KPV

I have been using Mobil 1 - 0W-40 oil for all of my oil changes but I am interested in increasing the bottom end a bit since I don't drive the car in the winter and I want additional start-up protection.

My thinking is that with a slightly higher low end viscosity, say 5W, there will be a little more residual oil left on all of the moving parts during startup.

Please enlighten me here. I was always under the impression that 0W is roughly equivalent to the viscosity of water as a reference. Am I all wet with this? If that is the case, upon shut down, I would expect much of the beneficial effects of the oil to drain off of the components that require them during startup! This is why I was thinking of going to a 5W. I feel it will cling better between startups and thus lower the wear rate.

With all of this said, I was looking on the Mobil site and they have the following oils in the Mobil One line:

• Mobil 1 0W-30
• Mobil 1 0W-40
• Mobil 1 5W-20
• Mobil 1 5W-30
• Mobil 1 10W-30
• Mobil 1 Truck and SUV 5W-40

If I were to choose, I would go for the Truck and SUV 5W-40 oil. Just because it markets the oil as "Truck and SUV" doesn't mean squat to me. It is 5W-40 oil. As long as it meets API SL/SJ requirements, I feel I am good to go.

I would appreciate intelligent thoughts on this subject. Please share............

KPV

http://www.mobiloil.com/USA-English/...s/Mobil_1.aspx

The "Truck and SUV" Mobil One 5W-40 oil can be found here.........

http://www.mobiloil.com/USA-English/...SUV_5W-40.aspx

Dock

Ken -

"0W" oil has a cold crank viscosity of 6200 mPa-s at -35C, and "5W" oil has a cold crank viscosity of 6600 mPa-s at -30C.

The 0W oil has a pumping viscosity o 6000 mPa-s at -40C and the 5W oil has the same viscosity at -35C.

I would think either 0W or 5W would leave enough oil clinging to the internal parts to protect the engine during the first few milliseconds of cranking, and that the 0W oil would flow quicker and provide better cold start protection.

JPschnitzer

I've posted on this subject before. I think it's best to stick with the factory recommended 0-40 Mobile One. Remember that internal stuff like the variable valve timing system works off oil pressure, so if you change spec, you might be asking for some problems.

KPV

Thanks for the replies guys.
With all due respect of course....
My understanding for the owner's manual recommendations is:

• It is for passenger cars that are driven on public roads, whether in Europe on the Autobahn or in the US on our 55mph roads.
• It goes hand in hand with the fleet import EPA restrictions and limitations in the US. I mean, if each car can attain a higher fuel economy, then PAG can import more cars and make higher profits. This is also the reason the cars are run leaner from the factory than would be prudent to extract the absolute optimum performance.
• They are recommendations for the 85th percentile or better that drive the cars factory stock shifting at or below 4,000 rpms.

My feeling is that a high horsepower 996TT that is driven on the track, with routine shifts at or near redline, should use a higher viscosity oil....say on the order of 50.

With that said, Mobil One makes a 15W50 oil. Since I never drive the car in the winter, I thought it would be prudent to use this in the car for the type of driving I do and the stress I place upon the car.

Does this change your opinions?

ebaker

Porsche says any ACEA A3 rated oil in 0w40, 5w40 or 5w50 is acceptable. If it gets below -12°F you're supposed to only use 0w40.

KPV

e,
Who makes 5W50? Where can I get it?

This is the only Mobil One oil I have found with 50 as the upper limit.
http://www.mobiloil.com/USA-English/...ce_15W-50.aspx

ebaker

There is a Mobil 1 5w50 available in Europe and Australia.

KPV

e,
What do you think of using Mobil One 15W50?

1999Porsche911

If you do a search, I explained my optinion and the reasons for not using 0w40 (any brand) in warmer climates. If you want to use it in the winter when normal temps are lower than 60 degrees, you will be ok. But if you are in warmer climates, or even cooler climates but get your oil temps run higher than 215 degrees regularly, stay away from the 0W40. In cooler climates, I would use the 5w40 or 10w40 and never anything less than 5w50 in summer. Preferably, 15w50 when temps are normally 80F and above.

I have run 15w50 for 50,000 miles in the summer months here in Chicago.

Joe Weinstein

Don't forget that flow relates to how quickly new oil
gets to the parts at startup too. Whatever remains
on a part from last night may be scrubbed off quickly,
so you probably want what Porsche tells you you want.
The idea of Mobil-1 truck oils is excellent if you can get
them in the correct viscosity, because some of the
beneficial additives in oil have been diminished recently
because of emissions concerns, not performance, so
other oils, like motorcycle or truck oils are freer to have
more good stuff.
Molybdenum is one excellent startup friction-fighter,
but is in few oils. In fact it causes loss of grip in motorcycle
wet clutches and starter clutches. Redline oil is among
those that do have it.
So look to additives, not viscosity change, for
startup/wear protection.
Also, viscosity does not equate with retention/binding.
Even if an oil is as thin as water (and I don't believe 0-weight
oil is that thin), the film retention (how much of a film
stays on a part), is very different. Oil won't dry off, and it's
affinity to adhere to metal surfaces is better and different
than water. You may be worrying too much.
Another game you might consider is that additives are
arithmetic, in that if you have 4 qts of zero-additive oil
mixed with 4 qts of X ppm of an additive, you end up with
8 qts with X/2 ppm of the additive, which may provide
much of the benefits of the additive. However, viscosity
is not linear, it's logarithmic, which means that if you mix
two viscosity oils, the result will be much closer to the
viscosity of the thinner oil than the thicker. Therfore, if
you put in, say 3 qts of 0-40 Mobil-1, and 5 qts of 5-40
truck and SUV, or even 2 and 6, you gain lots of the
additives, but keep the viscosity very close to 0-40 as
Porsche recommends, and as will be best for startup.
I think I'll start doing that myself.
Good thread, and thanks for the link on truck/SUV
additives.
Joe

ebaker

15w50 M1 came in my car new (2001), but now Porsche says not to use it. I've run a couple of quarts of 15w50in with the SL 0w40. I live in Texas. I wouldn't run straight 15w50 unless the start-up temperatures were always over 50°F.

KPV

Notwithstanding Joe's excellent discourse, it seems 5W50 would be a good compromise between the 0W40 and the 15W50.

So, the question remains, where can I obtain 5W50 in New Jersey?

KPV

1999Porsche911,
Can you please direct me to the thread which you reference. I would be especially interested in your opinions on the matter. Also, what is your background relating to this?

Dock

The high shear viscosity of both 40 and 50 weight oil is the same...3.7 cP at 150C.

In May 2000 Porsche released a Technical Information Bulletin for the 996 Turbo - it lists the following oils as the only approved U.S. oils...

Castrol/Syntec 5W-50
Mobil 1 0W-40 and 5W-40
Sunoco 5W-40
Havoline 5W-40
Valvoline 5W-30