Engine Oil - 2.7 - what do you use

[AntB]

OK great - thing is mine uses no oil between changes anyway, so happy with that... and the oil is golden clean.. Its just 6k ish since last service and I want to do a change every 6K as that is what the car has had for the past 6 years..

A

 

[944 man]

Sorry. If you arent using oil then Id suggest going with the best quality oil. I confused this thread with another about excessive consumption.

 

[Copperman05]

Why use 15W or 20W when there are much safer oils to use for winter temps. The 944 manual says you can use down to 5W synthetics, I would suggest a 5W40 good quality synthetic, or maybe 10W50 if you do track days, drive particuarly hard.

Edd

 

[944 man]

The 944 2.7 manual doesnt say that. It clearly states that 5W- oils should be used where temperatures reach -30c and never above freezing and for fuel efficient oils it clearly states that a minimum 10W- grade should be used.

15W-40 is perfectly safe for an English winter and 20W- also on all but the odd sub-10c morning. Youre posting nonsense and it doesnt help people. Eighties engines do not need, nor do they benefit from 5W- oils and this opinion will be echoed by any knowledgeable independant specialist. The notion that 5W- and 0W- oils suit these cars, 'because theyre Porsches' is foolish in the extreme.

 

[Copperman05]

944 man. Firstly you state that these viscosity's are not recommended by porsche, I provide evidence that they do, now you choose to call my postings nonsense.

I have already posted a scan of the manual on this thread if you care to read it the recommendation to use 5W-40 synthetic oil is there for you to see. I do not agree with your assumption that low viscosity oils are not suitable for these engines. There are other issues around increased oil consumption and one shouldnt automatically point the finger at low viscosity oil (different oils effect engines in different ways, Mobil1 0W-40 may cause increased consumtion in an engine where Amsoil 0W-40 does not, this having nothing to do with viscosity). If you have suffered a drop in oil pressure wouldnt it be prudent to ensure you do not have a faulty pressure gauge before claiming all low viscosity oils are unsuitable for 944's. Also all engines are different, they have different servicing historys, different oils used over the life of the engine, high mileages, low mileages all these things effect how an oil behaves in an engine. What doesnt work in your 944 does not mean it doesnt work in all 944's.

Would you like to provide some evidence to illustrate your theory's on low viscosity oils?

In the meantime we will agree to disagree, but we all have an opinion on oil and yours is not the last word I'm afraid.

Edd

 

[944 man]

Ant, youll have to decide whose advice to follow.

 

[AntB]

just a thought here... a slight drop in oil preasure may not be a bad thing surley... If you are using a top quality oil and you have lost a little oil preasure - surley this means that its just 'easier' for he oil to flow around the engine?

 

[333pg333]

Also bear in mind that the manual in eg '94 didn't recommend Fuel Economy oils of 5w/30 or 5w/40, it shifted up to 10w. In the Multigrade section (that is shaded which suggests that is what is the most suitable part of the list) there is a 5w/20 for -30 to -10c range, a 5w/30 for -30c to 0c. There is no 5w/40 even listed.
Further, it can be speculated based on experience that the 50 in a larger spectrum oils such as a 10w/50 vs the 50 in a 20w/50 are not the same 50. The ones in the wider spectrum oils have large doses of Vii's which are designed to artificially affect the molecules in these synthetic oils to act like a higher visc in a mineral oil which has high levels of ZDDPs. So what is on the bottle is not always what they actually are.

 

[333pg333]

ORIGINAL: Copperman05

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.

By definition a 'Fuel economy oil' requires you to drive at low rpm and under a little load as possible. Otherwise how are you going to achieve a good Fuel economy. If you want to drive like this then you can get away with one of these oils. I would say that even the most conservative owners of these cars will occasionally get the engine to heat and give the car a bit of Welly. These oils are not suitable for our cars to get into the boost. You will not have sufficient protection for your motor by using these oils. Your choice of course. []

Another urban myth is that some of these oils are totally synthetic ie made in a testube without any base crude oil in the mix. Simply untrue. All oils available for general sale to the public start with a base crude oil.

