Doug Hillary

Hi,
Mobil 1 5w-50 is widely available outside of NA and has been the prime seller here in OZ for many years. M1 15w-50 has only recently rejoined the M1 lineup here and is not marketed widely except for motorcycles

ked - the advantage of the lower viscosity (0w or 5w) over others is the oil's ability to circulate faster and there is some evidence that this may reduce engine wear. Most wear occurs during the period taken to get the lubricant's temperature to around 65C when the "serious" anti-wear" (AW) additives are activated

DarrylH - Castrol's Syntec 5w-50 is not Porsche Approved and is therefore not Listed. Castrol have one 0w-40 oil and five 5w-40 oils Listed world wide

The Approval and Listing of lubricants by engine Manufacturers has its foundation in the 1930s. Caterpillar was one of the first and thei system is still in place today. Most German engine makers have had their own Approval systems in place for many decades and one at least (MB) for more than 60 years. This is a wise and sensible approach to a very complex subject
This transcends the API (Oil Industry controlled) quality standards and the ACEA (formed in 1994 or so) is the umbrella body of all Euro vehicle Manufacturers. Porsche's Approvals go beyond the ACEA quality standards in ceratin significant areas

Castrol's Syntec is a Group 3 semi-synthetic oil (the minimum for Porsche's testing) - newer Group 3 semi-synthetics rival the overall performance of the more expensive Group 4 and group 5 fully synthetic lubricants. Some Castrol lubricants (mainly mineral but some synthetics too) have acquired a reputation of forming internal varnish deposits and in air cooled engines this can raise operating temperatures
Castrol have always had a great range of lubricants (I have worked with Castrol in lubricant development since 1980) but this has been changed somewhat since the BP buyout some several years ago

Lubricants meeting Porsche's Approval and that are Listed will perform very much the same regadless of the Brand. The correct viscosity is important however

There are no magic oils of any type regardless of the advertising hype or "testimonials"

Regards
Doug

ked

"the advantage of the lower viscosity (0w or 5w) over others is the oil's ability to circulate faster and there is some evidence that this may reduce engine wear."

Doug, great "just the facts" & technical context on oils for our old air/oil cooled powerplants. I feel I should be pestering Mobil on these further inquiries, but you are more timely, if not more objective.

- is a lower numerical rated oil (5W- / 15W- etc, same brand / manufacturer) any different from one another OTHER THAN the temp-related specification at which the oil maintains equivalent viscosity?

- if you don't start your engine at a temp BELOW the lowest temp for which your grade is rated, is there ANY advantage to using an even lower viscosity grade?

- is there any operational scenario (duty, environmental, etc) for which a lower viscosity rated oil (0W- 5W-) is NOT preferable, or may even be a bad thing?

- if 0W-, 5W- is the trend in techncial improvement, can we expect to see -5W- or -10W- in the future?

- I have heard that Kendal GT-1 has been reformulated in the past few years. It has been a longtime favorite of mine for my 356s, among "Dino" (non-synthetic) oils (along w/ Shell Rotella T). Do you know anything about changes to this niche American oil?

I really appreciate you sharing your expertise w/ us... Many thanks in advance.

Doug Hillary

Hi,
ked - some info for you;
"- is a lower numerical rated oil (5W- / 15W- etc, same brand / manufacturer) any different from one another OTHER THAN the temp-related specification at which the oil maintains equivalent viscosity?"

The answer is maybe! For instance M1 0w-40 is a different formulation than say M1 15w-50 - as is M1 T&SUV 5w-40 (nearly Delvac 1 5w-40). Another indicator is the oil's Viscosity Index (VI) - this number represents the lubricant's viscosity change from one temperature point to another. This arbitary scale indicates the variances as temperature rises/falls - the higher number indicates less actual change from one point to another (with engine oils this is typically from 40C to 100C but can be at any point)

" - if you don't start your engine at a temp BELOW the lowest temp for which your grade is rated, is there ANY advantage to using an even lower viscosity grade?"

Not really - well not a significant one anyway. The less desirable situation is to use a much heavier oil (for instance a 20w-50 or 25w-50 mineral oil) than is needed - this dumps oil out of circulation via the OP relief valve and keeps some oil out of filtration longer due to the differential bypass within the full flow filter. Generally I think Porsche have it right at 0w below -25C and 5w above. Porsche have factory filled with synthetics since 1991-2 - firstly with a 10w-30 and then a 5w-40 (both Shell) - it is now M1 0w-40. They have a LOT of experience as does MB!
Remenber that oil in normal use operates at about 90-105C. At 90C a (5w)-40 lubricant is actually functioning at the viscosity of a (5w)-50 lubricant (the oil has the same viscosity as a SAE50 at 100C)

"- is there any operational scenario (duty, environmental, etc) for which a lower viscosity rated oil (0W- 5W-) is NOT preferable, or may even be a bad thing?"

