Recent changes in the formulation of most commercially available motor
oils having raised concerns about continued use of those oils in 356
engines, the club invited Charles Navarro, president of LN Engineering LLC,
to come to one of our winter meetings and tell us what 356 owners need to
know about engine lubrication.
Charlie Navarro with the first slide of his PowerPoint presentation.
Charlie's presentation went into considerable depth, and we present only
the highlights here. His full statement on the subject can be found of
his company's Web site at
http://www.lnengineering.com/oil.html--where you will also find the oils
he recommends offered for sale. Note to club members: LN
Engineering will pay the Illinois sales tax and shipping charges for all
motor oil orders placed with them by Midwest 356 Club members. To take
advantage of this offer, you must place your order by telephone
(815-472-2939) and tell the person you talk to that you are a member of the
Midwest 356 Club.
API rating on an oil bottle label. CJ-4 and SM: not for a 356!
The problem.. The concentrations of antiwear
additives (primarily compounds of zinc and phosphorus) in motor oils have
been reduced in recent years. This has happened because car
manufacturers want to increase the interval between oil changes for new cars
and to extend the lifetime of catalytic converters (which they must warranty
for 8 years). Newer cars can do without the antiwear additives because
their engines use lower-tension valve springs that reduce the need for
boundary lubrication on the camshaft and cam followers. But Porsche
356 (and air-cooled 911) engines have very stiff valve springs and need the
additives. Use of the newer oils with API (American Petroleum
Institute) ratings of SM or CJ-4 in these cars can lead to camshaft failures
and expensive engine rebuilds.
The solution. Use a motor oil that contains the
concentration of antiwear additives required by an air-cooled Porsche
engine. Charlie recommends (and sells) two oils for the 356:
Brad-Penn Penn-Grade 1 Racing 20w50 Motor Oil and
Swepco 306 15w40. An alternative is to supplement a
regular oil with a product like General Motors EOS or STP 4-Cylinder Oil
Treatment, but Charlie cautions that getting good results with supplements
can be difficult because both the amount of supplement required and the
quality of the outcome will vary depending on what kind of oil you start
with.
General recommendations. Along with using the
right oil, Charlie recommends that 356 owners:
- Change the motor oil no more often than once a year, or every
2500-3000 miles for a 356 (5000-6000 for a 911), whichever comes first.
Change the oil just before you put the car away for the winter, because
letting an engine sit with dirty oil in it can cause trouble.
- Consider adding full-flow oil filtration to their 356 engines.
- Not use cheap gasoline. The off-brand fuels can have a higher
sulfur content and contain water.
- Use a fuel stabilizer if the gas in the tank will not be used within
one month.
- Change the oil after any use of a fuel system cleaner, so that any
residue from the cleaner will be removed with the old oil.