20W-50. At what winter temp. is it bad to start your 911 ?

[High Life]

I enjoyed reading this thread although I think a lot of postings are a bit off mark. I am no expert though - but please correct me if I am wrong: This is my understanding..

Viscosity is oil's resistance to flow. A high viscosity fluid is thick and does not flow easily. A low viscosity fluid is thin and flows much more easily. In engine oil, hot oil has a lower viscosity and flows more easily than cold oil.

Your engine runs over a range of temperatures from start up, through the warm up period and on to normal operating temperature. 90+% of wear is at the initial startup because oil is too thick (viscosity is too high). This is why its important to understand whether your in a heated garage or out in below freezing temps. Once started, however - this is a moot point as the engine is heating up.

The 2 numbers that everyone sees is derived from the SAE standards - seen in SJ300..
The first set of numbers is cold rating scale - W meaning Winter and the second set is 212 F - normal operating temp. (More importantly how the oil performs under Shear forces - HTHS)

Thus 0W-40 will have the same viscosity (high temp performance) as 5W-40 and 10W-40 at operating temp. The cold temp viscosity however is different.

The difference between the 2 numbers is achieved by using viscous modifiers in the oil- meaning that in a multi-grade oil like 0W-40 then you can have varying degrees of viscosity - thus viscosity can change via temp.

To correlate what diagrams are being shown in this thread - The lower the W (Winter) number the lower the cold operation and the higher the range the higher the second number.

So, It can be stated that the 0W-40 oil then covers the wide range of usage and the technical specs of our cars. Since 40 is the key number. Porsche's A40 list confirms this. (albeit "as of 1984") - They recommend both 0W-40 and 5W-40 from a variety of brands.

My understanding from reading through a variety of other threads (including bobistheoilguy forum) is that 0W-40 is a great range oil and the 40 will act like any other 40 oil (15W-40, 10W-40 etc) - but Porschafile's worry that the viscous modifiers will wear out and thus the properties of the oil will become too thin to protect the engine at operating temp (not cold temp). This is the issue with 0W - 40.. The durability of the modifiers. Change your 0W-40 oil often - and this should not be an issue.

Porsche even recommends (via sugarwood's post of his owner's manual) that 10W 30 and 10W/40 is acceptable up to -15F... (fuel efficient oil). I agree if you are using 20W-50 then I wouldn't be using it below the guide line.

In essence - if you plan on driving in below freezing temps - you look for a multi-grade oil that has a low W number (see posted charts).. Change the oil frequently so your oil protects at both low temps and at engine operating temps. My thought would be that 0W-40 would be just fine for starting your old Porsche in below freezing temps. Because it is the 0W that matters - The 40 is the number that will protect at operating temp (same as 15W-40)

[David Inc.]

Originally Posted by mickey356

I've said it before.....I never understand these threads... I just looked at the average yearly temperatures in Stuttgart Germany and it seems it gets pretty cold there in the winter, like many places here in the states. Did Porsche make and sell cars that could only be driven safely in mild temperatures?
I know, I know, there are temperatures where it's just plain hard on any engine, but why is this such an issue with viscosity...dino or synthetic...? I've never read the manual, does it say to change to different oil, or not drive below certain temps?

It's not that you don't drive it, it's that you would change to a lower viscosity oil for colder temperatures. I don't have the chart in front of me but you might be going from 20w-50 in the summer to 10w-40 in the winter (or something, you get the idea). The engine will still work, it's about maintaining proper lubrication.

[High Life]

Per Porsche Classic website in regards to their own oil..

Are the engine oils from Porsche Classic also suitable for winter use?
Both versions of the Porsche Classic Motoroil are multi-grade oils. They are suitable for both summer
and winter use. At temperatures below minus 10 degrees Celsius, Porsche Classic advises against
engine operation with 20W-50. The limit for the 10W-60 oil is minus 20 degrees Celsius.

https://www.porsche.com/international/accessoriesandservice/classic/motoroil-faq/

[manbridge 74]

-10C is 14F. Even the mothership confirms 20w50 for winter use excepting temps befitting Arctic regions.