Not really. Some engines do sound noisy at startup with a 0w-?? oil for 5-10 seconds or so. There are many reasons for this - one is simple acoustics! For most Euro manufacturers the viscosity of the oil at 150C is critical. This is called the High Temperature High Shear (HTHS) viscosity - Porsche's Approval protocols take the ACEA tests to a higher level of performance both at 100C and at 150C
The best thing for any engine is to get the oil's temperature up above 60C as quickly as possible and then try and keep it below about 120C (synthetics)

"- if 0W-, 5W- is the trend in techncial improvement, can we expect to see -5W- or -10W- in the future?"

I don't think we will see minus numbers. 0w lubricants are rated as having around a 30% lower viscosity at -30C than say a 20w at -10C. Factor into this the latest base oils and additives and modern synthetic oils typically have a pour point down to -54C (0w) and -45C (5w)
It is interesting to note that M1 15w-50 has a pour point of -45C and Castrol's Formula "R" synthetic 10w-60 a pour point of -42C!

"- I have heard that Kendal GT-1 has been reformulated in the past few years. It has been a longtime favorite of mine for my 356s, among "Dino" (non-synthetic) oils (along w/ Shell Rotella T). Do you know anything about changes to this niche American oil?"

No, I know nothing about Kendall's lubricants except that their Gt-1 synthetic 5w-40 is Approved and Listed by Porsche.
Shell's range of diesel oils Rotella etc were once Porsche's mainstay! They always recommended a "mixed fleet" HDEO Diesel/Petrol rated oil for the early aircooled engines. I had more success with these and the Delo oils in VWs in Europe where sludge and shearing were real problems. I have used these HDEOs ever since - now as synthetics

Personaly I like a 5w-40 oil over a 0w-40 oil in the correct environment of course and I will never use any oil with a HTHS below 3.6cSt or above 4.5cSt in normal use

I hope this is not too long winded

Regards
Doug

S2TGART

Everyone seems to make picking an oil, a major event. Just use what was recommended in the owner's manual. My '83 SC engine has Shell Oil stickers on it and I have read, that was the factory fill, Shell 15W-40. I don't see how Porsche can now say use Mobil 1 0W-40 instead. Mobil 1 was around in the 80's, what makes it so special now, that they didn't factory fill it back then? I understand the need for the thin stuff for the newer engines with vario-cam systems. However, the old 3.0 engine called for 15W-40 for temps down to 5 degs. 10W-40 for temps down to 5 below 0. How many of us will be driving our cars in temps that low?
Per my owner's manual the recommended weights are regardless of dino vs. syn. Pg 85 "Engine Oils-petroleam based and/or synthetic based"

Again, synthetic oil exsited in the 80's. Why didn't Porsche recommend it then?

DarrylH

I know you've forgotten more about oil than I'll ever know (I mean that as a compliment!) but oddly enough, 5-50 Syntec is on the approved list with US, CDN, MEX beside it. Isn't that strange? At least, there's a post here in which JasonAndreas reproduces a list https://rennlist.com/forums/showthre...t=approved+oil - post 23 in the thread (dunno how to reference just a single post from a thread.) It 's not considered to have good light running properties, whatever that means. Wouldn't 5W pretty much imply good light running?

Doug Hillary

Hi Darryl,
the referenced list is outdated by some years - probably five or six. Porsche will delete oils from their List as they become unavailable/discontinued/reformulated and etc, or, in the light of warranty/user experience

As for "light running properties" the oil is actually a SAE50 oil - the 5w only applies as a lower reference point and not at normal operating temperature. Any SAE50 oil is quite viscous and this is the highest viscosity oil ever recommended by Porsche

In the US of course CAFE has mandated oils such as 0w-20 or 5w-20 - these oils are unsuitable for use in non compliant engine families. Ford, GM and Honda and some others selectively use these lubricants. In the correct application they have shown good in-service durability and engine component life appears to be excellent too

As a matter of interest, 1941 US cars were using SAE10, SAE20w-20 and SAE30 oils - in wnter 10% kerosine was added too! It is not so long ago that many German cars used SAE20w-20 or SAE30 lubricants. Modern lubricants are a wonderful testimony to the Chemists and Blenders and the now forceful requirements of Bodies such as ACEA