 

[AntB]

OK - this is all great discussion and info.. I have some more thought...

If you look at the thickness of an SAE 40 oil as an example at 100degrees, its actually thinner then than when its cold - cold rate 5w... Same for SAE 50 etc... So what I am trying to understand is, with that theory, the 5w should not hurt at all as its actually thicker when cold than it is when at running temp?

 

[Copperman05]

ORIGINAL: 333pg333

In the Multigrade section (that is shaded which suggests that is what is the most suitable part of the list.)

I dont agree, it is shaded to differentiate between the three different sections, nothing more, if there was a 'More suitable part' why dont Porsche just say so?

All these oils are recommended by porsche, I dont think porsche was saying use these multigrade oils (they are good) and use these fuell economy oils (but they are not so good), as that would not be a recommendation would it...

 

[Copperman05]

ORIGINAL: 333pg333

By definition a 'Fuel economy oil' requires you to drive at low rpm and under a little load as possible. Otherwise how are you going to achieve a good Fuel economy.

Once again this is incorrect, they are called fuel economy oils because lower viscosity synthetic oils are more fuel economical (by their physical make up), it does not require you to drive more economically. I do think that Porsche has caused some confusion by calling these oils fuel economy oils and in my eyes should have just called them synthetic oils (as thats what they are), but I guess it was trying to talk in laymans terms so people could understand the differences between the oils and the advantages of using synthetic oil.
Can you provide evidence to your claim that these oils are unsuitable and dont provide enough protection, or is this just your guess?

I agree that low viscosity oils in older cars (I mean older 50's-60's, not late 80's) can exaserbate existing problems, but if you have a good, regularly serviced and well maintained engine that hasnt done excessive mileage (say over 150,000) I dont see why you shouldnt use a good quality synthetic and benefit from the advantages that it gives you.

Yes of course synthetic oils use the same base oils, otherwise you would never be able to mix to two, and there are differnt ways of making synthetic oils, (hydrocracked, ester oil, etc) and these also change the properties of the oils.

Edd

 

[edh]

The thread that Patrick linked to on page 1 is well worth a read - OK, it's for aircooled Porsche engines, but very interesting nonetheless. Some good "evidence" there i think

 

[Copperman05]

ORIGINAL: edh

The thread that Patrick linked to on page 1 is well worth a read - OK, it's for aircooled Porsche engines, but very interesting nonetheless. Some good "evidence" there i think

This thread appears to be concerning the reduction in ZDDP wear reduction additives in oil and also recommends oils such as those made by Redline and Royal Purple as having a high ZDDP content.

Both Redline and Royal Purple are well known manufacturers of low viscosity synthetic oils, including 0W-40, 5W-40, etc.

 

[tr7v8]

ORIGINAL: sawood12

ORIGINAL: Neil Haughey

ISTR the problem with top end wear is allegedly due to the thin oils running out of the head when the car is sat, hence when started up, the engine for a few seconds has very little or no oil on the camshafts etc. I have no idea how true this is but there does seem to be anecdotal evidence that cars run with thicker oils have shown much less top end wear. ISTR an Australian 928 specialist had some stuff about this on his website.

The problem with thick oils is that the oil actually provides less protection. If you ever drag your finger along the bottom of a bowl of porridge (once you've eaten it of course) you will leave a dry line. That is what is happening with an oil that is too thick. If you use a thinner oil the oil (or porridge in this analogy) is dragged back behind your finger and leaves the surface wet - hence better protection. So as long as you have a good flow of oil being provided to the moving surfaces then you are maximising your protection. Also you are not getting as good a flow of oil if it is thicker - you will get less flow of a thicker oil at 5 bar pressure than a thinner oil (back to the sucking milkshake through a straw analogy).

