Hello All,
I have 2001 4.3 Liter Mrecruiser I/O. I know all the Merc manuals all
say use only the Merc brand oil, but I want to know if using Mobil 1
synthetic will be better for the engine (since it is in a Blazer or S-10!!)
I know Merc wants to sell oil, but are there any cons to using synthetic
instead of the Merc dinosaur juice? Thank you in advance.

Jerry

JP wrote:
Hello All,
I have 2001 4.3 Liter Mrecruiser I/O. I know all the Merc manuals all
say use only the Merc brand oil, but I want to know if using Mobil 1
synthetic will be better for the engine (since it is in a Blazer or S-10!!)
I know Merc wants to sell oil, but are there any cons to using synthetic
instead of the Merc dinosaur juice? Thank you in advance.

Jerry



It won't be worse or detrimental. It will cost more... but not much in
the big scheme of boat ownership.

It could provide better protection in severe service or extended storage.

5W-30 would be adequate, 15W-40 too. I've used both in our antique inboard.

Rob

JP wrote:

I have 2001 4.3 Liter Mrecruiser I/O. I know all the Merc manuals all
say use only the Merc brand oil, but I want to know if using Mobil 1
synthetic will be better for the engine.

Received the following e-mail from a fellow at Mercruiser. He was
relaying information he received from their oil specialists in Fond du
Lac.

There has been quite a discussion about whether Quicksilver oil is
multi-viscosity or not. The following speaks for itself:

Quicksilver 4-Cycle marine engine lubricant is a specially blended oil
which is intended for use in our MerCruiser products. This is not an off
the shelf automotive tvpe lubricant but is specially formulated to
incorporate the features needed to satisfy the unique operating
environment of marine products.

Quicksilver oil is classified as a 25W40 multiviscosity lubricant. The
multiviscosity properties are obtained by blending very special base
stocks eliminating the need for the synthetic polymers commonly used to
give automotive lubricants their multiviscosity properties. Quicksilver
oil is a Newtonian fluid which means that the viscosity does not change
with the rate of flow. Automotive oils using a synthetic polymer to make
a 10 weight base oil have the added viscometric properties of a 30 or 40
weight oil are called non-Newtonian fluids. The viscosity does tend to
change with flow rate due to the "shearing" or breaking apart of the
long "strands" of the polymer. There are some polymers which experience
permanent shear loss resulting in a subsequent change in viscosity.

Mercruiser products are designed to operate at very high speeds and
loads when compared to a passenger car. These extreme operating
conditions can shear the polymers used in some automotive oils. The
result is a dramatic loss in oil pressure and potential engine damage.

To eliminate this problem and still provide a lubricant capable of being
used throughout a range of operating temperatures and conditions.
Quicksilver 25W40 is formulated without any polymers. The requirements
of a marine lubricant extend beyond the need to penform well at high
speeds and loads. Extended periods of idle or trolling create the need
for the oil to continue to function even when diluted with fuel and
moisture. Quicksilver 25W40 has a unique "marine" additive package to
deal with the potential problems caused by these operating conditions.
Some of the polymers used in multiviscosity oils are hygroscopic (water
gathering) and form a light brown emulsion usually observed in the
crankcase breather areas. The marine environment, being very "wet" tends
to accentuate this problem. Emulsified polymer is no longer available to
help the 10 weight base oil maintain 30 or 40 weight properties.

--
Skipper

Thanks for the info, Guys.

Jerry


"JP" wrote in message news:k%g3f.4864$bt2.2544@okepread05...
Hello All,
I have 2001 4.3 Liter Mrecruiser I/O. I know all the Merc manuals all
say use only the Merc brand oil, but I want to know if using Mobil 1
synthetic will be better for the engine (since it is in a Blazer or
S-10!!)
I know Merc wants to sell oil, but are there any cons to using synthetic
instead of the Merc dinosaur juice? Thank you in advance.

Jerry