Oils with poor flow characteristics (most mineral oils) and a high HTHS (above 5cSt) such as some ?w-50 and above viscosities can slow turbochargers etc and as Steve mentioned, some modern engines have many hydraulic functions and phasers etc that depend on a reliable engine viscosity at all the operating temperatures likely to be encountered
In OZ Subaru has some difficulty convincing certain dealers to use energy efficient oils - use of too viscous lubricants had resulted in some complaints of poor performance with the WRX and other turbocharged engine installations

M1 0w-40 (the subject of this thread) seems to be an extraordinary product and is favoured by many engine makers. Other brands of 0w-40 lubricants like ELF, Motul, Shell, Castrol and etc are excellent products too

I did not intend to dominate this thread - sorry if some see it this way

Regards
Doug

DarrylH

Thanks for the clarification. I can't imagine anyone fretting about your input to this thread!

ked

Doug, I concur w/ Darryl - keep pouring it on - & thanks for the cogent response.

Steve Weiner-Rennsport Systems

Gents:

I'd just like to add a few things on this subject.

The operating conditions inside an air-cooled and water-cooled engines are very different so the demands on the lubricant are not the same. In some cases, whats "good for the gander, might not be good for the goose,".......... Oil temp control is much tighter in water-cooled engines and they tolerate low viscosity/ultra thin oils much better than their air-cooled counterparts.

Also, its important to understand that on 911 engines, the oil temperature sending unit only samples temperature at ONE point inside the engine and there are places that are far hotter than you see on the guage.

Doug Hillary

Hi,
Steve - you touch on a number of interesting points. Not all coolant cooled engines tolerate ultra thin lubricants either however and ACEA has special Quality Categories for such lubricants. These lubricants should only be used where recommended by the engine manufacturer - and that is NOT in any Porsche engine!
Coolant cooled engines typically have a hot operating oil temperature 10-30C higher that the coolant

a) Porsche no longer have any Approved/Listed ?w-30 lubricants

b) The reasons for a) relate to the difficulty in maintaining the 150C HTHS viscosity above 3.5cSt with SAE30 lubricants. Porsche's test is 120hours!

c) Porsche's Approval protocols also cover additional volatility rate testing (NOACK test regime at 250C)

d) Typical major component operating temperatures will be in the order of 200-450C but they are designed to survive at these temperatures. The oil must be too!
For instance it takes oil up to 4 minutes to enter and exit the ring pack area depending on viscosity and composition (mineral/synthetic)
Oils that have good flow characteristics dissipate more heat (heat flows from the hotter to the cooler medium) quicker - a distinct advantage in an air/oil cooled engine. Porsche use a generous sump capacity to assist this process too

e) Most engines with oil temperature monitoring devices (gauge or ECM) sense from one critical point. The time the oil spends in the oil pan/sump/etc is a factor but Approved synthetic oils will tolerate temperatures between 120-130C for long periods without harm

d) Porsche's anti foaming test protocol is extremely important. Many regular oils may fail such a test within a short time frame and regardless of the oil's viscosity

Anybody using a ?w-30 lubricant in their MY73> Porsche should seriously consider moving to a ?w-40 Approved and Listed lubricant at their next scheduled oil change - or sooner
(Monograde SAE30 oils used in older 4cylinder engines excluded according to temperature)

Steve - I love Portland and Oregon! It is many years since I last visited there but it is a lovely place and a beautiful State!

Regards
Doug

Edward

Succinctly put, Steve.
...And IMHO, PAG has all but completely ignored the gander in favor of the goose/geese that currently are laying their golden eggs.

Steve, can I ask a few questions on what you just raised:
- Where in the engine is that oil temp sample point?
- Is it after the oil has returned from the front cooler?
- What is the "typical" (if there is such a thing) difference in temperature from that sample point and, say, the areas around the pistons/comb. chamber?

Thanks!

Edward

Steve Weiner-Rennsport Systems

Hi Doug:

Thanks for your VERY detailed and informative posts.

Speaking for the Rennlist Community, these are precisely the kinds of things that add SOOOO much value to the RL experience and I appreciate your valuable contributions.

Indeed, Portland is a beautiful place and I'd be pleased to buy you a local brew (or two) on your next visit,...


Hi Edward:

Without question, Porsche's actions & practices over the past 4 years have made it abundantly clear that the air-cooled community has become "persona non gratis" regarding parts & service.

