DarylJ

Oil is almost a religious level topic here. I've gone with the conventional logic of using a 20w50 because it keeps my oil pressure up where I though it needed to be. Over the winter, I probably should have put 10w40 in, as some mornings were ugly sounding for the first 10 seconds after start up.

I didn't have much of an opinion on the synthetic/synthetic should not be used in our cars because the motor wasn't designed for it, or the occasional nutjob who looks for "classic" old stock oil so they can put what the factor actually recommended in their car.

That being said, I just dropped down to dino 10w40 tonight. I'm going to see what kind of difference it makes. Why? Because of this:

http://www.ferrarichat.com/forum/faq...=haas_articles

Ferrari guys are usually really boring, and would rather talk about the lubricant used on the machine at the factory that cut their paddle shifters than to get out and drive (unless they are driving to a place where they can talk to other boring people about that kind of thing). This guy is no exception. But he did do a LOT of research, and some of it sounds credible. It's worth a read, and I'd like to know what other people think about all of his spewings. It has made me think differently about what a motor really needs out of oil (mostly, pressure is NOT the most important thing).

Most of you should put this thread on ignore right now. I'm just warning you.

Mark944na86

Actually, these engines _were_ designed for synthetics, even though they weren't yet widely available. Porsche knew what was coming, and planned accordingly.

Synthetics are pointless in worn engines. If your engine is burning oil, don't bother with synthetic -- you'll just burn it faster. Match the grade of oil to the current state and needs of _your_ engine -- there's no one size fits all for 20+ yo cars.

I use 5w-50 Mobil 1 full synthetic year round with a mild climate, because a) that's what Porsche says to use, b) that's all it's ever used since new, and c) my car burns less than 1 litre of oil between changes (every 10K kms, ~6000mi).

smlporsche

Wow That took a while but confirmed what I "knew" all along...

"More confusion occurs because people think in terms of the oil thinning when it gets hot. They think this thinning with heat is the problem with motor oil. It would be more correct to think that oil thickens when it cools to room temperature and THIS is the problem. In fact this is the problem. It is said that 90 percent of engine wear occurs at startup. If we are interested in engine longevity then we should concentrate our attention at reducing engine wear at startup."

and is also the reason Porsche now reccomends 0W-40 synthetic in all their water cooled engines. Daryl, you should really consider switching on your next change. That sound you heard when you started it up is NOT good

Let the stones start flying...

bearone

#1, you shoudln't be running 20-50 in a cold climate and as i recall, pa is cold in the winter time.

the owners manual specifies/recommends what wt, for what temp ranges.

87951
95sl320 dd

DarylJ

You've missed the point of the thread by not reading the mini-dissertation at the link I posted.

DarylJ

Noisy tappets at startup/idle is not nearly as bad as the stuff that's not making any noise. And THAT'S the important part that I was taking away from this - and not just when you're below temperature.

The importance of keeping your oil pressure BELOW your OPRV blow-off when you are below redline was the most important thing I read there. That's a terrible paraphrase of what was said, but its a concept I hadn't thought about.

The TL;DR version of that is basically, if you max your oil pressure out low in the RPM range because of the thickness of your oil, dropping down to a thinner oil (second number, we're not talking about the first) will drop your pressure and allow for more flow, as you aren't hitting your OPRV cut-off as soon.

This is a really important thing to understand. To make matters more complicated, the oil weight does not directly correlate to it's at-temperature viscosity. You have to dig into spec sheets for that kind of information.

M758

I run 20w50 year round. However my temps range from a worst of maybe 30F to a peak of 120F.

That calls for thicker oil.

944Ross

It really doesn't; it may call for a cooling system upgrade, or a different oil cooler. That is one of his points.

I doubt anyone will take the time to read through that whole write-up; I didn't. What I saw looked good, but could have been said in a quarter of the words.

rattlesnakeracing

DarylJ - my 2 cents worth - Everything that Dr. Haas wrote relating to lubrication makes good chemical sense if it pertains to metal holding oil and moving mechanical parts.

