Engine Oil

[robwright]

Guy,

Could you email me a price list for your oils to see how they stack up to my local factor please mate. I think I might go for the Silkolene. It seems to come highly reccomended. When I make the change I take it that is adviseable to do the filter also? I noramlly would be looking at filter every 12 and oil dropped every 6. Current filter has been in around 3 months.

Cheers,

Rob

 

[edh]

Rob - I'd try the Silkolene 15w50 synth from Opie - it's about the best I've used

Bear in mind a compression test will only tell you about the state of the top ring - the other rings may still be the cause of the problem (neads a leakdown test to diagnose?)

You could try fitting a catch tank (not much space to put it with the airbox in place) and see what gets pullled through.

I'm sure I read that PSH used (and rated) the Ametech treatment - it still sounds like snake oil to me but might be worth getting his opinion on how it worked with his car.

 

[robwright]

You are quite correct Ed but I also know from my work on locomotive engines that bad compression rings can allow excessive wind into the crankcase and lead to excessive pressure and ultimately more vapour escaping from it. In a loco engine's case this is safely vented into the exhaust/turbo stack via a seperator screen. Where does the crankcase vent to on our cars? Is it back into the air intake system? I think Scott mentioned there is an air/oil seperator isn't there?

 

[TTM]

Using anything thinner than 10W40 in a well-used 944 engine is playing with russian roulette, especially in a 944 turbo engine.

I switched from Castrol RS 10W60 to Motul 300V 15W50 following advice from the workshop where I had my (Alusil) block prepared. They put it in about any engine that goes through their hands, ranging from Porsche 935 to Velocette KTT.

 

[edh]

The AOS breather connects to the rubber J-boot in front of the turbo intake. The metal pipework is connected to the Cycling valve pipes (you can see them disconnected in this pic as the CV is now bypassed)

If your turbo intake is very oily then that's a sign your blowing a lot of oil out of the crankcase.

here's mine with a catch can fitted (connects to the J-pipe after the MAF) I've removed it now. You can get them on ebay for about £30-40 I think

 

[333pg333]

Curious how significant the supposed charged particles in Magnatec cling to our Alusil cylinders?
I'm in agreement with Thom. I wouldn't put a 10w/40 anywhere near my engine let alone a 5w/40.
Remember that the Porsche manual recommends a mineral based Multigrade oil of 20w/50 down to below freezing temps (-10oC)...and this was on cars as recent as some 996 models.

For those of you that really care about what you put in your engine, here is a most excellent and detailed thread that is relevant to our 'flat tappet' motors. One of the main contributors on this topic, Charles Navarro is a leading expert in this field. I have saved this thread and return to it semi regularly.

http://forums.pelicanparts.com/porsche-911-technical-forum/367300-ultimate-motor-oil-thread-why-we-hate-cj4-sm-oils.html

http://tinyurl.com/yzrxn2t

 

[Copperman05]

Here we go again, a common misconception regarding oil vicosity it seems, I would say 10W60 is probably much more damaging to these engines as it wont be thin enough to lubricate it properly at working temperature.

The porsche manual 1989 Turbo and 944 also recommends 'all season' fully synth or hydro cracked oils such as a 5W-40 and actually calls it a high performance oil. We have all been here before, one should not automatically put extra thick oils in these engines, you may be doing more harm than good.

Edd

 

[333pg333]

When you say high performance oil you of course mean "Fuel economy oil"...and yes, here we go again.
As far as lubrication goes, I'd rather my oil be on my camshafts, tappets etc when I start it up as opposed to low visc oils that drain down into the sump overnight. Also as far as protection to the bottom end of my motor goes, I'd also rather an oil that is going to stand up to the rigors of not only spirited hwy driving but also the track. Low visc oils like a synthetic 5w/40 become like hot water under those circumstances and do not provide a protective barrier that a higher visc mineral based multigrade oil does.
A 5w/40 would probably be sufficient if you just wanted to potter about the local village of course.

 

[Copperman05]

Yes thats the table I was talking about, thanks. At the bottom Porsche recommends, yes thats right 'Recommends', using 5W-40 oil for all season use, it lists it as a fuel economy oil as it is a synthetic oil which provides less drag and therefore improves fuel economy slightly. This oil is superior to mineral oil, and is a 'high performance oil' porsches words not mine.

5W-40 is the same viscosity as 10w-40 15W-40 20W-40 at working temperature, so it is not like water as you suggest but exactly the same viscosity at working temp as the other oils, the only difference is the cold weather temperature viscosity.

Your assumption that thick oil is better becasue it doesnt drain down into the sump is incorrect and this it not how oils are designed to be used. Thin oils are BETTER at start up because they are thin, thick oils are less effective at low temps, this is common fact. A thin oil is able to be pumped around the engine much quicker at low temps lubricating the engine, a thick oil takes much longer to circulate and therefore more wear occurs. Notice on the graph you have posted that as temperatures get lower the recommended oil viscosities also get lower, I'm not just making this up...

Edd

 

[edh]

I think we have 2 different (maybe 3) audiences here - ones who are most concerned with track performance (Patrick), where oils get very hot (and thin), others who want a good oil for road use (Edd), where the car is likely to do more short journeys, and maybe a third (Rob) where the engine may be using / losing a significant amount of oil. This means that there is more than 1 "right" answer.

My biggest concern with 0w or 5w oils on a road car would be their propensity to leak/seep when the engine is cold.

In normal road use these engines are very strong and reliable. Regular changes of any decent mineral or synth oil should work fine IMHO. There are many more pressing issues to worry about on a 20 year old car than oil grade.

