hi i have a 90 mariner optimax the oil sensor alarm on smart-craft stays on, my dealer tell me not to worry as the computer is telling them that there is a oil bottle resivour in the boat,but it is in the motor.
please help ruffy
aaaah the mighty 90 optimax, a superb engine! (i have one myself.)
lights means trouble or lack of oil. email the manufacturer if your dealer is unhelpful.
mercury/ mariner group is big.
Ruffy -- mate
Did U buy it??? 
1) rule of thumb If it is a 2 - stroke it sucks oil in no in-motor reservoir.
If it is a 4-stroke it will have an oil circulation system with an oil bath in or near the bottom of the motor (gravity controls this one).
2) I Googled "what is a 90 mariner optimax?"
The first response = "http://www.cunninghamsmarine.com.au/mariner_optimax_90.shtml"
This says yes this motor has an oil reservoir + it has a dipstick - so look for this - clue take the cover off.[}:)]
Never rely on warning lights for oil issues it is often too late. Regularly check.
AP