The difference between oil operating temperature pertaining to the W value test should be made clearer to the public, instead of mass marketing to produce the sell of petroleum products by oil companies and poor explanations about the oil. It's much easier to throw a picture/brochure of a couple of babes and a dressed up logo at people during an event than to hand out clearly defined specifications not corporate related to people, although I wouldn't object to a brochure with babes on the front and clear data on the back!

I also think that marketing may be part of the reason DarylJ is so repetitive in his remarks, if one considers publishing like he mentioned a source of revenue. Who knows? I do remember in Psych class that the professor stated for a person's brain to retain anything and store the knowledge it had to be presented 3 times. I've tried that with beer and mags but still have to keep indulging myself because I can't retain anything but a headache and sticky fingers (from oil?) the next morning.

It was good to find out the difference between "Racing" oil and "Normal" oil. I do wonder why not having additives in racing oil makes a difference, unless it pertains to viscosity or temperature retention. I probably need to read the thread again - I guess that is part of the 3 time thing for retention.

I do believe if we wanted no engine wear oil needs to be to heated to a constant point that never changes, like Dr. Haas stated, but then I think about how high the heat factor maintained over time would damage the oil. I guess the overall goal for cars relates to aircraft engines; an oil heater and a dry sump oil pan.

joonas

The best way to figure out what viscosity of oil you need is to drive the car in the conditions you will use. Then use the oil viscosity that gives you 10 PSI per 1,000 RPM under those circumstances. For some reason very few people are able to get this simple principal correct. I cannot explain further.

If 10 PSI per 1,000 RPM is the TRUTH then my 944S needs 68,4 PSI (4,8 bar) at rev limiter (6840 rpm).
Right now I use 10W40 semi - synthetic and with warm engine my oil pressure does not go to 5 bar at 5000 rpm. I just rebuilt the engine so I do not want to rev it to the limiter, yet.
Maybe I have OPRV problems but time will tell.

I spun #2 rod bearing twice allready. All I know is that during hard driving oil pressure was around 4 bar near rev limiter when I used 10W60 engine oil.
At col startup oil pressure hit 5 bar and more.

So if I needed 4,8 bar oil pressure and got only 4 the rod came knockin.

I plan to install the oil cooler and will use 20W60 engine oil to achieve the 4,8 bar oil pressure at rev limiter. If I still cannot get that pressure I have to start tuning the OPRV

bearone

no, i didn't miss anything, i live in the real world and go by what the mfg recommends.

i don't give a hoot what ferrari folks do/recommend.
i saw the scroll bar for the multi page doc and didn't bother.

87951
95sl320 dd

DarylJ

Yes, I'm sure you do.

You also have nothing to add to this thread. If you don't like the concept of questioning if something has changed in the last 20 years (like the oil that's available, or the mileage on the motor), you won't have anything to contribute.

I'm sure you'll do just fine using what the factory manual says. It's certainly not going to hurt anything. Some people are just more interested in specifics and fine tuning than you are, and you are under no obligation whatsoever to post in threads that are so beneath your level of experience and firm roots in the real world.

bearone

hey pal every time you start any vehicle it's the poorest lubrication for a few seconds.

i used castrol dino 20-50 in phx for 16 years and the 951 has seen valvoline synthetic/20-50 most of it's life.

my level of experience includes 33 years as a licensed faa aircraft mechanic plus working in/around cars for 40+ years.

i've sent in soap samples on acft and cars for years, STUFF WEARS OUT no matter what precautions you think you're taking/making.

running 20-50 in pa is one of the worst things you've ever done and swapping to 10-30 will increase op but won't fix any damage.

87951
95sl320 dd

theykallmekem

man, i never knew engine oil can get THIS technical .... i had a hard time choosing from Mobil 1 or Castrol lol.

Mark944na86

OK. My S2 engine has just over 174000 km (~105K mi) on it. Following just the mfg specs (Mobil 1 5w50, and changes every 10000km since new), it still burns < 1 litre oil between oil changes, and currently holds 3 bar pressure on warm idle, 5 bar on acceleration.

So what exactly is all this interesting "fine tuning" supposed to buy you over what you get from simply the following the mfg specs?