MC 968CS

Hi Jet951. I have been reading lots of the views around lately. Seems there are a lot of keyboard racers around.....I tend to take very little on board from forums anymore as a result.

Wondering what engine oil you suggest for our 968 type engines on track, clearly not M1!

JET951

Hi MC , I take it you are talking about Australian ambient temp conditions & what you can buy in Australia ? , because it would be a bit pointless mentioning an oil that you can only buy , say in the States ( as an example ) , so I have to go off your'e avatar to asume this

If its just club track fun driving , meaning the supersprints we do in the PCNSW , then its only a half a dozen laps per session , meaning not a full blown endurance race for three hours + & mutiple drivers over that three hours , because that will demand a completly different approach in set up , massive oil coolers & naturally oil/oils

So lets take the first ( probable one )
PCNSW supersprints and the like of event/s }
First of all the 968/CS has a very small stand alone oil cooler , for the road its more than enough , but for the track its completely inadaquate , we found that out a few years ago with Nik Priestons 944S2 at Eastern Creek ( mid winter ) I was lucky enough to spot Nik's ( seperate VDO ) oil temp gauge we had fitted to his centre console( sensor in sump) & the oil temp as he pulled up after a session on the track ( six laps ) was 150 degrees cel , I couldnt believe it ( six laps ) in a 944S2 , admittidly he does give his 944S2 everything it has on the track , but boy oh boy thats not good
Before the next track day we had fitted the much larger oil cooler that we fit to all the 951's we mod for the track ( club track work)
Since then the oil temp in Nik's 944S2 has not gone over 115 deg cel

Now why did I mention all that I hear you ask ?

Very simple , the oil viscosity in a last century Porsche & its temp ( on the track ) are as important as each other

Subnote} on this planet , as engine oil becomes hotter & hotter ( say 150 deg cel +) the oils gets extremely thin ( for want of better expression) & its ability to do nasty things like foam which puts no 2 conrod bearing at instant risk & to loose its ability to keep metal components away from each other ( oil film strength ) becomes criticle & just as bad the oil is irrevocably damaged & its no longer the same

Whats interesting is that the massive use of last century ZDDP & Moly ( Moly enhaces the effectiveness of ZDDP) is used in all "Racing" ( non emmission compliant road oils ) be it so called synthetic or so called partial synthetic oils & conventional oils even though the whole premise of the so called synthetic engine oils was a breakthrough in technology , only to find out ( these days ) to make engine oils to do their job ( keep metal parts away from each other) so called syntheic engine oils rely heavily on last century Dino solutions of ZDDP ( WW11) technology ( what a joke)

I mentioned ZDDP because ZDDP is extremely important to a last century Porsche with high loaded flat tappet designed overhead camshaft engine & the 968 engine is a high loaded flat tappet design , these engines must have High Oil Film Strength oils , remember there is no oil pressure between the cam lobes & the lifter faces , timing chains & their camshaft teeth , timing chain & its guides , valve guides etc etc , its all oil film strength & only oil film strength ( nothing else)

How do we increase oil film strength with engine oils ?

Answer = increase the oil viscosity , say from 5w-40 to 20w-50 , if both oils have the same levels of ZDDP ( which they often do not)
So in effect , the lower the viscocity the lower the effective oil film strength

Then if the 20w-50 oil ( example only) is boosted with more ZDDP , say 1600 to 1800PPM , like some racing oils are , then the effective oil film strength is increased further & naturally racing oils have much lower detergent levels , so these oils must/should be changed ( oil drained) before every event/track day, the lower detergents reduce foaming ( very important )

So we / I find for a last century Porsche ( in this case a N A 968 ) , minimum viscosity 25w-60 racing oil & I mean minimum & an Oil Cooler that is at least 3 to 4 times larger than stock

And I do mean minimum

Maintenance } This is just as important to a 944/951/944S2/968 as the oil viscosity
Before we let any customers 944S2, 951, 968 hit the track for the first time , the sump comes off , remove the conrod bearing shells ( bigends) inspect & replace & new conrod nuts & sump gasket
You would be amazed at how many "street only" 944S2's / 968's & 951's we have had over the years that have mild to badly worn no 2 con rod bearing shells ( luckily we had changed out) & nearly went to the track with these worn conrod bearings , even the most fantastic race oil would not have saved them at the track , the above cars were running on low viscosity so called synthetic engine oils & being a sports car the owners had driven them in a sporty way on the road from time to time & the too lower viscosity damaged the conrod bearings at high core temp & at high RPM ( on the road)

Over head cams maintenance 944s, 944S2, 968 }
For these cars that go to the track , the cams to be removed before going for the first time & new inexpensive timing chain & the plastic / nylon guides fitted

Then every so many years the replacement of these same cheap items to be repeated depending on factors of how many sprint sessions per track day & how many days per year

MC 968CS

Fantastic response, thanks for that JET951.