 

[Copperman05]

ORIGINAL: edh
There are many more pressing issues to worry about on a 20 year old car than oil grade.

Maybe, but talking oil grade is fun. Isnt it?[&:] Ed you are right of course, different uses calls for different oils. I'm sure we will be discussing the finer points of oil for many years to come and the different opinions will undoubtedly remain.

Edd

 

[edh]

All part of "the game" I think Edd []

BTW - I tried out some valvoline racing 10w60 semi synth recently - not as good on track as my favourite synth oils as pressure dropped off significantly once the temps went over 110 degrees.

 

[oilman]

ORIGINAL: robwright

Guy,

Could you email me a price list for your oils to see how they stack up to my local factor please mate. I think I might go for the Silkolene. It seems to come highly reccomended. When I make the change I take it that is adviseable to do the filter also? I noramlly would be looking at filter every 12 and oil dropped every 6. Current filter has been in around 3 months.

Cheers,

Rob

Rob,

All prices are on my site here http://www.opieoils.co.uk and you get 10% club discount, plus any offers we have on top, and there are offers on all the time.

The Pro S would make a very good top choice.

Cheers

Guy

 

[oilman]

ORIGINAL: 333pg333

Curious how significant the supposed charged particles in Magnatec cling to our Alusil cylinders?
I'm in agreement with Thom. I wouldn't put a 10w/40 anywhere near my engine let alone a 5w/40.
Remember that the Porsche manual recommends a mineral based Multigrade oil of 20w/50 down to below freezing temps (-10oC)...and this was on cars as recent as some 996 models.

For those of you that really care about what you put in your engine, here is a most excellent and detailed thread that is relevant to our 'flat tappet' motors. One of the main contributors on this topic, Charles Navarro is a leading expert in this field. I have saved this thread and return to it semi regularly.

http://forums.pelicanparts.com/porsche-911-technical-forum/367300-ultimate-motor-oil-thread-why-we-hate-cj4-sm-oils.html

http://tinyurl.com/yzrxn2t

The only reason I would put a 20w-50 in one is if the engine is very worn or in a very hot climate... Like where you are.

In the uk SAE40 or SAE50 with 5w 10w is ideal or for the hardened track goers 15w.

Cheers

Guy

 

[TTM]

Since wear is the only relevant data we should agree on, we would need to know, for a given type of oil, how much wear occurs during a "cold" start up and how much wear occurs when the engine is already "warmed-up" and is actually being run in given running conditions.

However I'm not sure 944s are at their best when used as shopping trolleys []

 

[oilman]

There are lots of factors and variables to this, state of the engine? State of tune of the engine? Type of oil used? How long the oil has been in there? The temp the oil has been running at?

You will just go round and round in circles trying to pin down one answer.

Cheers

Guy

 

[edh]

ORIGINAL: TTM

However I'm not sure 944s are at their best when used as shopping trolleys []

I see you have the "shopping" model as well as the "performance" variant []

 

[Diver944]

ORIGINAL: oilman

You will just go round and round in circles trying to pin down one answer.

Yup it's what we do

Often

 

[robwright]

Well guys I hope this thread hasn't lost the plot. It was certainly not my intention for it to do so [] I will apologise for posting about oil her in the first instance as I did not know oilman's technical article existed. If I can say it has been entertaining to say the least. Believe it or not it is also comforting to know that so many of you care so passionately about your cars and indeed what you put in it!! Would we be having the same conversation about a Ford Mundano? I think not. In response to my original post I think I will just have to live with the oil usage for now and accept it as a consequence of increased boost and a child like need for speed [] I will however be swapping to a fully synth oil probably Silkolene Pro S - a 10W40 me thinks. God I hope this doesn't set everyone off again lol [] Thanks again for your responses. Rest assured I have read everyone of them. It's good to know you guys care. Oilman thanks for the price list - shall have a good look later.

 

[sawood12]

ORIGINAL: 333pg333

Curious how significant the supposed charged particles in Magnatec cling to our Alusil cylinders?

The oil doesn't cling to the alusil cylinders but it does cling to the wearing surfaces of the cams, bearings in the engine and all the ferrous metal surfaces the oil comes into contact with. Ester oils are no gimmick. They are the only thing that can be used with modern gas turbine engines as when those things start up they spin up very quickly for a good 30 seconds or so before they start up and oil starts to circulate properly through the engine so they need adequate protection during that phase hence the use of Ester oils. Unlubricated bearings will last a few seconds in a gas turbine enigne unless properly lubricated so that is how effective Ester oils are.

The oils Porsche recommended for our cars 20yrs ago took into account the state of the art in oil technology of the day. That was 20yrs ago and things have moved on significantly. If Silkolene Pro was around 20yrs ago i'm sure Porsche would have spec'd it.

Also i've said it before and i'll say it again - thicker oils (i.e. oils that are too thick) offer less protection - not more. A thick oil doesn't flow as well as a thin oil. Oil pressure is not a measure of adequate oil flow over the moving surfaces. You restrict flow you reduce the lubrication effect of oil and reduce the cooling effect the oil has. Use the oil viscosities Porsche recommended irrespective of milage or age. 5w40 - 15w50 has been proven to be a perfectly safe and fine viscosity range for oils in the UK climate for normal street use.

Also don't scrimp on oil. £40 for a decent can of top quality oil is cheap on a cost per mile basis. We put a higher value of petrol in our cars every 300 - 350 miles.