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These numbers are optimistic, especially as cars age. The WSM states minimum 5 bar by 5000 rpm, which would be about 1 bar at idle hot. However, many 928's run much higher than that spec. Most cars running in summer heat with 50 weight oil are 1.5-2 bar idle and 5 bar between 3000-4000 rpm.
Well that's what my S4 (100k mi) and GT (300k mi) both do, using Mobil Delvac 5W-40. (Mobil Delvac 1 ESP 5W-40)
(It's a mixed fleet oil and conforms to the API CJ-4 SL/SM specs. The CJ-4 spec means the oil contains 1200ppm Zinc).
I've mentioned Delvac for the sake of completeness, NOT to start any fights, so ppl, please don't.
My GTS used Castrol Synthetic 10W60 in the hot Spanish summer and now in Bukarest too (eben hotter).
No annoying "check oil pressure" warnings at idle anymore.
No problem getting 20W50 anywhere out here in smog-land.
I bought a 5-qt jug and 3 more qts for a 944 oil change + top-off spare on Sunday at local Walmart.
But I don't care about any particular brand and do not subscribe to the Church of Syntheticology.
YMMV.
Originally Posted by Hacker-Pschorr
When was the last time you checked? Not even 6-7 months ago the 15/20w-50's were in stock and this past June they were all gone. This was at Auotzone, O'Reilly's, Advanced Audo and Napa. I talked to the manager at all four locations and they confirmed they were pulled from local inventory.
Even the locally owned franchise stores that carry Royal Purple, Kendall, and BP don't even have the 50wt's on the shelf anymore.
I will never use M1 15w-50 and I only go to Walmart when all other possible resources are exhausted.
O'Reilly's is usually my first stop, they had the thinner VR1 on the shelf an it was obvious by their display there was no longer an empty spot for the 20W-50
Stopped by after work and got 2 cases. Guy behind the counter said they had 176 qts at the warehouse.
I will let out a secret though. My local O'rielly's was willing to bring in some VR1 20w-50 from their Arizona warehouse where they had 276 Qts on hand
In NZ where temps range from 0 in winter to 30 degrees C in summer I use Penrite HPR5 5W40 (full synthetic). Porsche A40 approved. Been using it 3 years and no issues at all.
Lost count how many 928/s ( 1978-1995 ) we have had drop by ( never seen before ) in summer over the last 15 - 20 years with the engine oil pressure Warning light on at idle that have been on a 5w-40 engine oil here in Sydney Australia , then we put them back onto what the Porsche owners manual states in the "Look at Me " centre section of the oil viscosity page that states }
From Minus 10 deg cel to unlimited high ambient temps = use a 15w-50 or 20w 50 , from memory up to around 1981 it states minus 15 deg cel to unlimited temps for 20w50
Same goes for 911 > 1997 , 968 , 951 , 944 , 944S2 etc etc etc
Once we switch them back to what the owners manual states( 20w-50 ) the oil pressure WARNING light goes away ( funny that )
But then again we have had a lot of work from humans using way too low oil viscosities in last century Porsche's at our workshop and in the case of ( say ) a 5w-40 on a 928 ( all ) No 2 & no 6 con-rod bearings ( big ends ) destroy themselves at high RPM at normal( HOT ) operating temp , meaning No 2 & 6 starve first when the oil pressure is insufficient , its really quite good for business as we have a 951 at work at the moment that No 2 con-rod journal let go & it was on a way way way too thin engine oil for the oil temp at high RPM & we see time & time again on a 20w-50 we see no con rod bearing issues at high RPM
The other issue we have noticed over the last few DECADES is a clear link with camshaft lobe wear & cam chain sprocket wear on the 32 valve 928 engines and 16V 944 engines & when you think about it for just a minute it becomes quite clear why
With very low oil pressure at idle ( engine oil temp around 95 deg cel to 110 deg cel ) there is no where enough oil pressure at the oil pressure fed timing chain tensioners & consequently the timing chain is not held in tension and it starts to whip ( hence the noise ) that we hear when these engine are hot on a 5w-40 & naturally the hydraulic lifters start to bleed down a bit as well ( insufficient oil pressure ) , not as bad on a 10w-40 , but its still there , on a 15w-50 & better still a 20w-50 , there is no noise at all
The other area that's an issue with a "this Century " so called synthetic engine oil is insufficient oil film strength to protect the high loaded flat tappet designed over head cams lobes , these very last century ( sharp ) pointy lobes have NO OIL PRESSURE to protect them selves from the severe contact ( wiping loads ) against the hydraulic lifter faces & have to rely on Oil Film Strength ONLY from a splash of oil only onto this critical area ( hence why we see a lot of camshaft wear & lifter face wear ), but not with a 20w-50 engine oil that has as well decent levels of ZDDP
How do we get high oil film strength in an engine oil ?
