JG Writes

I have been told that automotive synthetic oils (Mobil 1) should not be
used in a marine engine. I didn't hear the reasoning behind this statement.
Does anyone know why they should not be used?

It has been argued that in high powered motorcycles with wet clutches
Mobil 1 would cause clutch slip. Do marine engines have wet clutches?

But have I used Mobil 1 and other fully and semi-synthetic motor oils in
several big bikes without a problem. The bikes 'seemed' to rev more
freely, but the most noticeable difference was with the gear changes
which were smoother and quieter.

Several years ago on a boring late shift at work, some friends and I did
our own little oil test. We centre-drilled a number of 6mm studs and
silver soldered 8mm ball bearings to each one. We then rotated them in a
milling machine onto a mild steel plate, using a weight on the quill to
ensure equal pressure. We used a range of oils from 10W/30 through gear
oil up to Mobil 1 and Rocal machining lubricant. Times to seizure ranged
from 10 seconds for the 10W/30 to 120 seconds for the Mobile 1. The
cutting lube kept going for ever.

What was interesting was when we used Mobil 1 for a few seconds, and
then wiped it dry, the ball still took over a minute to seize on the
residue.
I finally settled on a semi-synthetic for the bikes because it seemed to
work as well as the Mobile 1, but was half the cost.

--
Trevor Dennis
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