Hot Engine Oil Pressures

[edh]

You could try 10w50 or even 10w60
(The higher the second number the thicker it is when hot)

Mobil 1 or Millers CFS maybe

Might also be worth a go with Valvoline Racing mineral (20w50) or semi (10w60) first as it's much cheaper. I think that a 60 weight oil is probably overkill for a road car. 20w50 might be a bit thick in a scottish winter...

 

[scam75]

Ok thanks, never knew the significance of the 2nd number before. I will definately try a 10/50 or a 10/60. Incidentally, what does the 1st number mean?

Cheers (Oil novice!)

Stuart

 

[944 man]

For any performance car, its the second number which is more important. Newer tighter tolerance engines may be able to cope with 0W-30 oils, but old turbos need as high a second number as possible.

The first number (W=Winter) refers to the oils viscosity at low temperature. Theoretically the lower the better, because this means that the oil is more freely flowing and less draggy.

The second number refers to the oils viscosity at high temperature. Theoretically the higher the better, because this means that the oil is retaining its viscosity and is less watery.

In practice the first number is a compromise between whats ideal and what your engine will work with, and the second number is dictated to a greater degree by this choice (because no one can make a 0W-60 oil).

With a higher hot rating an oil should retain a greater viscosity under pressure, remaining effective and giving a higher oil pressure when hot, than oils with a lower rating.

 

[edh]

I sense this thread could run & run now...

I'm off to the nurburgring []

 

[scam75]

Thanks again lads!

I shall be going for a 10/50 or a 10/60 fully synth then once this baby is fully run in!

Stuart

 

[944 man]

Further to the above, remember that oils viscosity naturally changes with temperature: at -20°C oil is trying to be like treacle, but we need it to be just like it is in the container and at 120°C oil is trying to be like water, but we need it to be just like it is in the container.

Oil companies are trying to create oils whose viscosity remains constant across a broad range of temperatures.

 

[944 man]

944 dry sump kit:

http://www.ebay.co.uk/itm/150537795878?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Kept as an eBay watched item for several years, for no good reason. [] No mnetion of scavenge pumps or sump changes which youd expect, but I kept it anyway.

 

[Copperman05]

Simon at OPIE oils does not recommend a 10w60 in our engines as its just too thick, I have to agree. I very thick oil like 25w50 or 10w60 (10w60 is considerably thicker than a 10w40 when cold despite the 10w rating) creates more friction and therefore more heat, less oil flow and very long warm up times in winter. Unless you specifically need it (BMW M series) I would stay away.

A good fully synth 10w50 will be more than enough for any 944 application and the Ester variety will remain thicker than even most semi 10w60's at higher temps. If your engine is a recent rebuild and you using a 15w40 that should be fine, whilst a thicker oil may mask the issue if you have a noisy lifter I very much doubt it is down to the oil, (as 15w40 isnt exactly considered a thin oil). I would speak to your engine builder and see what they have to say on the matter


Edd

 

[scam75]

Cheers Ed

We knew about the noisy lifter, changed one while in but obviously something not quite right with another. If a slightly thicker oil stopped me hearing it that would slow down the need to be replacing more lifters! It's not that big a deal, just curious about other oils.

It may also just be a bit of crud blocking a lifter and it may well clear anyway through time.

Cheers

Stuart

 

[944 man]

I dont dislike Opie oils, quite the opposite, in fact. Simons advice is poor though, as quoted by Edd, although its better than it used to be, as he used to recommend - 0W! This is because he knows nothing at all about the cars and he was following oil manufacturers guides (Mobil still recommend 0W M1 for the 924S, whichd be funny, if it wasnt so bad) - he has now modified this based on what he has picked up, but its still only generic, at best.

Edd, you always think that I disagree with you about oil, but I dont. Synthetic is always better, but the grade is very important. Some cars run well on very runny synthetic oils - your S2 and my old series one car do, but many dont. Not because theyre synthetic, but because they arent thick enough to stay in the cars (lost though the exhaust, not on the garage floor).

Opie's advice is at odds with that given by specialists with experience of the engines, JMG being a good example. For people who dont understand the ratings, a retailers advice can help, but I dont think that it should be blindly followed, particularly where its at odds with far more experienced advice and empirical evidence.

I suspect that you know a great deal more about which oils suits 944s than they do, although your opinion is swayed somewhat by the cars original manual (when Porsche recommended 'fuel economy oils' as they were known then - remember too that Porsche now recommends 0W oil for 944s, which shows that their recommendations arent always to be followed) and by the fact that your S2 engine has remained particularly and uncommonly tight.

