Page 1 of 1

1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Fri Jun 17, 2016 4:43 pm
by roguewave
[Do you use Mercury oil?]

Or can you use any quality two-stroke oil?

Also, I kept hearing a beep noise when ever I pin the throttle, is that a low oil warning ?

Re:1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Fri Jun 17, 2016 8:52 pm
by jimh
Older outboard engines can generally use any TCW-3-rate oil.

To understand the meaning of the aural alert you should read the engine's owner's manual.

Re: 1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Sat Jun 18, 2016 3:26 am
by roguewave
Wish I had one to read.

Re: Obtaining Outboard Engine Manuals On-line

Posted: Sat Jun 18, 2016 10:03 am
by jimh
You can find resources for obtaining a copy of the owner's manual or operating manual for most outboard engines from the links I have collected at

http://continuouswave.com/whaler/refere ... nuals.html

Re: 1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Sat Jun 18, 2016 1:07 pm
by roguewave
Thank you very much for the link, unfortunately I'm on a boat in Maine and my iPad did not let me download it. [The "link" is just a fully-qualified hyperlink and can be accessed anywhere by any web browser; locations in Maine and Apple iOS devices are not particularly disqualified--jimh.]

I think I may have [damage] the engine by running it [while] low on two stroke oil. I'll do a compression test and see. My fault, no one to blame.

I changed out the 25-micron fuel-water separator fuel filter with a 10 micron. Could that possibly cause less fuel flow and loss of power?

I've been messing with boats and cars all my life. It was a truly a dumb move on my part to allow the oil to get low.

Re: 1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Sat Jun 18, 2016 2:18 pm
by kwik_wurk
Getting low and actually running out are two different things. Functionally when the low [oil reservoir level] alarm level goes of you get a BEEP BEEP BEEP audible alarm. Once this starts you have an 30 to 60 minutes of run time at intermediate and low speeds. When [the oil reservoir level] hits the lowest level there is still a little run time left; five minutes at the most, and the audible alarm is continuous BEEEEEEEP--if I remember correctly. Functionally I can't imagine running for long in either situation as the audible alarm is rather loud and a horrible pitch. If you ran out because [you] disabled the [alarm], well uh...

When you punch the motor the beepings sounds because the oil is shifts further aft and hence dropping in the front of the tank where the sensor is. Trim the motor up a bit and the beeps go away. If you are just at the point starting to get beeps, you should have plenty of oil'take the cowling off and see for yourself. Unless your sensor is bad.

Another audible alarm is the overheat; this is a continuous BEEEEEP and really will stay on once you ramp-up RPM. This is a concern; check water cooling and remove cowling checking for an excessively warm power head.

Any two-stroke oil will do; some burn better than others.

Re: 1998 Mercury 90-HP Two-stroke-cycle Oil; Diagnosis of Meaning of Aural Alert

Posted: Sat Jun 18, 2016 8:57 pm
by roguewave
Thank you so much for the info!