DonC

Hello everyone. I've been monitoring the board for about a month as I searched for a P car for myself. You provide a wealth of information on all aspects of owning a Porsche. I picked up a nice Grand Prix White 1996 Coupe last Friday and can't get enough driving it, it's addictive!

Question for the group--the selling dealer performed a 30,000 mile service before delivery. Work order showed oil as 5W30. When questioned, they replied that they were using that year round. In Albuquerque, in the summer! Any comments?

Regards,

Don

Robin 993DX

Don,

Im my opinion they should have used Mobil 1 15W50 in your car base on where you live.

Here are some more information on the oil viscosity I posted a while back on the old board.

What seems to be a simple answer is also one of the most complicated answer.
All of your thoughts are on the right track. Multi-grade oil was invented to
solve some of the problems in varying operating temperatures. So when you use
say 0W30 oil in your car it will be suited for the operating temperature range
you expected to be operated in. Now the different oil grades allows us to fine
tune the lubrication protection according to our driving habits, environment,
and temperature changes. For example if you live in California and drive your
air cooled Porsche everyday, use 15W50 all year round. I would think the water
cooled engine would use a different weight oil compare to an air cooled car in
the same operating environment because the water jackets would take most of
the heat away from the engine, in an air cooled car the oil is part of the
cooling agent so it will carry a lot more heat, thus you will need a heavier
weight oil for air cooled car. But say if you live in where I live where
winter temperature can range from 0 degrees F to 45 degrees F in a single day,
and since most my typical driving lasts about 30-45 minutes I use 5W30 in the
winter and when spring arrives I switch back to 15W50 because summer
temperature can reach upwards to the 90-100s F. I find going with the lighter
weight multi grade oil for winter the engine operates smoother when the car is
cold, and it seems to warm up quicker than the heavier weight counterpart. But
if most of your trip involves long distance driving and traffic jams where the
operating temperature can really heat up I would recommend you stay with the
15W50 oil no matter what. Also keep in mind that our engines were specifically
designed to have the highest tolerances possible after all the metal parts
have completely warmed up and expanded. The metal expanding factor is much
greater with an air cooled motors than the water cooled unit. Because the
engineers must factor in the fact that the air cooled motor will run hotter so
they would need to design in more room for the metal to expand, so that when
it is fully expanded it will form the perfect matching cylinder wall. I
believe that is why the air cooled 911 cylinder are sort of conical? Tapered?
So if you use a lighter weight oil you will have more oil seepage through the
piston rings when the engine is at a rest, which means you will see white
smoke more often during start ups. A characteristic of the flat engine design.
So in conclusion there is really no specific answer that will answer your
question. Like I said if you use your car moderately during the winter I would
change the oil to a lighter weight oil for winter and switch back to the
heavier weight during spring and summer month. If you race your car often and
drive it for long period of time I will just stick with the 15W50 weight all
year round. Unless you are a lucky Californian. But if you don't want the
hassle to change the grade of oil back and forth I would choose to use 10W30
in your situation.

Robin

[ 06-27-2001: Message edited by: Robin 993 DX In Atlanta ]

Robin 993DX

After that post, Dave from Redline oil shared some valuable testing data with me. Which I am sharing here with everyone. Of course the Mobil 1 oil is not avaliable in the 10W40 grade.

Robin,

I thought I would respond back to a note you posted a while bake on motor
oils, specifically 993 oils.
Some backround: these cars originally came with a 5W40 Mobil 1 oil not
available in this country, they now call for a 10W40 under all temperatures
in the US.

The viscosity in cSt of the (EU) 5W40 Mobil 1 is: 84 @40°C and 14.3 @100°C

The viscosity in cSt of the US Mobil1 15W50 is: 120 @40°C and 18 @100°C

The viscosity in cSt of the Red Line 10W40 is: 102 @40°C and 15.3 @100°C

The viscosity in cSt of the US Mobil1 5W30 is: 53 @40°C and 9.9 @100°C

As you can see the 15W50 is substantially higher viscosity than is called
for at low temperatures.
You can see from this why I recommend the 10W40 for all around use, based
on the viscosity Porsche calls for.

The 0W30 is a lower viscosity than I would recommend in most 993 engines
except at very low temperatures.

The oil in the air cooled engines as you say plays a big part in cooling
the engine, a lower viscosity will transfer heat better than a higher
viscosity. I wouldn't say that an air cooled engine necessarily needs a
higher viscosity.

Where your temperatures range from 0 to 45° during the winter, the 10W40
would be suitable as well as in the summer.

The cylinders are somewhat oval when cold, then round out at temperature. I
wouldn't expect much seepage past the rings when sitting, the oil in the
sump typically sits below the cylinders. I think more of the smoke is from
oil seeping down past the intake guide.

Regards, Dave
Red Line Oil

DonC

Thanks, Robin, I think I'll check with a couple of the independent shops here and see what they say. There's a fairly active group in the local region of PCA actively competing so there should be experience with the various oils.

I really appreciate your website. Great DYI information! Up until last fall I was a stone's throw from you in Dunwoody. I'm afraid I'm hooked on the climate and green chiles here, though.

Regards,

Don

Robin 993DX

So you were the one that threw the rock that hit my car!

I will be sending you the repair bill shortly...

LOL!

BTW, Why NM? Is that the next up coming growing city? My wife have been asking me to do some research to find out what is the next growing small city to move to, seems that Atlanta is gotten way worst in every aspect of living in the last several years.

Thanks

Clay

Hi.
I'm new here and I thought I'd jump in with some oil questions & info about a *possible* alternative oil for the 993. Mobil Delvac 1 5w40. http://www.mobil.com/mobil_lubes/ind...cts/index.html Under "products & applications" click on "synthetics" then at the bottom of that page click "Delvac 1"

I've been using this stuff in my 97 Jetta TDi
year round for the past 83,000 miles and I'm very pleased with it and I'm considering using it in my 993 (when I get one in a year or two ).

Why...With 13,000 miles on my Jetta I switched from Mobil synthetic 15w50 to Delvac 1 and my 1-1.5 quart oil consumption every 3000 was immediately cut in 1/2 and 83,000 miles later the car doesn't use any oil. I've also read that using an oil designed for diesels in a gasoline car can be benifical (particularly for higher mileage cars ) because of the added detergents in the oil.

Is there a reason why I shouldnt consider using Delvac 1 in a 993? How hot do oil temps
get in the 993?

Any fedback appreciated.

Clay

[ 06-27-2001: Message edited by: Clay ]