Engine temps are sampled at different places in the different engines. 2.0 to 3.3 engines are sampled at the rear of the engine next to the fan; 3.6's get sampled at the front right by the pressure sender. Its after the oil emerges from the engine cooler or filter, as the case may be.

I've observed as much as a 40 deg F spread between the guage's readings and other sampling points in the oil galleys so the guage represents an average, not a peak reading to me.

Edward

Steve,

Thanks for the specifics! As much as a 40deg diff ...wow! This is good to know, especially when the guage "only" reads at 9:00
Thanks again for all you do, Steve!!

Edward

JET951

hi
little bit of my history before i give you my findings.
MY name is Sean Buchanan, i work with my father Bruce Buchanan who has been working on porsche cars since 1977. I started as an apprentice and now six years later i am a qualified motor mechanic specializing in porsche. (all models)
you must excuse me as my post will not only deal with just 911s but all porsche cars of the era.

lets start with the early 944 single cam, twin cam engines. we have heard over the past six years of a lot of damage and worn engines and have noticed a pattern emerging that is a real pitty and completely unnecessary.

we service and maintain a lot of single and twin cam 944 models and we have had no engine wear at all when using a grade of oil that these engines were designed to run on. remember the 944 single cam was based on the 928 that was released in 1977 and early design work for these motors were in the late 60s early 70s.

we have read of lots of twin cam 944 models with worn cam lobes, lifter faces and mainly cam chain sprockets and chains. remember these surfaces are not pressure feed with oil, its only splash, and we have had NO wear problems with our customer cars with well over 250 000km's running on a
25-50 oil.

Simon Greenwood, a good friend of ours, who owns an indipendant porsche repair workshop has, at this moment, a 1989 944 turbo that the owner has been running a 5-40 synthetic oil(changed every 8000km's) for the past 30 000km's and all 4 cylinders and pistons are worn out. simon has had the engine bored out to accept oversize pistons and advised the customer to run a 20-50 or 25-50. this vehicle is running standard boost and had only 120,000km's.

A perfect example of this modern day sympton of using oils that simply dont work in the long run is 928 thrust bearing wear, this is a very new problem to us. and we have been working on 928s for a long time.a check we have been doing for a long time is as follows...

928 thrust bearing clearence check(axial play) 928 all models. using dial guage since may 04 to november 05

in this time we have had 52 new customer and pre purchase inspection 928s(all models) come into our workshop. the total number where it can be determined that the engine had been running on a 5-40 or lower viscosity oil was a total of 31 vehicles.
of these 31 cars all of them are on or exeeding the spec clearence. 2 of these cars are on their wear limit and will have to be dismantled very soon and be rebuilt and both of these had done approx
80 000- 100 000km's on these thin oils.

928 customer cars that we know and that have serviced for years and have been running on valvoline GP50( formally know as turbo V) 25-50, 42 cars in all most with 150 000km's and above were all within spec. (actually low to midrange wear)
the spec for these cars is 0.06-0.192mm = within tolerance
0.40= wear limit

911 3.0litre 3.2litre 964 3.6litre...
we have noticed that if 964 or ealier 911 models arew driven in city conditions with an oil which is less than 15-50 then oil pressure at idle when hot is nearly always too low and valve guide wear occurs in less km's. and on a 5-40 oil the engine is noticably mechanically noisier and causes oil leaks faster then a thicker oil.

928 all models...
5-40 oils= engine noticeable noisier, valve guide wear increased, cam chain sprockets and chains and lobes(twin cam) excessive wear, thrust bearing wear excessive.

this is not a complex subject like some people make it out to be. for example: any engine running at idle has pressurized oil running through the crank into the main and big end bearings. Now the only substance between the bearings and the crank(say main bearings) is the pressurized oil, when that oil looses too much oil pressure( such is caused by too thin a oil for the application or high load or mechanically over revving) it will cause the bearing to come into contact with the crank...thats metal to metal... which means Spun Bearing(damage). we have heard of a few 964 having this problem.

remember this is only my and my fathers opinion and we work six days a week on porsche motor cars. and these are facts. this is what we hav seen and experienced. to me the solution is clear. but it is your cars we are talking about, and thats your decision to use which oil is best.

thankyou for reading,
Sean Buchanan

der Mond

Sean,
My Honda Civic, Dakota and Jeep may have been fine on lower viscosity synthetics in winter but you have convinced me to change out the 0W-40 in my '87 Carrera in favor of 15W-50. I can't thank you enough for taking the time to share your extremely valuable experience, and as has been said already, this is what makes the Porsche forums so immensely helpful. Thanks again...
Dennis