Answer = Well its quite simple , if you have say two engine oils side by side , one is a so called synthetic 5w-40 & the other a 20w-50 & lets say they both have the same levels of ZDDD ( AW package which they NEVER do ) the 20w-50 has a massive advantage in Oil Film Strength because of the slight increase in its viscosity , so straight away the slight increase in oil viscosity increases Oil Film Strength in the 20w-50 over the 5w-40
But we know most 5w-40 & 10w-40( this century emission ) engine oils are simply not allowed to even have the same level of ZDDP ( AW packages ) that a last century oil viscosity engine oil like a 20w-50 engine oil is allowed to have , so now its a double WHAMMY , the 20w-50 has a much bigger oil film strength as compared to a 5w-40 this century oil
The last area that a concern , but not too much of a concern because we make a lot of MONEY out of it( when the WRONG OIL is used) , is with a 5w-40 engine oil in a last century 928 / 944 we see lots of crankshaft thrust bearing wear ( big money spinner ) , but on a 20w-50 we se NO ( repeat ) NO thrust bearing wear at all ZIP / ZERO , we have seen lots of 928S4's ( Auto's ) with their front Flex Plate deflected in to the MAX , but because they ( luckily for them ) they have been on a 15w-50 or 20w-50 we see ( after measuring ) the crankshaft axial play ( thrust bearing measurement ) is not worn at all
But if the said 928S4 was on a 10w-40 or a 5w-40 ( even worse ) the thrust bearing wear is bad to extreme & its so simple to understand because the ONE THING that protects engine thrust bearings is Oil Film strength
And because I have been warning humans about this stupid human inspired ( this century human thing ) being inflicted on last century Porsche's , meaning using way too low oil film strength & too low viscosity this century oils , I can not be accused of NOT WARNING them , because I have been warning them for YEARS & YEARS & we keep making way too much money out of this stupidity
I just hope we can reduce this madness a bit because we have way way too much work because of it & I really do not want these very nice engines being destroyed ( write offs ) because of this stupidity , particularly when the answer has been in the owners manual all along
Elephant in the room time } Has anyone ever wondered why a so called synthetic engine oil ( most are just Hydro-cracked crude oil, which I get a laugh out of ) that HAVE to use a bit or quit a lot of a LAST CENTURY DINO oil additive ( WW2 era ) called ZDDP , after the billions spent on advertising for so called synthetics ( hydro-cracked crude oil ) they have to add ZDDP to these oils , what sort of joke is that , why can't the so called synthetics stand of their own two feet and use NO dino additives ? , after all I thought the billions spent of advertising was trying to tell me how superior they are , but they only work with a last century additive
Answers quite simple } the so called synthetic can not keep metal parts that are under load / contact( like high loaded flat tappet wiping loads ) WITHOUT ZDDP
What A JOKE
Regards
Bruce Buchanan
Buchanan Automotive
Last edited by JET951; 08-10-2016 at 07:18 PM.
Reason: spelling mistakes
In NZ where temps range from 0 in winter to 30 degrees C in summer I use Penrite HPR5 5W40 (full synthetic). Porsche A40 approved. Been using it 3 years and no issues at all.
How on Earth would you know this? See the post below yours for a complete truthful post.
Stopped by after work and got 2 cases. Guy behind the counter said they had 176 qts at the warehouse.
I knew they had it in the warehouse since they still sell it online. Figures it's a local thing for the store shelves.
Oh well, after spending the better part of a day driving around GB trying to find 50wt I'm just ordering it from now on.
Originally Posted by fossberry
Porsche A40 approved. Been using it 3 years and no issues at all.
Whatever works for you is great - as per the owners manual the range of operating viscosities is a bit wide and can vary depending on conditions and driving style.
Threads like this are good for new people to get up to speed a bit since technology can change, formulas can change, and feedback from some of the engine experts can shed some light on a few areas.
On that note, has anyone been about to cough up a document showing the 928 engine is in fact A40 approved?
Specifications like this bother me, what changed with the engines Porsche was producing in 1984 on? I find it interesting that in 1984 the 3.4 Carrera replaced the SC, while the 944/928 engine remained unchanged.
It really makes you question the validity of such a standard for all Porsche produced after 1984, and not just the 911. The funny thing is, the air cooled guru's I know would never run 5w-40 in any 911 engine.
Originally Posted by SeanR
How on Earth would you know this? See the post below yours for a complete truthful post.
Remember this whole debate really got going when Doug Hillary suggested we all run 5w-40. I have nothing but respect for his testing and knowledge, but after a few of us followed his advice and experienced lifter noise on hot day, it showed just how much conditions play into these "known facts" that get tossed around.
08-09-2016, 08:41 PM
