At the risk of getting my a$$ flamed from all of the Amsoil devotees out
there, here is my $.02 worth. I used to use Amsoil and liked it very much. I
think it's a good product (and my father-in-law was a distributor). I also
think it's way over priced and over-sold to the consumer. It won't work
magic and it won't make an old engine new or make an old engine last longer.
Once the wear is done, it's done, period. That being said, here's my advice.
I would use either a synthetic blend or a straight synthetic such as Mobil
1. If you have a Wal-Mart near by, a complete oil change with Mobil 1 will
cost you $30.00 total, including a filter. You can't beat that with a stick.
The advantage of using the Mobil 1 at this point in your car is that it
doesn't thicken much in cold weather making starts very easy on the starter
and electrical system. The advantage there is pretty obvious given the age
of the components in your car. Second, in warm weather, Mobil 1 resists
burning and thinning better than dino juice. Amsoil will do all of this too
but Mobil 1 will do it cheaper and every bit as well. I doubt that your
engine will last longer than it would if you just changed oil regularly
using 10-40 but synthetic does tend to clean better and resist carbon build
up. All of that being said, there is no advantage to using synthetic if your
car uses oil. In fact, synthetic may cause it to use slightly more oil due
to its greater detergent factor and its better low temp flow
characteristics. So, the choice is yours. If you go with synthetics
however, keep this in mind; I would not use 20-50 when using synthetics. It
simply isn't necessary and really goes against the idea that you want lots
of flow at low temperatures. 10-40 will be more than enough. As to the large
oil ports, well, lets just say that while the mechanic means well and is
telling the truth, the ports really are nothing special. The 5.0 engine uses
larger ports so that it can move larger volumes of oil more quickly. This
engine has a number of applications that include some heavy duty towing and
hot rod use. So, large ports are dejure. But, it should be taken with a
grain of salt that these are special or require special treatment. All
larger displacement engines use larger ports than smaller displacement
engines. The fact that they're larger does not mean you should stuff heavier
weight oil through them. 10-40 or 10-30 synthetic oil will be just fine and
you may in fact, see an increase in fuel mileage on the order of 2-3%.
R. J. Talley
Teacher/James Madison Fellow
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