From the DeTomaso BB:
I had an auto repair shop in Houston, Texas, which happens to be the
petrochemical capital of the world. I have had many conversations with
Chemical engineers at oil companies as well as Forensic Chemists at analysis
laboratories. I also performed EPA and DOT conversions on European Gray
market cars in the 80's. These cars had to pass rigid emission testing at
federally approved testing labs. I have also spoken with automotive
engineers for Ford and Chevrolet. So forgive me for being soooooooo
opinionated about this subject matter.
There are two schools of thought regarding multi-grade motor oils.
First school says, multi grades make engines last longer because they
circulate quicker at start-up when most of the engine wear takes place.
Second school says, straight grades make engines last longer because they
have better shear characteristics and do a better job of lubricating the
rings, which makes them last longer.
Both of these schools have error in thought and implementation and don't
address all of the aspects of the oil.
I maintain a third school of thought, which says a clean engine is a happy
engine.
I use Delo 400 30W by Chevron. It has all of the ratings including diesel,
gas, and turbo. This motor oil is not advertised at racetracks and other
than truckers; nobody knows what the hell it is. According to the engineers
at Chevron, Delo has the highest level of detergents and dispersants of any
motor oil. This means it will keep a motor clean and/or clean a dirty motor.
18-wheelers that have diesel engines with turbochargers and superchargers
use this oil.
So here is the poop. Multi grade motor oils are made from low grade crude.
The are man-made molecules created in a cat-cracker, short for catalytic
cracker - a chemical reactor for converting oils with high boiling points
into fuels with lower boiling points in the presence of a catalyst. These
manmade molecules break down faster and create more deposits than the
molecules found in straight grade motor oil. Straight grade motor oil is
made from premium crude, which is expensive and sometimes in short supply.
For the reason just stated, oil companies love multi-grades because they can
be made from junk and they are a value added product.
Automakers began to use multi-grade motor oils because of ever-tightening
emission standards. The automotive engineers determined that the thin
multi-grade motor oils sealed the rings better during cold starts and
therefore caused fewer emissions. For those of you that are familiar, the
entire focus these days on emissions, are concerned with the first five
minutes of cold start, because that is about the only area of radical
improvement that can be made. That is why preheated oxygen sensors were
developed and why they are trying to develop preheated catalysts for the
exhaust. Well, the EPA, in their infinite wisdom, told the manufactures if
they wanted to use multi-grade motor oils to pass the emission testing, that
they would have to recommend the usage of multi-grades all the time. Hence
the beginning of the oil recommendations we see today. As you may have
noticed, over time the recommendations have gone from 20-50 to 10-40 to
5-30. The trend is due to the ever-tightening EPA requirements. When the
automakers need to make cleaner tail pipe emissions, for the next belt
tightening, they just recommend thinner oil. About this time you should be
feeling like a fool!!
I experimented with this while attempting to pass European Gray market cars
through the EPA labs, and found this to be true. Pipe up out there if you
are an automotive engineer of a petrochemical engineer of automotive
products.
I bought a 1988 Sea Ray in 1988. The boat had a 260 HP Chevrolet 350 cid
motor. I did not trust the boat dealership and wanted to service my boat
myself. I owned a repair shop and was completely capable and competent. I
also wanted to maintain my warranty with the boat dealer, just in case.
After performing my first oil change, I stopped at the dealer and informed
them of my oil change and provided them with the receipt from their parts
department for the filter. They said that there is no oil on this receipt.
What kind of oil did you use? I told them Delo 400 30W by Chevron. They
said good, you didn't use a multi-grade motor oil. If you had used a multi
grade, we would have to cancel your engine warranty. You see, there are no
emission requirements on boats!
You mentioned the word "cling" in your description of synthetics. The most
"clingy" oils are the ones with a high paraffin content (wax), which
historically are the Pennsylvania crudes. As evidence, have you ever
noticed on the old Pennzoil commercials, how they always use a farmer to
talk about how well the oil works in his tractor? Well, there is a damn
good reason for that! Tractors are not operated everyday. They sometimes
sit for long periods of time without usage. Then when they are started,
there can have an exaggerated amount of crank bearing wear due to the oil
running off during storage. Pennzoil would leave a waxy residue that would
help lubricate the bearings until the oil flow began. Their best spokesman
would have to be a person who is cheap, and leaves their engines idle for
long periods, like a farmer!
Although this above characterization also sounds like a classic car buff or
a Pantera owner, I would not recommend high paraffin crudes. They suffer
from the same problem as multi-grades, they break down faster and leave more
deposits (waxy looking deposits).
Synthetics were developed for jet aircraft turbine engines. In the early
days of turbine engines, the motor oil would break down and leave deposits
and cause engine damage, which would crash the plane. Synthetics allowed
higher operating temperatures with almost no breakdown (visualize the
synthetic oil commercial where they fry conventional oil in a pan and then
scrape the deposits with a spatula). However, in jet engines, the oil does
not seal the combustion chamber like in a car engine. In the early
marketing days of synthetic motor oil marketing, the salesman said you could
leave the oil in the car for 50,000 miles, just change the filter once or
twice in this period and it will be fine. They used to sell special filter
brackets that held two filters and it was bolted to a fender or something.
Well, the engineers and salesman were only considering the breakdown aspect
of the oil, not the accumulation of combustion acids. Synthetics are the
best, but must be changed as frequently at regular motor oil to prevent
combustion acid damage.
There are some cars that are so hot that they have to run synthetics or
engine deposits will form and cause engine damage even at 3000 mile oil
change intervals. The new aluminum engine corvettes are a good example of
this trend. High output motors that generate a lot of heat or that are
operated in high RPM conditions like boats, Panteras, turbine engines, etc.
Slow warm up periods also add a lot of combustion acids to the oil and can
be more harmful than driving cold. Driving forces the engine to warm up
faster and changes the combustion chamber temperature and chemistry. So my
recommendation on oil, Delo 400 30W by Chevron or Synthetic oil changed
frequently. Warm up a little, but not a lot. Start the car and use it
rather than allowing long periods of inactivity.
With a bottomless budget, use straight 30W or a heavy synthetic like 20-50W,
use an oil preheater and an electric oil pump to circulate low pressure oil
in the engine before cranking (like a turbine engine). Change the oil
before it discolors or every 3000 miles (or 3 months if it sits a lot). Use
multi grades in cold climates where 20 degree F or below start-ups are
expected. Cold climate is about the only really good use for multi-grades.
Synthetic multi-grades do not suffer from the same problems as natural crude
multi-grades. They are made multi-grade because of the manufacturer
requirements, which are EPA requirements. OMG, Spark plugs I will let
someone else explain.
Richard Schulze, P. E.