333pg333

Bruce, MC is Mark C in PCNSW. You can see the 968 in his Avatar is pictured in the Eastern Creek garages beside Mark Phelan's old 996 GT3cs.

Mark, I'd be interested in what oil your workshop has been running in your car to date? I'd be inclined to follow Bruce's advice on these cars for sure.

OzJustin

Bruce - I have read a number of your posts concerning oil for the 944/968 platform over the last few months. You always provide thorough factual advice & this forum is lucky to have experts like you chiming in. If I ever get my hands on a 952 (on the hunt) I will certainly be following your advice.

Slightly off-topic -
I understand fresh rod bearings are key for reliable 944 Turbos running higher boost/larger turbos. What would be a ballpark labour figure for the bearing/sump freshen up you describe above? Feel free to discuss via PM.

JET951

Hi Justin , PM sent .

odurandina

it's that time again folks....

for road use....

one hell of a cold snap has us needing an oil that's under 400 weight at startup...

and the subject of the thread.

bump for the win.

RajDatta

Most here don't use their 968's as daily drivers and have them as their 2nd or 3rd car. You are one of the few who drives them all yr and live in cold weather.

67King

Dear God, please don't tell people to use this stuff on the street. Yes, I'm biased, as I sell a different type of oil, but go on their website. 500 miles, max. Why? Not because of detergent packages, its got gobs, about 2500ppm Ca, off of memory. It shears down. To get it to be a 0w50, they have to put tons of VI improvers in there, and those things shear down, unlike good, high quality base stock oils. I'll even quote from a different competitor: https://www.lnengineering.com/joegibbsracingoils.html

If you want to run a race oil on the street, stick with Millers, Motul 300V, or Amsoil Dominator. Most others either become acidic very quickly due to very low detergent packages, or shear down incredibly quickly due to use of VI improvers in lieu of good base stocks.

BTW......ZDDP levels in most race oils are on par with where they were when these cars were new. There is one exception, I forget if it is Red Line or Royal Purple. All others have sane levels which will take a long, long, long, long time to do any cat poisoning (which is, BTW, reversible, as the phosphorous will burn off if you get them sufficiently hot......such as on the track).

odurandina

show me proof there is all this VI in M1 0w50.

not trying to start a fight, but,

I'm fairly sure there is no basis whatsoever for such a claim.

and isn't the 500 miles max talking about weekend racing?

I'm fairly sure this high temperature oil can go quite a bit further in a street car.

Copilot

Bit of an amateur question here I'm sure - but seeing as the car I'm about to pick up is coming on 20 years old and I believe still has the stock cat... what's the worst that happens if I "ruin" the cat using this oil? Are we talking that it'll clog it, or just be ineffective... because we don't have emissions testing where I'm at... and after 20 years, the cat is probably pretty ineffective anyways right?

JET951

Cat converters are dirt cheap , where as camshafts & hydraulic lifters ,alloy cylinder walls / pistons etc etc are very expensive , even more interesting is that we have 1986 951's & 1986 ( quadcam) 928S models that we service that have been on a decent oil film strength oils ( 20W-50 ) since new( 27 years ) & there cats are still chemically working , admittedly these are not super high Km Porsche's but well over 150 Kms , so much for that myth

Remember in the owners manual that came with all these cars > 1995 968 + all the 951's , the owners manual states , from minus 10 deg cel to unlimited ( high ) ambient temps , use a 20w-50

A 15w - 50 is good down to minus 15 deg cel & nearly as good ( not quite ) in regards to sufficient oil pressure when the oil is above 90 deg cel

Note } these last century Porsche's with their high loaded flat tappet design engine must have very high oil film strength engine oils , and there is only two ways to do that }

A) increase oil viscosity , say from 5w-40 to a 20w - 50
B) increase ZDDP
If you do both ( 20w-50 + good levels of ZDDP ) = excellent oil film strength

We have tested the oil pressure of a 968 here at work with a 0W-50 only last month( workshop oil pressure gauge) & the oil pressure was much lower( at all RPM ) at 90 deg cel as compared to a 20w-50 , the reason we had to do the test is that the new customer had his oil pressure warning light flickering on at idle in heavy traffic conditions on a warm / hot day here in Sydney , and we thought he must of had a bad oil pressure sender unit until we tested the oil pressure hot & once we changer her back to 20w-50( from 0w-50) all was well , no further action required & oil pressure back to normal

Even surprised me , I thought that the oil pressure with the 0w-50 would of been sort of OK , but once again 20w-50 to the rescue , but then again it states that in the owners manual printed by Porsche when these cars were new

GianniGts

I m using 0w-40 on my 718 gts 2018 , i m going on track at lease one a month , would you recommend to use 0w-50 ?