<VV> Zinc and Oil
Eric S. Eberhard
flash at vicsmba.com
Thu Oct 8 18:11:59 EDT 2009
Opinions on oil vary so much, and the more you read the more confused
you get. Here is a good technical article on the problem with cams
and flat tappets and
These are my opinions:
I would make sure my oil was designed for flat tappet engines. For
break in and everyday use. Many companies (go to their Web Site)
have at least one oil for "racing/flat tappet engines" Some people
believe in additives, some say they don't mix well and hence do not
work. And too much zinc is worse than not enough. So I prefer to
buy mine ready to go. These come in synthetic and dinosaur.
I use Mobil 1 15-50 in almost everything -- diesel tractors, 1957 2
cyl John Deere gas tractors, Powerstroke diesel, Land Cruiser 3B
diesel, and a bunch of others. I have had great luck, but this is
only anecdotal. We live in central AZ which has "odd"
weather. First of all, 50 degree swings between night and day are
the norm. Second, the summer highs are 105 and the winter lows
14. In other words, extremes.
We have a 1980 4x4 Toyota we bought new. 245K miles, finally I see a
small puff of smoke when I start it, never have to add oil between
changes. It has always (except the 1st) had Mobil 1 although 15-50
came out later.
We have a 1992 Ford 460 big block and 1999 Powerstroke Ford diesel
with well over 120k -- no work ever, no loss of oil, no smoke in the
gasser (the diesel, depending on how I set my chip, can burn
black! but it is not oil). Both, except for the dealer's oil, only
had 15-50 Mobil 1.
I rebuilt two Corvair engines, one at a Corvair specialty shop that
breaks in the engine the "traditional way" using 30 weight Castrol or
whatever. The other was a mechanic that does a lot of Corvairs. He
also did things the traditional way. Both engines got flat cams in
under 20k miles. I rebuilt two others -- one myself and one by a
shop that does a lot of old cars. Both have only had Mobil 1 15-50
in them -- 20k, no cam problems (or other problems). I broke them in
with initial firing, and break in, and normal use, all with the same
oil. Mobil 1 15-50 is listed as "for racing/flat tappet engines" --
it has a large amount of zinc and related, just like the oils of
yore. They have 3-4 other oils with fairly high zinc, but not as
high. Mobil says their synthetic is fine to break in an engine,
Amsoil says no ... so check that as well as the zinc and preferably
specific reference to flat-tappet engines.
Again -- this is proof of nothing except that I have had very good
luck with this oil. I read the link post earlier here about oils and
that author is not hot on 15-50. Having said that, he was careful to
mention that oil should be chosen based on the operating temps ...
and few people have the extremes I have here in AZ.
If I were you I would break it in with Mobil 1 15-50 and run it on
that forever. Or find another oil you like that is specifically
recommended by the oil company for flat tappet engines. Skip the
additives (I have a few bottles if anyone wants to buy them :-) ). I
prefer synthetic because generally you can go longer between changes
which saves time, money (less oil to buy, fewer filters to buy) --
Mobil 1 recommends 15k miles between changes (I change at 5k no
matter what). It does not leak on Corvairs any more than any other
oil. In fact I have 3 Corvairs now that do not leak a drop (of
engine oil, the PG is another matter). I would also make sure the
builder really prepares the cam correctly (grease, etc, lots of
little rules and tricks on this).
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Eric S. Eberhard
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