[sugarwood]

Originally Posted by manbridge 74

-10C is 14F. Even the mothership confirms 20w50 for winter use excepting temps befitting Arctic regions.

Correct, do not use 20/50 below 15F.
Just like the owners manual says

[proporsche]

glad to see the final words..at least i know i was stupid and uninformed to use 20W50 going cross country in winter;-)What to expect from a California dude;-)..also i did not helped it when i gave gas and the oil was not warm.. yet;-)It was just my bad luck that night with a snow storm and 9F....looking back it was an adventure....i guess i was watching the Lakers and Celtics that night in the bar..not paying attention to the outside..
Ivan

[scarceller]

Trouble with reading the manuals from 1980s is that oils today have changed a lot and not always for the better. The new synthetic oils are really good but something often overlooked is the Zinc and Phosphorus levels, seems that since the 1980s these levels have come down considerably. Zinc is really good for mechanical lifters, especially the ones with rocker adjusters that are just simply pointy screw tips (ie: VW Bug Motors). The 911 uses a better foot-type adjuster but I think the zinc is still desirable.

I think any oil we use in these 911 Engines should have more than 1000 PPM (part per million) Zinc and more than 1200PPM Phosphorus. Here's the Mobile 1 spec sheet for all the Mobile 1 oils, take note that only a few at the end of the list have correct high levels of Zinc and Phosphorus.

https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf

One oil that's interesting because it has decent amounts of Zinc and Phosphorus while still being affordable is the 'Mobil 1™ Turbo Diesel Truck' oil.

And all the 'Racing' oils have high levels of Zinc and Phosphorus.

The other decent oil is the 'Mobile 1 15w50' it also is designed for mechanical lifters.

The 15W/50 oil is the most versatile as it has the best overall climate temps, good for 0-110 degree F climate temps.

[QueWhy]

I made the switch to M1 15w-50 last winter and have driven the car in single digit temps a couple times. No issues but I’m super careful to stay off the accelerator until it warms up a bit.

[scarceller]

And the added bonus of high levels of Zinc and Phosphorus at decent price point. Good choice!

Originally Posted by QueWhy

I made the switch to M1 15w-50 last winter and have driven the car in single digit temps a couple times. No issues but I’m super careful to stay off the accelerator until it warms up a bit.

[QueWhy]

Originally Posted by scarceller

And the added bonus of high levels of Zinc and Phosphorus at decent price point. Good choice!

The 5qt jugs at Walmart are by far the cheapest option, like $5/qt. I try to stay away from the place but will grab a couple every time I’m there.

[r-mm]

Originally Posted by QueWhy

The 5qt jugs at Walmart are by far the cheapest option, like $5/qt. I try to stay away from the place but will grab a couple every time I’m there.

+1 this and copious qty of rubbermaid plastic bins for parts organizing are my only reasons to set foot in the Big W.

[sugarwood]

Originally Posted by sugarwood

I don't understand why people mothball their cars all winter.
It rains all winter. Not a lick of salt on the roads since the last few days of rain.

In NY, December temps average about 40F.

Temps in Jan and Feb average 30F.
However, there are many days that are in the 40s
So, there are opportunities to drive one's car on clean rain rinsed roads.

By March, avg temp is back to 40F.

You can drive in Dec, find a couple of select post-rain days in Jan & Feb, and by March it's already time for DE!
So, there is really no reason to winter mothball the car in my part of NY.

Or just wait until it's 50 degrees out! Had a great drive today.

And yes, I am running 20W-50 all year round, since I typically don't drive it when below 40F
Reminder to self, 20W-50 bottom limit is 15*F
Despite switching over to M1 Synth 15w-50,
I will stick to 15*F as my cutoff.

Might be a useful reminder to anyone new.

Updating this thread for winter of 20-21.
Same logic holds.

These mild winters allow for 12 months of driving
and no need to put a car into storage.
Salt is washed away since every month now has rain.

Have had several good drives already in December.
Today was almost 60 degrees in NY.
Great day for a drive and a hike.

Let's see if January brings rain and a 40F+ day.

[kach22i]

The 15W/40 I put in just before winter storage is maybe a little noisier than 20W/50 but I plan on getting it out of the barn in early as possible this spring to work on it.