 

[Copperman05]

I do enjoy our little discussions and that is your opinion Simon, I hear what you say, but my opinion is mainly swayed by many hours of research and goes beyond that of the opinions of Simon at opie. My interest in oil goes beyond most, its a subject I find somewhat fascinating (as I don't have a life!). I could equally say that I would not always believe the opinions of a mechanic or garage on oil as they are just not well enough informed as you might hope.
Whilst I might think my butcher makes great sausages it doesnt make him a good cook! and I think the same applies to mechanics, engine builders and oils. They will often recommend what they have, based on what they can get and how much they pay for it.

Personally I dont think there is anything wrong with using a 0w40 oil in our cars if we could have done so from new, now most have done well in excess of 100,000 miles+, engine wear and oil consumption dictates otherwise. Will using 10w60 oil blow your engine up? No, but I stand by my previous post, an ester 10w50 is more than enough for even the hottest of track days and ensures good oil flow, whilst allowing you to run the car in winter keeping cold weather wear to a minimum.

Your needs may be different of course.


Edd

 

[Hilux]

Sits back with popcorn....................[]

 

[944 man]

I dont disagree with what Edd has written. Its agreement dressed up as disagreement for the most part. The 'who do you trust' argument applies equally to shopkeepers who sell oil as it does to garage owners who repair cars, hence my being careful about who I listen to Jon Mitchell, Barry Hart etc).

Remember too that a top quality ester (Gp.V) -50 will be a good deal thicker at 110C than a reasonable-good PAO (Gp.IV) or semi-synthetic (Gp.III) -60! []

 

[Copperman05]

ORIGINAL: 944 man


Remember too that a top quality ester (Gp.V) -50 will be a good deal thicker at 110C than a reasonable-good PAO (Gp.IV) or semi-synthetic (Gp.III) -60! []

With some oils you could even say this about the group v -40 grade oils being thicker than the group iii -60 grade mineral/semi at higher temps. Which goes to show how important HTHS numbers are when comparing oils, over the thicker is always best analogy.


Edd

 

[Diver944]

Barry Hart did a back to back test with three different oil grades on Paul Folletts track 968 after a rebuild some years ago. I'll try to find a link to the actual data but it was something like 0w40, 10w40 and 10w60. With the 10w60 they saw a power loss of something like 10 bhp compared to the 0w40. Obviously a track 968 needed all the horses it can get compared to our Turbos at the time so Paul switched to the 0w40 []

 

[Copperman05]

And that 10bhp has not just disappeared its very likely to have been converted to heat via friction, not something you want your oil to do, and not good for a track car either!


Edd

 

[944 man]

With a lovely new engine, Id be using a Gp.V 0W-40 in a flash.

 

[zcacogp]

ORIGINAL: Hilux

Sits back with popcorn....................[]

Care to share it? []

>MakesMyselfComfortable<


Oli.

 

[Hilux]

.....................pauses from eating....................

Oils have come a long way since the mid 1980`s so most half decent oils are probably as good or better than Porche`s original.

A thicker oil will work better if 1) the pump tolerance/wear is designed for it and 2) clearances are worn or uneven for engines today are almost blueprinted in tolerance.

Equally it is flow you need and the right amount as it takes heat from components so a viscosity drop puts pressure on the pump to keep up. Its cooling or removing the heat from the oil thats key not the oil itself. Keep a decent oil around 90-100 it`ll last for ever.

I would have thought any 10-40 would work but a fully synthetic 'might' offer assurances over other oils. I would suggest my 2.0L 16v Golf gets caned far more than most S2's or Turbo`s (apart from the Turbo bearings) and I use a good quality Fuch`s semi that isnt expensive - I just change it now and again and it runs around 100 temperature on track.(115 max when weather is warm) and uses a simple water/oil exchanger. If the temps go up I`ll add a cooler.

For road use stop worrying I say [8|]

..........................munch munch...............

 

[TTM]

The specialists I know of who have rebuilt and raced more 944 engines that I could think of all run fully synthetic oil, no thinner than 15W50 or 10W60.
The workshop friends & I have used to prepare/rebore our 944 blocks recommend 15W50. Field experience and user feedback has more value to me than what a global oil reseller may say, but I'm well pleased to still buy from Opie as he regularly offers interesting discounts []