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The following PACKARDTIPS appeared in the Feb. /07 Traveler. I wrote it as many members have asked about the best type of oil to use in their Packards and other collectable cars. It has general application to all older cars so I felt it might be appropriate for the website, which has a wider audience. I hope the information is helpful. PACKARDTIPS
#101 WHAT
KIND OF OIL TO USE I haven’t
written a PACKARDTIPS for awhile but there have been a few topics raised over
the last year or so that are probably worth talking about. The topic of
what type of oil to use comes up most often. For the past several years I have
advised anyone who has asked me to use a Diesel rated engine oil. These can be
bought at any autoparts store. The most commonly seen is 15-40, which is perfect
for older engines. Some stores carry 15-30. This would be a better choice for a
newly rebuilt engine. The obvious
question is why? There are several reasons. The diesel rated oils contain more
dispersants and detergents. In other words they clean the engine quite well.
This is important in the case of the older cars because prior to the PCV valve,
the engines really didn’t breathe that well except a highway speeds. As a
result there was always a buildup of sludge and condensation. This brings up the next point. The diesel rated oils have additives that combat condensation. This is necessary because many diesel engines are used in marine applications where there is extreme dampness and they sit unused for long periods of time. Ever noticed how many pleasure boats never leave the dock? Diesel engines also power many stand- by generating plants where they can sit for months or even years and then suddenly have to perform at peak capacity. Vintage cars
tend to sit for months through the winter, so there is a direct connection. Lastly, the
older oils had a rating of SL, which referred to the zinc-phosphate compound
that was in them. This compound was there to protect the sliding surfaces, such
as between the camshaft and lifters from wear. The modern oils are designated SM
and do not contain this additive. It is no longer needed as almost all modern
engines are overhead cam with roller cams, so there are no sliding surfaces. The
diesel rated oils contain the SL rating and have the necessary additives. I will give
you the following example from my personal experience that will demonstrate how
well this oil performs. About four years ago I purchased a 69 AMC Ambassador SST
with a 390 engine. It is an original car with just over 100M miles. When I
bought it, it smoked at startup because the valve stem seals were rotted out.
This resulted in excess oil being sucked into the combustion chambers resulting
in excessive carbon buildup. This would contribute to sticking rings. At that
time the car went about 300 miles to the quart of oil, which was regular
automotive 10-40. I changed the valve seals and the oil mileage jumped to about
700 miles per quart. Then I heard about diesel rated 15-40 and its benefits. I
switched to that and on the first oil change the car went 1200 miles per quart.
Rather than add oil, I changed it (the oil came out as black goo) and on this
second oil change the car went 3200 miles per quart, which it still does today. I then
changed to 15-40 for my 53 Packard and 15-30 for my 37 V12 as it is a rebuilt
engine. The 53’s oil consumption improved from about 700 miles per quart to
about 1200. There was no significant difference with the 37 as it was a
“new” engine. Because it has a roller cam, it does not really need this oil,
but I believe it is better because of the other benefits previously mentioned.
For the record, the 37 does about 2000 miles per quart. The bottom line – use Diesel rated oil for your vintage, or older regular car. The benefits are significant. See Follow-up Questions and Answers |