says it all really.

In our climate with our average temps Porsche specified 15w and 20W generally.

0` 5`s and 10`s are for Russia in the winter as the low numbers are due to extreme cold so thin oils are only needed for startup protection in cold climates and will run off the engine parts and wont offer the bulk protection on start up of higher numbered oils in warm climes.

This will also be true of higher tolerances/gaps as the engine wears (as I keep saying) [

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Copperman05 · Jun 9, 2009

I think perhaps it appears slightly confusing for some the way porsche has listed the wide viscosity range oils as 'Fuel Economy Oils', replace 'Fuel Economy Oils' with 'Synthetic Oils' (as stated on the same page that this is what Fuel economy oils are) on the graph and it reads somewhat differently.

Edd

Eric_Oz_S2 · Jun 9, 2009

I run Mobil 1 5W50 here in Australia in an S2 - it never gets below about 10 degrees, but often gets above 30-35. 10W40 is useless for track work.

Neil Haughey · Jun 9, 2009

I agree with Eric, look the thing is living down South we practically never see -10c yet I have had many days in recent years sat in the car with ambient temps in the mid 30's, a few years back we had weeks on end up in the 30's, I remember it well because one day I lost 2 litres of body fluids, sweating like mad, and promised myself after that to get aircon. To be quite honest I would much rather have a car that is a bit slow to crank on a cold start then risk oil shear when its hot, and that is not even starting to consider the fact that you need thicker oils in engines with high mileages.

sawood12 · Jun 9, 2009

ORIGINAL: 333pg333

Scott, the idea that a thinner oil is going to offer you more protection than a thicker one based on wiping the bottom of a porridge bowl with your finger is categorically wrong....however scientific. [] I'm not sure if you've read either article I posted links to, but there is a lot of 'in the field info' there.
As for no engine failures due to the wrong oil, well I know of plenty. Many of the failed #2 rod bearings could be put down to this. Obviously there is an inherent design fault too, but many of these were using M1 5w/40 or similar oil. The thicker oils actually act as the 'bearing' when under stress. As the oils heat up, especially on the track, they get thinner and don't offer enough protection when metal parts are trying to smash into each other.
I'm very happy to sacrifice a small bit of petrol mileage by using a suitable oil. Also when using a thicker oil it does leave a film up top for cold start as opposed to the fuel economy oils that leave the cam etc almost dry after periods of inactivity. This has been witnessed in the workshop of Bruce Buchanan, the Aussie mechanic in the 2nd link.

To be fair Pat i'm advocating using appropriate oil to suit the way you drive your car and where you drive it. Clearly if you use the car on track alot in hot temps as you do, then a more viscous oil needs to be used. I'm not sure what oil temps you're seeing on track, but the warm oil viscosity rating is the viscosity at 100 degs C. If you use the car on track in Sydney and use a 60 grade oil, it will get hotter than 100 degs C, so at maybe upto 120 degs C (?) it will probably be around the equivalent of 40 viscosity rating of my oil at 100 degs C in Derby, as I doubt my oil gets much above 100 degs C - even on track. So if you use a 40 grade oil on track in Sydney then clearly you are dicing with death.

I just don't understand why you would deviate from Porsches recommended specs, unless you were using the car more arduously, like heavy track duty for example, where the oil would get upto higher temperatures.

AntB · Jun 10, 2009

Right - just been to my garage and I have enough of the following oil to do the change on the 944

Comma Semi 5w30 = Taking this post into account - no good for this engine. Ive used for fords zetecs etc etc
Comma Semi 10w40 = Is ok with the 944 engine and often the recommended oil - although potentially not the best.
Shell Fully Synth 5w40 = Potentially OK - but possibly not the best for the 944 engine
Castrol Magnatec 15w40 = This would be Good????
Mobil 1 Motorsport 15w50 = This would be Good????

So going by what I have I think its one of the last two based on advice in this post - so which one shall I use... ????

I dont have a 20w as I have never used a 20w on anycar I have serviced / worked on - but a 15w should be more than adiquite I think dont you??

Thanks all in advance - Anthony

p.s. incase you forgot its a 2.7 8v engine

944 man · Jun 10, 2009

Id use the Castrol, as this is an experiment and itll be the cheaper oil.

AntB · Jun 10, 2009

ORIGINAL: 944 man

Id use the Castrol, as this is an experiment and itll be the cheaper oil.

OK..

without sounding daft!

what is the best oil (grade) that you would recommend to me... 78K on the clock etc...
Sorry - I know its been over many times above... and I seem to think you rated a 20w50? that was my thinking behind using the 15w50 as its nearly there?

Cheers mate - appreciate your expert help

944 man · Jun 10, 2009

Id recommend a 20W- with a 15W- as the next best thing. Ideally a synthetic as its obviously superior oil, but it really depends on your car: some thrive on synthetic whilst others leak it all over...

For an experiment to see whether a thicker oil will reduce oil consumption Id go for the cheaper oil, trying costly synthetics for suitability if the initial test was successful...