Can one hear a difference in oil viscosity?

I think I can, but I'm not sure what it means.

Going back to 20W/50 ASAP.

Regarding salty roads, in Michigan only a fool would risk winter driving in my opinion.

Regarding tires, not good to run summer tires in the cold, they don't grip worth squat and are dangerous. All Seasons aren't all that much better- snowflake symbol or not.

[sugarwood]

Your area may be colder than mine.
But, you may have a break with the oddball 40F days

Here, winters have become moderate with sporadic rain. Salt is washed away by rain.
There have been warm days with rain washed roads in every winter month, in my area.

Summer tires are fine about 40-45F, but you can go lower. Just don't drive like a maniac in winter.
The point is not to drive like a track event, but merely to take a drive to operating temps

Cars don't like to sit for 5 months, and today that is a choice some no longer have to make.

[TubbyAZ]

Originally Posted by universeman

It is a great heater for temperature, but it makes a dry, smelly heat that is off-putting. Don't get me wrong I love everything about the 911 but let's be honest here. The heater makes the car smell like oil. Electric seat heaters are IMO the best for quick heating.

Wind in my hair –
Shifting and drifting –
Mechanical music
Adrenalin surge –

Well-weathered leather
Hot metal and oil
The scented country air
Sunlight on chrome
The blur of the landscape
Every nerve aware

-Neil Peart

[VFR750]

Rebuilt engine without significant leaks = heat that doesn’t smell. It is possible.

18,000 miles on the bottom end. Only significant leak was blowing the RMS on a << 15F morning with 20W-50 dyno oil.

[sugarwood]

Same goes for 2021-2022.
Isolated 50 degree days and rain to wash the salt in Jan and Feb.
give you an opportunity to drive at least once a month through the winter.
These are 12 month cars now.
No need to mothball due to warm winters now.

Originally Posted by sugarwood

I don't understand why people mothball their cars all winter.
It rains all winter. Not a lick of salt on the roads since the last few days of rain.

In NY, December temps average about 40F.

Temps in Jan and Feb average 30F.
However, there are many days that are in the 40s
So, there are opportunities to drive one's car on clean rain rinsed roads.

By March, avg temp is back to 40F.

You can drive in Dec, find a couple of select post-rain days in Jan & Feb, and by March it's already time for DE!
So, there is really no reason to winter mothball the car in my part of NY.

Or just wait until it's 50 degrees out! Had a great drive today.

And yes, I am running 20W-50 all year round, since I typically don't drive it when below 40F
Reminder to self, 20W-50 bottom limit is 15*F
Despite switching over to M1 Synth 15w-50,
I will stick to 15*F as my cutoff.

Might be a useful reminder to anyone new.
Updating this thread for winter of 20-21.
Same logic holds.

These mild winters allow for 12 months of driving
and no need to put a car into storage.
Salt is washed away since every month now has rain.

Have had several good drives already in December.
Today was almost 60 degrees in NY.
Great day for a drive and a hike.

Let's see if January brings rain and a 40F+ day.
Updating this thread for winter of 20-21.
Same logic holds.

These mild winters allow for 12 months of driving
and no need to put a car into storage.
Salt is washed away since every month now has rain.

Have had several good drives already in December.
Today was almost 60 degrees in NY.
Great day for a drive and a hike.

Let's see if January brings rain and a 40F+ day.

[VFR750]

Agreed

Drove it in December. 15w-50 M1

Dead battery in January stopped me.

Now is the opportunity to rebuild rear calipers.

[Schulisco]

This is the excerpt of the Porsche Manual of an '82 SC, this should clarify that the usage of an 20W50 on outside temperatures of 15°F / -10°C is still okay, nevertheless - I you plan to drive it every day / regularly on such outside temperatures I would take a lower Winter visosity like 10W - all depending on your wheather / temperature conditions over the whole year...

[cmcfaul]

I find oil pressure to be a bit too high using 20/50 (Mobil v-twin) in the winter and add a couple qts of 5/20 or some similar thinner oil. Any downside to doing this?

Chirs
89 Carrera