Clearly an oil does need a certain level of thickness or we'd all be filling our sumps with 3 in 1. The reason I think oil has to have a level of thickness is to resist against the oil from being squeezed out from between the two moving surfaces. Again the developments in modern fully synthetic oils massively improves this characteristic in thinner grades of oils. So you are trying to balance out wanting a nice thin oil to improve oil circulation around the engine and maximise wear protection, and having an oil with some level of thickness to actually allow the oil to do what it is supposed to do.

In terms of fully synthetic oils - I see no good reason NOT to use a fully synthetic in any car (other than proper classics). There is not one benefit that a semi synth (which are just a marketting con as they contain such a minute % of synthetic content) or mineral oil has over a modern fully synth oil. Modern fully synth oils withstand temperatures better (important in turbocharged cars), are more resistant to breakdown due to contamination of water, fuel and products of combustion, are more stable (i.e. maintain their properties longer - oils become acidic over time which eats away at your engines internals, fully synths get acidic much more slowly). The reason why modern cars can go 20k miles between services is due to fully synth oils.

Sorry this is wrong on a variety of levels.
Bearings are protected using hydrodynamics, so using your porridge analogy then if you drag your finger at many MPH then it'll ski like a water skier, that is what happens with a plain bearing (rod or main). Oil pressure in the bearing is around 20,000psi!
Once hydraulic tappets drain down they can take a while to fill & pump up, better that they don't empty in the first place.

Synthetic oil has little relevance to non-turbo cars of the 944 period. Mine is currently being changed at 2K or so, which is the mileage I'm doing in a year, One purpose of synthetic is to extend service intervals so you'll be binning a 1/4 used oil which has what point? Also the reason oil comes out black is suspended carbon from blowby on high mileage engines, I'd far rather get that out as often as possible rather than leave it in for 12,000 miles or so.

 

[Hilux]

Wot he said

 

[333pg333]

Yet more evidence. As for real situations where the lower visc (synth) is unsuitable, read the response from JET951 aka Bruce Buchanan.
http://forums.pelicanparts.com/showthread.php?t=477001

 

[333pg333]

ORIGINAL: Copperman05

ORIGINAL: 333pg333

By definition a 'Fuel economy oil' requires you to drive at low rpm and under a little load as possible. Otherwise how are you going to achieve a good Fuel economy.

Once again this is incorrect, they are called fuel economy oils because lower viscosity synthetic oils are more fuel economical (by their physical make up), it does not require you to drive more economically. I do think that Porsche has caused some confusion by calling these oils fuel economy oils and in my eyes should have just called them synthetic oils (as thats what they are), but I guess it was trying to talk in laymans terms so people could understand the differences between the oils and the advantages of using synthetic oil.
Can you provide evidence to your claim that these oils are unsuitable and dont provide enough protection, or is this just your guess?

I agree that low viscosity oils in older cars (I mean older 50's-60's, not late 80's) can exaserbate existing problems, but if you have a good, regularly serviced and well maintained engine that hasnt done excessive mileage (say over 150,000) I dont see why you shouldnt use a good quality synthetic and benefit from the advantages that it gives you.

Yes of course synthetic oils use the same base oils, otherwise you would never be able to mix to two, and there are differnt ways of making synthetic oils, (hydrocracked, ester oil, etc) and these also change the properties of the oils.

Edd

Yet again you're incorrect. They were labeled fuel economy oils as that is exactly what they were designed for at the time. I am not basing my opinions on , well just that, an opinion. My basis is from mechanics and techs that have come to the same conclusions. All the excessive wear comes down to using too light an oil and usually it is also synthetic. I'm not making this up just to be argumentative. You clearly want to use a 5w/40 or equivalent. This is your absolute right and don't let me deter you. All I can say is that you are increasing the chances of engine wear and even failure by doing so.

 

[Copperman05]

The fuel economy oils are not inferior, they are in fact superior to the multigrades listed above them. That is why Porsche calls them 'high performance oils' (you can read this in the scan I posted) it just so happens that they provide better fuel economy too.

 

[Hilux]

it just so happens that they provide better fuel economy too.

How, and if they do - how much of a saving in fuel use?

Dont believe it!