JBO

According to the PCA tech advisor, Porsche now recommends 0W40 M1 for all 911's, even the older ones. The PCA tech advisor says this is what he recommends for use in an SC. I have been using 15W50 M1. Steve W. and Peter - what do you think?

Edward

You can check the archives on the 993 board ...been discussed prety thoroughly just recently, and some time ago. Off the top of my head, I can't recall if Peter had posted, but Steve had responded.

Edward

Steve Weiner-Rennsport Systems

Porsche recommends the 0w-40 due to the Variocam variable valve timing hydraulics in the newer engines. Heavier oils play havoc with that equipment and it will not work correctly.

Expediency being what it is and the desire to stock one oil,.......dealers use the 0w-40 in everything.

For the air-cooled 911's being operated in climates above freezing, I think the 15w-50 is a better choice. If one drives his (her) car in the winter where below-freezing engine starts will be anticipated, then the 0w-40 will work.

Just my opinion of course. Ultimately, its your motor and you can use whatever makes you happy.

JBO

.....but Steve I won't be happy unless you approve...

der Mond

I have done what Steve has recommended for the past year and a half in my '87 3.2 with good results. I've used 0W-30 synthetics (Mobil1 and Amsoil), and now 0W-40 since they appeared in a Honda Civic Si, Dodge Dakota 5.2 and Jeep Cherokee 4.0 with excellent results - the Honda with 282K miles used normal amounts of oil until a moose ended its life. I found that the lifters in my Cherokee pumped up quicker with Mobil1 over Amsoil for some reason, so I practically own stock in Mobil. Some wrenches insist that you need 50 weight oil in a 911 all year round no matter what, but I have been convinced that synthetics pretty much prevent metal-to-metal contact, and it's sure a good idea to get the oil flowing as fast as possible on cold startups. When I switched my 3.2 at 119K miles from Castrol dino oil to Mobil1, I got increased oil seepage from the flexible lines, and when I first switched to 0W-40 for winter I needed to replace my worn top internal thermostat o-ring seal. I get a bit of seepage now but consider it a small price to pay.

RicoJay

Castrol GTX 20W-50 is suitable and recommended by Castrol for any ambient temperatures above 20degF. Those of you in Alaska or the NE may need to think about lighter oils and the possible seepage that comes with it, assuming you don't have a heated garage for those morning starts, but here in Memphis it's only about 10-20 days per winter where the low temp is lower than 20degF. I would feel very comfortable starting my car with 20W-50 on a 10 degree morning provided I baby the engine for the first 5 minutes of driving.

Gordon Attar

DOnt do it use a 15W/50 Semi Synthetic in older vehicles as recommended in the early 90's when it was relavent

Brian_77_3.6

Porsche now says that air cooled engines run cooler with the 0-40 Mobile 1. I have been using it in my 3.6 and I agree that it runs a few degrees cooler but I am experiencing seepage when the car sits for a week or 2.

Doug Hillary

Hi,
Porsche do recommend either a 0w-40 (below -25C) or 5w-40 Semi synthetic or fully synthetic oil for all post MY73 engine families. Both of these oils are SAE40 oils at 100C - only their characteristcs at very low temperatures are different

An important part of their recommendations is that the oil is Approved and Listed as part of their protocols. Some of their test protocols follow on from the ACEA A3/B3 tests regading viscosity retention and anti foaming abilities for instance. Porsche do not recommend any oil with a High Temperature High Shear viscosity below 3.5cSt

Regarding Mobil 1, their 0w-40 (HTHS vis 3.6cSt) and their T&SUV 5w-40 (HTHS vis 4.1cSt) are very different animals and whilst not Approved and Listed the 5w-40 oil is a wonderful product

Heavier oils (the only SAE50 oil Approved and Listed by Porsche is Mobil 1 5w-50) do have a downside in some engines. They do tend to run somewhat hotter in air cooled engines

When changing from a mineral oil to a fully synthetic oil (of similar viscosity) it is quite common to lose some oil pressure at idle. This may be up to one bar. This is due to the superior flow characteristics of the synthetic lubricant

IMHO using an oil that is NOT Approved and Listed by Porsche is a false economy

There are no "magic" oils and oils that meet similar specifications have the same end results. Some oils tend to keep engines cleaner than others - Mobil 1 is one of these

I hope this helps
Regards
Doug

JTM

Hi Doug,

After a brief absence from Rennlist and that lube site, thanks for weighing in. Although I'm not here much, I've always valued your air-cooled lubrication opinion and always look forward to your comments. Glad to see your post!

Best Regards,

JTM

ked

I'm "sticking" w/ Mobil1 15W-50 in my 109K mi '87 Carrera. Been satisfied since I switched over @ 75K (previous owner loaded Castrol 20W-50). I think Doug meant "15w", not "5w" - I know of no 5W-50 grade M1. Through hot & humid southern summers w/ AC on full blast, I have not had a temp problem.

I am not going to switch to a narrower-range weight synth oil, as long as I don't use the car under very cold starting conditions. I believe that a "modern" (as in to match the tolerances required for specific engine component design reasons, & tradeoff improved fuel economy via thinner oil (less internal mechanical friction) for potentially greater engine wear) oil is not necessarily the best solution for a pre-90s 911 w/ 100K+ miles, just because PAG or PCA say it is acceptable to use.

I would be curious what Pete & Steve think of this pov (if they aren't tired of talking about oil yet).

JTM

Perhaps for your application, M1 15W-50 is the best choice. It is certainly very popular, particularly for track use. However, I believe Doug was simply pointing out that M1 15W-50 was not an approved Porsche viscosity. A quick review of the approved oils in Porsche Tech Bulletin of 5/23/03 lists a M1 5W-50 which I believe is not available in the US. Although listed as being available worldwide, I've never seen it in North America.

DarrylH

Not to restart the Castrol vs M1 debate, but isn't Castrol Syntec 5W-50 on Porsche's approved list, if you feel you need the 50-weight?

ked

Indeed, here is what I found on Mobil's Aussie website...
"Mobil 1 5W-50 - Driving Excellence
Helps keep your engine running like new. Its unique formulation helps extend the life of your engine by reducing oil breakdown.

Mobil 1 15W-50 - Race Proven Performance
Designed for turbo and supercharged engines particularly at high-speed under highway, towing and other severe service conditions. Higher viscosity is ideal for use in older engines."

While I'm sticking w/ 15W-50, seems 5W-50 would be great for driving through cold winters in the Great White North - I wonder if it is marketed there (& Alaska)?

I somehow thought that PAG & PCA had endorsed M1 15W-50 in past years, for older, higher mileage 911s, perhaps I was wrong. Cheers!

DarrylH

Nope, not that I've been able to find. Dunno why, it seems a natural for the climate, as you say; Toronto has temps from -25C to 35C over a typical year, many places an even wider range. (I've gone with the Castrol Syntec, in spite of some questions about it, I figure it's better than the dino...)